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Homelessness or houselessness - also known as a state of being unhoused or unsheltered - is the condition of lacking stable, safe, and functional housing. The general category includes disparate situations, including:

living on the streets, also known as sleeping rough (primary homelessness)

moving between temporary shelters, including houses of friends, family, and emergency accommodation (secondary homelessness)

living in boarding houses without a private bathroom or security of tenure (tertiary homelessness)

not having access to permanent or secure housing[vague ]

internally displaced persons, who leave their domiciles because of civil conflict and are refugees within their country's borders

The legal status of homeless people varies from place to place. United States government homeless enumeration studies also include people who sleep in a public or private place, which is not designed for use as a regular sleeping accommodation for human beings. Homelessness and poverty are interrelated. There is no methodological consensus on counting homeless people and identifying their needs; therefore, in most cities, only estimated homeless populations are known.

In 2005, an estimated 100 million people worldwide were homeless, and as many as one billion people (one in 6.5 at the time) live as squatters, refugees, or in temporary shelters.

In 2009, at the United Nations Economic Commission for Europe Conference of European Statisticians (CES), the Group of Experts on Population and Housing Censuses defined homelessness as:

In its Recommendations for the Censuses of Population and Housing, the CES identifies homeless people under two broad groups:

1. Primary homelessness (or rooflessness). This category includes persons living in the streets without a shelter that would fall within the scope of living quarters

2. Secondary homelessness. This category may include persons with no place of usual residence who move frequently between various types of accommodations (including dwellings, shelters, and institutions for the homeless or other living quarters). This category includes persons living in private dwellings but reporting 'no usual address on their census form.
The CES acknowledges that the above approach does not provide a full definition of the 'homeless'.

Article 25 of the Universal Declaration of Human Rights, adopted 10 December 1948 by the UN General Assembly, contains this text regarding housing and quality of living:

Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food, clothing, housing, and medical care and necessary social services, and the right to security in the event of unemployment, sickness, disability, widowhood, old age or other lack of livelihood in circumstances beyond his control.

The ETHOS Typology of Homelessness and Housing Exclusion was developed as a means of improving the understanding and measurement of homelessness in Europe, and to provide a common "language" for transnational exchanges on homelessness. The ETHOS approach says homelessness is a process (rather than a static phenomenon) that affects many vulnerable households at different points in their lives.

The typology was launched in 2005 and is used for different purposes: as a framework for debate, for data collection purposes, policy purposes, monitoring purposes, and in the media. This typology is an open exercise that makes abstraction of existing legal definitions in the EU member states. It exists in 25 language versions, the translations being provided mainly by volunteer translators.

Recent homeless enumeration survey documentation utilizes the term unsheltered homeless. The common colloquial term "street people" does not fully encompass all unsheltered people, in that many such persons do not spend their time in urban street environments. Many shun such locales, because homeless people in urban environments may face the risk of being robbed or assaulted. Some people convert unoccupied or abandoned buildings (" squatting"), or inhabit mountainous areas or, more often, lowland meadows, creek banks, and beaches.

The Bowery Mission in New York City, c. 1800s

A homeless man living in a sewer, Vienna, Austria, c. 1900

Following the Peasants' Revolt, English constables were authorized under 1383 English Poor Laws to collar vagabonds and force them to show support; if they could not, the penalty was gaol. Vagabonds could be sentenced to the stocks for three days and nights; in 1530, whipping was added. The presumption was that vagabonds were unlicensed beggars. In 1547, a bill was passed that subjected vagrants to more provisions of the criminal law, namely two years servitude and branding with a "V" as the penalty for the first offense and death for the second. Many vagabonds were among the convicts transported to the American colonies in the 18th century.

During the 16th century in England, the state first tried to give housing to vagrants instead of punishing them, by introducing bridewells to take vagrants and train them for a profession. In the 17th and 18th centuries, these were replaced by workhouses but these were intended to discourage too much reliance on state help.

In the Antebellum South, the availability of slave labor made it difficult for poor white people to find work. To prevent them from cooperating with enslaved black people, slaveowners policed poor whites with vagrancy laws.

After the American Civil War, a large number (by the hundreds or thousands) of homeless men formed part of a counterculture known as "hobohemia" all over the United States. In smaller towns, hobos temporarily lived near train tracks and hopped onto trains to various destinations.

The growing movement toward social concern sparked the development of rescue missions, such as the U.S. first rescue mission, the New York City Rescue Mission, founded in 1872 by Jerry and Maria McAuley.

Food line at the Yonge Street Mission, Yonge Street, Toronto, Canada, in the 1930s

The U.S. Great Depression of the 1930s caused an epidemic of poverty, hunger, and homelessness in the United States. When Franklin D. Roosevelt took over the presidency from Herbert Hoover in 1933, he signed the New Deal, which expanded social welfare, including providing funds to build public housing.

How the Other Half Lives and Jack London's The People of the Abyss (1903) discussed homelessness and raised public awareness, which caused some changes in building codes and some social conditions. In England, dormitory housing called "spikes" was provided by local boroughs. By the 1930s in England, 30,000 people were living in these facilities. In 1933, George Orwell wrote about poverty in London and Paris, in his book Down and Out in Paris and London. In general, in most countries, many towns and cities had an area that contained the poor, transients, and afflicted, such as a " skid row". In New York City, for example, there was "the Bowery" - traditionally, where people with an alcohol use disorder were to be found sleeping on the streets, bottle in hand.

In the 1960s in the U.K., the nature and growing problem of homelessness changed in England as public concern grew. The number of people living "rough" in the streets had increased dramatically. However, beginning with the Conservative administration's Rough Sleeper Initiative, the number of people sleeping rough in London fell dramatically. This initiative was supported further by the incoming Labour administration from 2009 onwards with the publication of the 'Coming in from the Cold' strategy published by the Rough Sleepers Unit, which proposed and delivered a massive increase in the number of hostel bed spaces in the capital and an increase in funding for street outreach teams, who work with rough sleepers to enable them to access services.

Scotland saw a slightly different picture, with the impact of the right to buy ending in a significant drop in available social housing. The 1980s and the 1990s resulted in an ever-increasing picture of people becoming homeless.

In 2001, the Scottish Parliament came into place. It was agreed by all parties that a ten-year plan to eradicate homelessness by the end of 2012 would be implemented. The Minister of Housing met with the third sector and Local Authorities every six weeks, checking on progress, whilst consultations brought about legislative change, alongside work to prevent homelessness. There was a peak in applications around 2005, but from there onwards figures dropped year on year for the next eight years. However, with a focus on the broader numbers of people experiencing homelessness, many people with higher levels of need got caught in the system. Work from 2017 started to address this, with a framework put in place to work towards a day where everyone in Scotland has a home suitable to meet their needs.

In the U.S., the government asked many major cities to come up with a ten-year plan to end homelessness. One of the results of this was a " Housing First" solution. The Housing First program offers homeless people access to housing without having to undergo tests for sobriety and drug usage. The Housing First program seems to benefit homeless people in every aspect except for substance abuse, for which the program offers little accountability.

An emerging consensus is that the Housing First program still gives clients a higher chance at retaining their housing once they get it. A few critical voices argue that it misuses resources and does more harm than good; they suggest that it encourages rent-seeking and that there is not yet enough evidence-based research on the effects of this program on the homeless population. Some formerly homeless people, who were finally able to obtain housing and other assets which helped to return to a normal lifestyle, have donated money and volunteer services to the organizations that provided aid to them during their homelessness. Alternatively, some social service entities that help homeless people now employ formerly homeless individuals to assist in the care process.

Homeless children in the United States.[34] The number of homeless children reached record highs in 2011,[35] 2012,[36] and 2013[37] at about three times their number in 1983.[36]

Homelessness has migrated toward rural and suburban areas. The number of homeless people has not changed dramatically but the number of homeless families has increased according to a report by HUD. The United States Congress appropriated $25million in the McKinney-Vento Homeless Assistance Grants for 2008 to show the effectiveness of Rapid Re-housing programs in reducing family homelessness.

In February 2009, President Obama signed the American Recovery and Reinvestment Act of 2009, part of which addressed homelessness prevention, allocating $1.5billion for a Homeless Prevention Fund. The Emergency Shelter Grant (ESG) program's name was changed to Emergency Solution Grant (ESG) program, and funds were reallocated to assist with homeless prevention and rapid re-housing for families and individuals.

Gentrification is a process in which a formerly affordable neighborhood becomes popular with wealthier people, raising housing prices and pushing poorer residents out. Gentrification can cause or influence evictions, foreclosures, and rent regulation.

Increased wealth disparity and income inequality cause distortions in the housing market that push rent burdens higher, making housing unaffordable.

In many countries, people lose their homes by government orders to make way for newer upscale high-rise buildings, roadways, and other governmental needs. The compensation may be minimal, in which case the former occupants cannot find appropriate new housing and become homeless.

Mortgage foreclosures where mortgage holders see the best solution to a loan default is to take and sell the house to pay off the debt can leave people homeless. Foreclosures on landlords often lead to the eviction of their tenants. "The Sarasota, Florida, Herald Tribune noted that, by some estimates, more than 311,000 tenants nationwide have been evicted from homes this year after lenders took over the properties."

Rent regulation also has a small effect on shelter and street populations. This is largely due to rent control reducing the quality and quantity of housing. For example, a 2019 study found that San Francisco's rent control laws reduced tenant displacement from rent-controlled units in the short-term, but resulted in landlords removing thirty percent of the rent-controlled units from the rental market, (by conversion to condos or TICs) which led to a fifteen percent citywide decrease in total rental units, and a seven percent increase in citywide rents.

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Lack of jobs that pay living wages, lack of affordable housing, and lack of health and social services can lead to poverty and homelessness. Factors that can lead to economic struggle include neighborhood gentrification (as previously discussed), job loss, debt, loss of money or assets due to divorce, death of breadwinning spouse, being denied jobs due to discrimination, and many others.

Moreover, the absence of accessible health and social services further compounds the economic struggle for many. Inadequate healthcare can lead to untreated illnesses, making it difficult for individuals to maintain employment, perpetuating a cycle of poverty. Social services, including mental health support and addiction treatment, are essential for addressing the root causes of economic hardship. However, limited access to these services leaves vulnerable populations without the necessary support systems, hindering their ability to escape poverty.

Studies show that preventive and primary care (which homeless people are not receiving) substantially lower overall healthcare costs. In terms of providing adequate treatment to homeless people for their mental illness, the healthcare system's performance has not been promising, either.

Disabilities, especially where disability services are non-existent, inconvenient, or poorly performing can impact a person's ability to support house payments, mortgages, or rent, especially if they are unable to work. Traumatic brain injury is one main disability that can account for homelessness. According to a Canadian survey, traumatic brain injury is widespread among homeless people and, for around 70 percent of respondents, can be attributed to a time "before the onset of homelessness"

Lack of housing serves as a social determinant of mental health. Being afflicted with a mental disorder, including substance use disorders, where mental health services are unavailable or difficult to access can also drive homelessness for the same reasons as disabilities. A United States federal survey in 2005 indicated that at least one-third of homeless men and women had serious psychiatric disorders or problems. Autism spectrum disorders and schizophrenia are the top two common mental disabilities among the U.S. homeless. Personality disorders are also very prevalent, especially Cluster A.

A history of experiencing domestic violence can also attribute to homelessness. Compared to housed women, homeless women were more likely to report childhood histories of abuse, as well as more current physical abuse by male partners.

Social exclusion related to sexual orientation, gender identity or expression, or sex characteristics can also attribute to homelessness based on discrimination. Relationship breakdown, particularly with young people and their parents, such as disownment due to sexuality or gender identity is one example.

Natural disasters, including but not limited to earthquakes, hurricanes, tsunamis, tornadoes, and volcanic eruptions can cause homelessness. An example is the 1999 Athens earthquake in Greece, in which many middle class people became homeless, with some of them living in containers, especially in the Nea Ionia earthquake survivors container city provided by the government; in most cases, their only property that survived the quake was their car. Such people are known in Greece as seismopathis, meaning earthquake-struck.

War or armed conflict can create refugees fleeing the violence. Whether they be either domestic or foreign to the country, the number of migrants can outstrip the supply of affordable housing, leaving some sections of this population to be homeless.

Although uncommon, some choose to be homeless as a personal lifestyle choice.

The basic problem of homelessness is the need for personal shelter, warmth, and safety. Other difficulties include:

Homeless people in Rio de Janeiro, Brazil

Hygiene and sanitary facilities

Hostility from the public and laws against urban vagrancy

Cleaning and drying of clothes

Obtaining, preparing, and storing food

Keeping contact with friends, family, and government service providers without a permanent location or mailing address

Medical problems, including issues caused by an individual's homeless state (e.g., hypothermia or frostbite from sleeping outside in cold weather), or issues that are exacerbated by homelessness due to lack of access to treatment (e.g., mental health and the individual not having a place to store prescription drugs)

Personal security, quiet, and privacy, especially for sleeping, bathing, and other hygiene activities

Safekeeping of bedding, clothing, and possessions, which may have to be carried at all times

People experiencing homelessness face many problems beyond the lack of a safe and suitable home. They are often faced with reduced access to private and public services and vital necessities:

General rejection or discrimination from other people

Increased risk of suffering violence and abuse

Limited access to education

Loss of usual relationships with the mainstream

Not being seen as suitable for employment

Reduced access to banking services

Reduced access to communications technology

Reduced access to healthcare and dental services

Targeting by municipalities to exclude from public space

Implication of hostile architecture

Difficulty forming trust with services, systems, and other people; exacerbating pre-existing difficulty accessing aid and escaping homelessness, particularly present in the chronically homeless. Statistics from the past twenty years, in Scotland, demonstrate that the biggest cause of homelessness is varying forms of relationship breakdown.

There is sometimes corruption and theft by the employees of a shelter, as evidenced by a 2011 investigative report by FOX 25 TV in Boston, wherein several Boston public shelter employees were found stealing large amounts of from the shelter's kitchen for their private use and catering over time. Homeless people are often obliged to adopt various strategies of self-presentation to maintain a sense of dignity, which constrains their interaction with passers-by, and leads to suspicion and stigmatization by the mainstream public.

Homelessness is also a risk factor for depression caused by prejudice. When someone is prejudiced against people who are homeless and then becomes homeless themselves, their anti-homelessness prejudice turns inward, causing depression. "Mental disorders, physical disability, homelessness, and having a sexually transmitted infection are all stigmatized statuses someone can gain despite having negative stereotypes about those groups." Difficulties can compound exponentially. A study found that in the city of Hong Kong over half of the homeless people in the city (56%) had some degree of mental illness. Only 13 percent of the 56 percent were receiving treatment for their condition leaving a huge portion of homeless untreated for their mental illness.

The issue of anti-homeless architecture came to light in 2014, after a photo displayed hostile features (spikes on the floor) in London, and took social media by storm. The photo of an anti-homeless structure was a classic example of hostile architecture, in an attempt to discourage people from attempting to access or use public space in irregular ways. However, although this has only recently came to light, hostile architecture has been around for a long time in many places. An example of this is a low overpass that was put in place between New York City and Long Island. Robert Moses, an urban planner, designed it this way in an attempt to prevent public buses from being able to pass through it.

Health care for homeless people is a major public health challenge. When compared to the general population, people who are homeless experience higher rates of adverse physical and mental health outcomes. Chronic disease severity, respiratory conditions, rates of mental health illnesses, and substance use are all often greater in homeless populations than in the general population. Homelessness is also associated with a high risk of suicide attempts.

Homeless people are more likely to suffer injuries and medical problems from their lifestyle on the street, which includes poor nutrition, exposure to the severe elements of weather, and higher exposure to violence. Yet at the same time, they have reduced access to public medical services or clinics, in part because they often lack identification or registration for public healthcare services. There are significant challenges in treating homeless people who have psychiatric disorders because clinical appointments may not be kept, their continuing whereabouts are unknown, their medicines may not be taken as prescribed, medical and psychiatric histories are not accurate, and other reasons. Because many homeless people have mental illnesses, this has presented a care crisis.

The conditions affecting homeless people are somewhat specialized and have opened a new area of medicine tailored to this population. Skin conditions, including scabies, are common, because homeless people are exposed to extreme cold in the winter, and have little access to bathing facilities. They have problems caring for their feet, and have more severe dental problems than the general population. Diabetes, especially untreated, is widespread in the homeless population. Specialized medical textbooks have been written to address this for providers.

A 2011 study led by Dr. RebeccaT. Brown in Boston, conducted by the Institute for Aging Research (an affiliate of Harvard Medical School), Beth Israel Deaconess Medical Center, and the Boston Health Care for the Homeless Program found the elderly homeless population had "higher rates of geriatric syndromes, including functional decline, falls, frailty, and depression than seniors in the general population, and that many of these conditions may be easily treated if detected". The report was published in the Journal of Geriatric Internal Medicine.

There have been significant numbers of unsheltered persons dying of hypothermia, adding impetus to the trend of establishing warming centers, as well as extending enumeration surveys with vulnerability indexes.

In 1999, Dr. Susan Barrow of the Columbia University Center for Homelessness Prevention Studies reported in a study that the "age-adjusted death rates of homeless men and women were four times those of the general U.S. population and two to three times those of the general population of New York City". A report commissioned by homeless charity Crisis in 2011 found that on average, homeless people in the U.K. have a life expectancy of 47 years, 30 years younger than the rest of the population.

The homeless population often lives in higher-risk urban areas, with increased exposure and little protection from the elements. They also have limited access to clean drinking water and other methods of cooling down. The built environment in urban areas also contributes to the " heat island effect", the phenomenon whereby cities experience higher temperatures due to the predominance of dark, paved surfaces, and lack of vegetation. Homeless populations are often excluded from disaster planning efforts, further increasing their vulnerability when these events occur. Without the means to escape extreme temperatures and seek proper shelter, and cooling or warming resources, homeless people are often left to suffer the brunt of the extreme weather.

Homeless people may find it difficult to document their date of birth or their address. Because homeless people usually have no place to store possessions, they often lose their belongings, including identification and other documents, or find them destroyed by police or others. Without a photo ID, homeless persons cannot get a job or access many social services, including healthcare. They can be denied access to even the most basic assistance: clothing closets, food pantries, certain public benefits, and in some cases, emergency shelters. Obtaining replacement identification is difficult. Without an address, birth certificates cannot be mailed. Fees may be cost-prohibitive for impoverished persons. And some states will not issue birth certificates unless the person has photo identification, creating a Catch-22. This problem is far less acute in countries that provide free-at-use health care, such as the U.K., where hospitals are open-access day and night and make no charges for treatment. In the U.S., free-care clinics for homeless people and other people do exist in major cities, but often attract more demand than they can meet.

The stigmas of homelessness can thus be divided into three major categories in general:

1. Attributing homelessness to personal incompetency and health conditions (e.g., unemployment, mental health issues, substance abuse, etc.);

2. Seeing homeless people as posing threats to one's safety;

3. De-sanitizing homeless people (i.e., seeing them as pathogens). Past research has shown that those types of stigmas are being reinforced through the fact that one is homeless and have a negative impact on effective public policymaking in terms of reducing homelessness. When a person lives on a street, many aspects of their personal situations, such as mental health issues and alcoholism, are more likely to be exposed to the public as compared to people who are not homeless and have access to resources that will help improve their personal crises. Such lack of privacy inevitably reinforces stigma by increasing observations of stereotypes for the public. Furthermore, the media often attributes those personal crises to the direct cause of crimes, further leading the public to believe that homeless people are a threat to their safety. Many also believe that contacts with homeless people increase their chance of contracting diseases given that they lack access to stable, sanitary living conditions. Those types of stigmas are intertwined with each other when shaping public opinions on policies related to the homeless population, resulting in many ineffective policies that do not reduce homelessness at all. An example of such ineffective but somewhat popular policies is imposing bans on sleeping on the streets.

Relying on the famous contact hypothesis, researchers argue that increasing contact between the homeless population and non-homeless population is likely to change public opinions on this out-group and make the public more well-informed when it comes to policymaking. While some believe that the contact hypothesis is only valid on the condition that the context and type of contact are specified, in the case of reducing discrimination against the homelessness population, some survey data indicate that the context (e.g., the proportion of the homeless population in one's city) and type of contact (e.g., TV shows about the homeless population or interpersonal conversations about homelessness) do not produce many variations as they all increase positive attitudes towards homeless people and public policies that aid this group. Given that the restrictions of contexts and types of contact to reduce stigma are minimal, this finding is informative and significant to the government when it comes to making policies to offer institutional support for reducing discrimination in a country and for gauging public opinions on their proposed policies to reduce homelessness.

According to UNICEF, there are one million children living on the streets in Egypt. Other researchers estimate the number to be some three million. Homelessness NGOs assisting street children include those such as Hope Village Society, and NAFAS. Other NGOs, such as Plan International Egypt, work to reintegrate street children back into their families.

Homelessness in South Africa dates back to the apartheid period. Increasing unemployment, lack of affordable housing, social disintegration, and social and economic policies have all been identified as contributing factors to the issue. Some scholars argue that solutions to homelessness in South Africa lie more within the private sphere than in the legal and political spheres.

In 2011, there were approximately 2.41million homeless adults and 179,000 homeless children living in the country. However, one publication estimated that there were one million homeless children in China in 2012.

Housing in China is highly regulated by the Hukou system. This gives rise to a large number of migrant workers, numbering 290.77 million in 2019. These migrant workers have rural Hukou, but they move to the cities in order to find better jobs, though due to their rural Hukou they are entitled to fewer privileges than those with urban Hukou. According to Huili et al., these migrant workers "live in overcrowded and unsanitary conditions" and are always at risk of displacement to make way for new real estate developments. In 2017, the government responded to a deadly fire in a crowded building in Beijing by cracking down on dense illegal shared accommodations and evicting the residents, leaving many migrant laborers homeless. This comes in the context of larger attempts by the government to limit the population increase in Beijing, often targeting migrant laborers. However, according to official government statistics, migrant workers in China have an average of 20.4 square metres (220 square feet) of living space per capita, and the vast majority of migrant workers have basic living facilities such as heating, bathing, refrigerators, and washing machines.

Homelessness among people with mental health problems is 'much less common' in China than in high-income countries, due to stronger family ties, but is increasing due to migration within families and as a result of the one-child policy. A study in Xiangtan found at least 2439 schizophrenic people that have been homeless on a total population of 2.8million. It was found that "homelessness was more common in individuals from rural communities (where social support services are limited), among those who wander away from their communities (i.e., those not from Xiangtan municipality), and among those with limited education (who are less able to mobilize social supports). Homelessness was also associated with greater age; [the cause] may be that older patients have 'burned their bridges' with relatives and, thus, end up on the streets."

In 2020, in the wake of the COVID-19 pandemic, the Chinese Ministry of Civil Affairs announced several actions of the Central Committee in response to homelessness, including increasing support services and reuniting homeless people with their families. In Wuhan, the situation for homeless people was particularly bad, as the lockdown made it impossible for homeless migrants to return to other parts of the country. The Wuhan Civil Affairs Bureau set up 69 shelters in the city to house 4,843 people.

The Universal Declaration of Human Rights defines 'homeless' as those who do not live in a regular residence due to lack of adequate housing, safety, and availability. The United Nations Economic and Social Council Statement has a broader definition for homelessness; it defines homelessness as follows: 'When we are talking about housing, we are not just talking about four walls and a roof. The right to adequate housing is about the security of tenure, affordability, access to services, and cultural adequacy. It is about protection from forced eviction and displacement, fighting homelessness, poverty, and exclusion. India defines 'homeless' as people who do not live in census houses, but rather stay on pavements, roadsides, railway platforms, staircases, temples, streets, in pipes, or other open spaces. There are 1.77million homeless people in India, or 0.15 percent of the country's total population, according to the 2011 census consisting of single men, women, mothers, the elderly, and the disabled. However, it is argued that the numbers are far greater than accounted by the point in time method. For example, while the Census of 2011 counted 46.724 homeless individuals in Delhi, the Indo-Global Social Service Society counted them to be 88,410, and another organization called the Delhi Development Authority counted them to be 150,000. Furthermore, there is a high proportion of mentally ill and street children in the homeless population. There are 18million street children in India, the largest number of any country in the world, with 11million being urban. Finally, more than three million men and women are homeless in India's capital city of New Delhi; the same population in Canada would make up approximately30 electoral districts. A family of four members has an average of five homeless generations in India.

There is a shortage of 18.78million houses in the country. The total number of houses has increased from 52.06million to 78.48million (as per the 2011 census). However, the country still ranks as the 124th wealthiest country in the world as of 2003. More than 90million people in India make less than perday, thus setting them below the global poverty threshold. The ability of the Government of India to tackle urban homelessness and poverty may be affected in the future by both external and internal factors. The number of people living in slums in India has more than doubled in the past two decades and now exceeds the entire population of Britain, the Indian Government has announced. About 78million people in India live in slums and tenements. Seventeen percent of the world's slum dwellers reside in India. After the release of the feature film Slumdog Millionaire in 2008, Mumbai was a slum tourist destination for slumming where homeless people and slum dwellers alike could be openly viewed by tourists.

Homelessness in Indonesia refers to the issue of homelessness, a condition wherein people lack a stable and appropriate place of housing. The number of homeless people in Indonesia is estimated to be up to three million people in the country, with over 28,000 in Jakarta alone. Several terms are used to describe homeless people in Indonesia, including tunawisma, which is used by the government, and gelandangan, meaning "tramp".

Squatters and street homeless people are often targeted by police raids who say that homeless people "disturb the attractiveness of the city".

One cause of homelessness in Indonesia is forced evictions. According to researchers, between the years 2000 and 2005 over 92,000 people were forcefully evicted from their homes.

Accordin to Governor of Isfahan homeless people are an issue, per revised Article 16 of drug combat law the offenders will be forced detained for three to 6 months by either IRGC or privately outsourced. The daily cost of a person kept is 28000 toman (50 cent). At best five percent return to normal life. They may receive vocational training. Women are kept separate. Iran has a housing crisis with people who sleep in graves called Grave dwellers, buses for 25000 toman per night, rooftops or multiple families renting and sharing one single apartment. Many renters may want to rent living space in shipping containers too.

Homelessness in Israel is a phenomenon that mostly developed after the mid-1980s.

Some 2,000 families in Israel lose their homes every year after defaulting on their mortgage loans. However, a law amendment passed in 2009 protects the rights of mortgage debtors and ensures that they are not evicted after failing to meet mortgage payments. The amendment is part of a wider reform in the law in the wake of a lengthy battle by the Association for Civil Rights in Israel and other human rights groups.

In 2007, the number of homeless youth was on the rise. More than 25percent of all homeless youth in 2007 were girls, compared to 15percent in 2004. Areport by Elem, a non-profit organization that helps youth at risk, pointed to a five percent rise in the number of youths either homeless or wandering the streets late at night while their parents worked or due to strained relations at home. The organization estimated that in 2007 it provided programs or temporary shelter to roughly 32,000 youths in some 30locations countrywide.

Homelessness in Japan () is a social issue primarily affecting middle-aged and elderly males. Homelessness is thought to have peaked in the 1990s as a consequence of the collapse of the Japanese asset price bubble and has largely fallen since then.

According to the "Special Act in regards to Supporting the Autonomy of the Homeless Population" ( Japanese: ホームレスの自立の支援等に関する特別措置法)), the term "homeless" is defined as "those [people] who utilize city parks, river banks, roads, train stations, and other facilities as their place of stay to live their daily lives".

Nicknames for homeless people in Japan include hōmuresu (, from the English "homeless"), furousha ( meaning "wandering person"), kojiki ( meaning beggar), and runpen (, from German " Lumpen"). More recently, nojukusha ( "person who sleeps outside") and nojuku roudousha ( "laborer who sleeps outside") have been used to avoid negative connotations associated with the word "homeless".

There are many centers for providing food for homeless people, including the Suneboge community center.

Homelessness across the U.K. is a devolved matter, resulting in different legislation, frameworks, and even definitions, from country to country.

Since the late 1990s, housing policy has been a devolved matter, and state support for homeless people, together with legal rights in housing, have therefore diverged to a certain degree. A national service, called Streetlink, was established in 2012 to help members of the public obtain near-immediate assistance for specific rough sleepers, with the support of the Government (as housing is a devolved matter, the service currently only extends to England).

The annual number of homeless households in England peaked in 2003-04 at 135,420 before falling to a low of 40,020 in 2009-10. In 2017-18, there were 56,600 homeless households, which was 60 percent below the 2003-04 peak, and 40percent higher than the 2009-10 low. The UK has more than 120,000 children in temporary accommodation, a number which has increased from 69,050 children in 2010.

In 2007 the official figures for England were that an average of 498 people slept rough each night, with 248 of those in London.

Homelessness in England since 2010 has been rising. By 2016 it is estimated the number sleeping rough had more than doubled since 2010. The National Audit Office said about homelessness in England 2010-17 there has been a 60 percent rise in households living in temporary accommodation and a rise of 134 percent in rough sleepers. It is estimated 4,751 people bedded down outside overnight in England in 2017, up 15percent over the previous year. The housing charity Shelter used data from four sets of official 2016 statistics and calculated 254,514 people in England were homeless.

Research into Women's Homelessness in London has found that the situations people face may vary based on their background and/or experience. This is known as multiple disadvantage. The 'Making Women Count' Report Archived 13 April 2023 at the Wayback Machine, released in March 2023 found over 154 women sleeping rough in just one week. This project was made in collaboration with SHP, St Mungo's, the Women's Development Unit (Solace Women's Aid and The Connection at St Martin's London Councils and the GLA alongside researchers from PraxisCollab.

Most recently updated in October 2020, Scotland is working to eradicate homelessness through the 'Ending Homelessness Together' action plan. It is anticipated that with this, alongside a focus on prevention, and Local Authorities working with the third sector on plans known as Rapid Rehousing Transition Plans, that people will no longer be homeless for any length of time.

In terms of figures, in 2020-21, there were 42,149 people in homeless households - 30,345 adults and 11,804 children in Scotland. This was a drop of nine percent from the previous year, though it is unclear if this was partly due to statistics being collected differently during the start of the pandemic.

Graffiti of homeless in Quebec City

After Franklin D. Roosevelt took over the presidency from Herbert Hoover in 1933, he oversaw the passage of the New Deal, which greatly expanded social welfare, including providing funds to build public housing. This marked the end of the Great Depression. However, the number of homeless people grew in the 1980s, when Ronald Reagan decimated the public housing budget in the 1980s, including the federally funded affordable housing production put in place by the New Deal. By the mid-1980s, there was a dramatic increase in family homelessness. Tied into this was an increasing number of impoverished and runaway children, teenagers, and young adults, which created a new substratum of the homeless population ( street children or street youth).

In 2015, the United States reported that there were 564,708 homeless people within its borders, one of the higher reported figures worldwide.

Housing First is an initiative to help homeless people reintegrate into society, and out of homeless shelters. It was initiated by the federal government's Interagency Council on Homelessness. It asks cities to come up with a plan to end chronic homelessness. In this direction, there is the belief that if homeless people are given independent housing to start, with some proper social support, then there would be no need for emergency homeless shelters, which it considers a good outcome. However, this is a controversial position.

There is evidence that the Housing First program works more efficiently than Treatment First programs. Studies show that having the stability of housing through the Housing First program will encourage homeless people to focus on other struggles they are facing, such as substance abuse. Meanwhile, Treatment First programs promote an "all or nothing" approach which requires clients to participate in programs applicable to their struggles as a condition for housing assistance. Treatment First utilizes a less individualistic approach than Housing First and solutions are created under one standard rather than fit each client's specific needs.

Skid Row, Los Angeles contains one of the largest stable populations, between 5,000 and 8,000, of homeless people in the United States.[228]

In 2009 it was estimated that one out of 50children or 1.5 million children in the United States would experience some form of homelessness each year.

In 2010 in New York City, where there were over 36,000 homeless people in 2009, there was a mobile video exhibit in the streets showing a homeless person on a screen and asking onlookers and passersby to text with their cellphones a message for him, and they also could donate money by cellphones to the organization Pathways to Housing. In September 2010, it was reported that the Housing First Initiative had significantly reduced the chronic homeless single person population in Boston, Massachusetts, although homeless families were still increasing in number. Some shelters were reducing the number of beds due to lowered numbers of homeless, and some emergency shelter facilities were closing, especially the emergency Boston Night Center. In 2011, the Department of Veterans Affairs Supportive Services for Veterans Families Initiative, SSVF, began funding private non-profit organizations and consumer cooperatives to provide supportive services to very low-income veteran families living in or transitioning to permanent housing.

In 2019, in an interview with CBS News, scholar Sara Goldrick-Rab said that her study on college student homelessness found that "[n]early one in ten college students said they were homeless in the last year, meaning they had at least one night where they did not know where they were going to sleep."

According to the count by the Puerto Rico Department of Family, in January 2017 there were 3,501 homeless persons in the territory. The study shows that 26 percent of this population lives in the capital, San Juan. Other municipality's percentage of this population was Ponce at 6.3 percent, Arecibo at six percent, Caguas at 5.3 percent, and Mayagüez at 4.7 percent. Results from the study determined that 76 percent of the homeless population were men and 24 percent were women and that both men and women populations, were on average age, 40 years old. This steadily increasing population might have increased more drastically as a result of Hurricane María which caused over 90billion dollars in damage to the island of Puerto Rico.

Abandoned transient encampment in Mawson, ACT

Homelessness in New Zealand has been linked to the general issue of lack of suitable housing. The population of homeless people is generally measured through the country's census and by universities and other academic centres. In 2009, urban homelessness (rough sleepers or improvised dwellings) were estimated at less than 300, while rural homelessness (improvised dwellings) was estimated at between 500 and 1000. An additional 8,000-20,000 people live in "temporary accommodation unsuited for long-term habitation (caravans, campgrounds, substandard housing, and boarding houses)." Homelessness in New Zealand has traditionally been reduced by the provision of state housing, similar to Germany and other developed countries.

Statistical authorities in New Zealand have expanded their definition of homelessness to include 'people living in improvised shelters', 'people staying in camping grounds/motor camps', and 'people sharing accommodation with someone else's household'.

The issue is believed to have become increasingly visible in recent years. Media in New Zealand have published an accusatory account of the presence of homeless people in public spaces, positioning homeless men as disruptive threats. Though community members have shown support by writing opinion pieces.

In January 2019, The New York Times reported rising housing prices to be a major factor in the increasing homelessness in New Zealand so that "smaller markets like Tauranga, a coastal city on the North Island with a population of 128,000, had seen an influx of people who had left Auckland in search of more affordable housing. Average property values in Tauranga had risen to $497,000 from $304,000 in the last five years, and Demographia now rated it among the 10 least affordable cities in the world - along with famously expensive locales such as Hong Kong, San Francisco, Sydney and Vancouver, British Columbia."

In August 2019, the Associate Housing Minister Kris Faafoi and Social Development Minister Carmel Sepuloni announced that the Government would be launching a NZ$54million program to tackle homelessness in New Zealand. This includes investing $31million over the next four years for 67 intensive case managers and navigators to work with homeless people and a further $16million for the Sustaining Tenancies Programme. This funding complements the Government's Housing First programme.

After the abolition of serfdom in Russia in 1861, major cities experienced a large influx of former peasants who sought jobs as industrial workers in rapidly developing Russian industry. These people often lived in harsh conditions, sometimes renting a room shared between several families. There also was a large number of shelterless homeless people. Immediately after the October Revolution a special program of "compression" (уплотнение ) was enabled: people who had no shelter were settled in flats of those who had large (4, 5, or 6-room) flats with only one room left to previous owners. The flat was declared state property. This led to a large number of shared flats where several families lived simultaneously. Nevertheless, the problem of complete homelessness was mostly solved as anybody could apply for a room or a place in a dormitory (the number of shared flats steadily decreased after the large-scale residential building program was implemented starting in the 1960s).

By 1922 there were at least seven million homeless children in Russia as a result of nearly a decade of devastation from World War I and the Russian Civil War. This led to the creation of a large number of orphanages. By the 1930s the USSR declared the abolition of homelessness and any citizen was obliged to have a propiska - a place of permanent residency. Nobody could be stripped of propiska without substitution or refuse it without a confirmed permission (called "order") to register in another place. If someone wanted to move to another city or expand their living area, he had to find a partner who wanted to mutually exchange the flats. The right to shelter was secured in the Soviet constitution. Not having permanent residency was considered a crime.

Nevertheless, the state is still obliged to give permanent shelter for free to anybody who needs better living conditions or has no permanent registration, because the right to shelter is still included in the constitution. Several projects of special cheap 'social' flats for those who failed to repay mortgages were proposed to facilitate the mortgage market.

In western countries such as the United States, the typical homeless person is male and single, with the Netherlands reporting 80 percent of homeless people aged 18-65 to be men. Some cities have particularly high percentages of males in homeless populations, with men comprising 85 percent of the homeless in Dublin, Ireland. Non-white people are also overrepresented in homeless populations, with such groups two and one-half times more likely to be homeless in the U.S. The median age of homeless people is approximately 35.

European Union: 3,000,000 (UN-HABITAT 2004)

England: 11,580 single households were assessed as rough sleeping at the point of approach in 2021, up 39 percent from 2019-20, with 119,400 households owed a prevention duty in 2020-21 [256]

Scotland: 27,571 households were assessed as homeless in 2020 - 21, a decrease of 13 percent compared to 2019/20 [218]

Canada: 150,000[257]

Australia: On census night in 2006 there were 105,000 people homeless across Australia, an increase from the 99,900 Australians who were counted as homeless in the 2001 census[258]

Tents of homeless people in San Francisco, California, May 2020

United States:[259] The HUD 2018 Annual Homeless Assessment Report (AHAR) to Congress reports that in a single night, roughly 553,000 people were experiencing homelessness in the United States.[260] According to HUD's July 2010 fifth Homeless Assessment Report to Congress, in a single night in January 2010, the single-point analysis reported to HUD showed 649,917 people experiencing homelessness. This number had increased from January 2009's 643,067. The unsheltered count increased by 2.8 percent while the sheltered count remained the same. Also, HUD reported the number of chronically homeless people (persons with severe disabilities and long homeless histories) decreased by one percent between 2009 and 2010, from 110,917 to 109,812. Since 2007 this number had decreased by 11 percent. This was mostly due to the expansion of permanent supportive housing programs.

The change in numbers has occurred due to the prevalence of homelessness in local communities rather than other changes. According to HUD's July 2010 Homeless Assessment Report to Congress, more than 1.59 million people spent at least one night in an emergency shelter or transitional housing program during the 2010 reporting period, a 2.2 percent increase from 2009. Most users of homeless shelters used only an emergency shelter, while 17 percent used only transitional housing, and less than 5 percent used both during the reporting period. Since 2007, the annual number of those using homeless shelters in cities has decreased from 1.22 million to 1.02 million, a 17 percent decrease. The number of persons using homeless shelters in suburban and rural areas increased by 57 percent, from 367,000 to 576,000.[261] In the U.S., the federal government's HUD agency has required federally-funded organizations to use a computer tracking system for homeless people and their statistics, called HMIS (Homeless Management Information System).[262][263][264] There has been some opposition to this kind of tracking by privacy advocacy groups, such as EPIC.[265]

However, HUD considers its reporting techniques to be reasonably accurate for homeless in shelters and programs in its Annual Homeless Assessment Report to Congress.[266][267] Determining and counting the number of homeless is very difficult in general due to their lifestyle habits.[268][269] There are so-called "hidden homeless" out of sight of the normal population and perhaps staying on private property.[270] Various countries, states, and cities have come up with different means and techniques to calculate an approximate count. For example, a one-night "homeless census count", called a point-in-time (PIT) count, usually held in early winter for the year, is a technique used by several American cities, such as Boston.[271][272][273] Los Angeles uses a mixed set of techniques for counting, including the PIT street count.[270][274]

In 2003, The United States Department of Housing and Urban Development (HUD) had begun requiring a PIT count in all "Continuum of Care" communities which required them to report a count of people, housing status, and geographic locations of individuals counted. Some communities provide sub-population information to the PIT, such as information on veterans, youth, and elderly individuals, as done in Boston.[275]

Japan: 20,000-100,000 (some figures put it at 200,000-400,000).[276] Reports show that homelessness is on the rise in Japan since the mid-1990s.[277] There are more homeless men than homeless women in Japan because it is usually easier for women to get a job and they are less isolated than men. Also, Japanese families usually provide more support for women than they do for men.[278]

The number of homeless people worldwide grew steadily in 2005. In some developing countries such as Nigeria and South Africa, homelessness is rampant, with millions of children living and working on the streets. Homelessness has become a problem in the countries of China, India, Thailand, Indonesia, and the Philippines despite their growing prosperity, partly due to migrant workers who have trouble finding permanent homes.

Determining the true number of homeless people worldwide varies between 100million and one billion people based on the exact definition used. Refugees, asylum-seekers, and internally displaced persons can also be considered homeless in that they, too, experience "marginalization, minority status, socioeconomic disadvantage, poor physical health, the collapse of social supports, psychological distress, and difficulty adapting to host cultures" such as the domestic homeless.

Refugee camp in the Democratic Republic of Congo, 2013

Thus, the current definition of homelessness allows people to simplistically assume that homeless people, including refugees, are merely "without a place to live" when that is not the case. As numerous studies show, forced migration and displacement bring with it another host of problems including socioeconomic instability, "increased stress, isolation, and new responsibilities" in a completely new environment.

For people in Russia, especially the youth, alcohol, and substance use is a major cause and reason for becoming and continuing to be homeless. The United Nations Centre for Human Settlements (UN-Habitat) wrote in its Global Report on Human Settlements in 1995: "Homelessness is a problem in developed as well as in developing countries. In London, for example, life expectancy among homeless people is more than 25 years lower than the national average."

In 2008, Dr. Anna Tibaijuka, executive director of UN-HABITAT, referring to the recent report "State of the World's Cities Report 2008/2009", said that the world economic crisis we are in should be viewed as a "housing finance crisis" in which the poorest of the poor were left to fend for themselves.

There are various places where a homeless person might seek refuge:

24-hour Internet cafes are now used by over 5,000 Japanese "Net cafe refugees". An estimated 75 percent of Japan's 3,200 all-night internet cafes cater to regular overnight guests, who in some cases have become their main source of income.

24-hour McDonald's restaurants are used by "McRefugees" in Japan, China, and Hong Kong. There are about 250 McRefugees in Hong Kong.

Couch surfing: temporary sleeping arrangements in dwellings of friends or family members ("couch surfing"). This can also include housing in exchange for labor or sex. Couch surfers may be harder to recognize than street homeless people and are often omitted from housing counts.

Homeless shelters: including emergency cold-weather shelters opened by churches or community agencies, which may consist of cots in a heated warehouse, or temporary Christmas Shelters. More elaborate homeless shelters such as Pinellas Hope in Florida provide residents with a recreation tent, a dining tent, laundry facilities, outdoor tents, casitas, and shuttle services that help inhabitants get to their jobs each day.

Inexpensive boarding houses: have also been called flophouses. They offer cheap, low-quality temporary lodging.

Inexpensive motels offer cheap, low-quality temporary lodging. However, some who can afford housing live in a motel by choice. For example, David and Jean Davidson spent 22 years at various U.K. Travelodges.

Public places: Parks, bus or train stations, public libraries, airports, public transportation vehicles (by continual riding where unlimited passes are available), hospital lobbies or waiting areas, college campuses, and 24-hour businesses such as coffee shops. Many public places use security guards or police to prevent people from loitering or sleeping at these locations for a variety of reasons, including image, safety, and comfort of patrons.

Shantytowns: ad hoc dwelling sites of improvised shelters and shacks, usually near rail yards, interstates and high transportation veins. Some shantytowns have interstitial tenting areas, but the predominant feature consists of hard structures. Each pad or site tends to accumulate roofing, sheathing, plywood, and nailed two-by-fours.

Single room occupancy (more commonly abbreviated to SRO): a form of housing that is typically aimed at residents with low or minimal incomes who rent small, furnished single rooms with a bed, chair, and sometimes a small desk. SRO units are rented out as permanent residence or primary residence to individuals, within a multi-tenant building where tenants share a kitchen, toilets or bathrooms. In the 2010s, some SRO units may have a small refrigerator, microwave, and sink. (also called a "residential hotel").

Squatting in an unoccupied structure where a homeless person may live without payment and the owner's knowledge or permission. Often these buildings are long abandoned and not safe to occupy.

Tent cities: ad hoc campsites of tents and improvised shelters consisting of tarpaulins and blankets, often near industrial and institutionally zoned real estate such as rail yards, highways and high transportation veins. A few more elaborate tent cities, such as Dignity Village, are hybrids of tent cities and shantytowns. Tent cities frequently consist only of tents and fabric-improvised structures, with no semi-permanent structures at all.

Outdoors: on the ground or in a sleeping bag, tent, or improvised shelter, such as a large cardboard box, under a bridge, in an urban doorway, in a park, or in a vacant lot.

Tunnels such as abandoned subway, maintenance, or train tunnels are popular among long-term or permanent homeless people. The inhabitants of such refuges are called in some places, like New York City, "Mole People". Natural caves beneath urban centers allow for places where people can congregate. Leaking water pipes, electric wires, and steam pipes allow for some of the essentials of living.

Vehicles: cars or trucks used as temporary or sometimes long-term living quarters, for example by those recently evicted from a home. Some people live in recreational vehicles (RVs), school buses, vans, sport utility vehicles, covered pickup trucks, station wagons, sedans, or hatchbacks. The vehicular homeless, according to homeless advocates and researchers, comprise the fastest-growing segment of the homeless population. Many cities have safe parking programs in which lawful sites are permitted at churches or in other out-of-the-way locations. For example, because it is illegal to park on the street in Santa Barbara, California, the New Beginnings Counseling Center worked with the city to make designated parking lots available to homeless people.

Foyers are a specific type of transitional housing designed for homeless or at-risk teens. Foyers are generally institutions that provide affordable accommodation as well as support and training services for residents. They were pioneered in the 1990s in the United Kingdom, but have been adopted in areas in Australia and the United States as well.

Supportive housing is a combination of housing and services intended as a cost-effective way to help people live more stable, productive lives. Supportive housing works well for those who face the most complex challenges - individuals and families confronted with homelessness who also have very low incomes or serious, persistent issues such as substance use disorder, addictions, alcohol use disorder, mental illness, HIV/AIDS, or other serious challenges. A 2021 systematic review of 28 interventions, mostly in North America, showed that interventions with the highest levels of support led to improved outcomes for both housing stability, and health outcomes.

Government initiatives: In South Australia, the state government of Premier Mike Rann (2002-2011) committed substantial funding to a series of initiatives designed to combat homelessness. Advised by Social Inclusion Commissioner David Cappo and the founder of New York's Common Ground program, Rosanne Haggerty, the Rann government established Common Ground Adelaide, building high-quality inner city apartments (combined with intensive support) for "rough sleeping" homeless people. The government also funded the Street to Home program and a hospital liaison service designed to assist homeless people admitted to the emergency departments of Adelaide's major public hospitals. Rather than being released back into homelessness, patients identified as rough sleepers were found accommodation backed by professional support. Common Ground and Street to Home now operate across Australia in other States.

This section focuses only on Please help one specialized aspect of the subject. improve this article by adding general information and discuss at the talk page.

While some homeless people are known to have a community with one another, providing each other various types of support, people who are not homeless also may provide them friendship, relational care, and other forms of assistance. Such social support may occur through a formal process, such as under the auspices of a non-governmental organization, religious organization, or homeless ministry, or may be done on an individual basis.

The United States Department of Labor has sought to address one of the main causes of homelessness, a lack of meaningful and sustainable employment, through targeted training programs and increased access to employment opportunities that can help homeless people develop sustainable lifestyles. This has included the development of the United States Interagency Council on Homelessness, which addresses homelessness on the federal level in addition to connecting homeless individuals to resources at the state level. All individuals who are in need of assistance are able, in theory, to access employment and training services under the Workforce Investment Act (WIA), although this is contingent upon funding and program support by the government.

Homeless people can also use waste management services to earn money. Some homeless people find returnable bottles and cans and bring them to recycling centers to earn money. They can sort out organic trash from other trash or separate out trash made of the same material (for example, different types of plastics, and different types of metal). In addition, rather than picking waste at landfills, they can also collect litter found on/beside the road to earn an income.

A street newspaper vendor, selling Street Sheet, in San Francisco, United States

Street newspapers are newspapers or magazines sold by homeless or poor individuals and produced mainly to support these populations. Most such newspapers primarily provide coverage of homelessness and poverty-related issues and seek to strengthen social networks within homeless communities, making them a tool for allowing homeless individuals to work.

The 2010 passage of the Patient Protection and Affordable Care Act could provide new healthcare options for homeless people in the United States, particularly through the optional expansion of Medicaid. A2013 Yale study indicated that a substantial proportion of the chronically homeless population in America would be able to obtain Medicaid coverage if states expanded Medicaid under the Affordable Care Act.

In 1985, the Boston Health Care for the Homeless Program was founded to assist the growing numbers of homeless people living on the streets and in shelters in Boston who were suffering from a lack of effective medical services. In 2004, Boston Health Care for the Homeless in conjunction with the National Health Care for the Homeless Council published a medical manual called The Health Care of Homeless Persons, edited by James J. O'Connell, M.D., specifically for the treatment of the homeless population. In June 2008 in Boston, the Jean Yawkey Place, a four-story, 7,214.2-square-metre (77,653 sq ft) building, was opened by the Boston Health Care for the Homeless Program. It is an entire full-service building on the Boston Medical Center campus dedicated to providing healthcare for homeless people. It also contains a long-term care facility, the Barbara McInnis House, which expanded to 104 beds and is the first and largest medical respite program for homeless people in the United States.

In Los Angeles, a collaboration between the Ostrow School of Dentistry of the University of Southern California and the Union Rescue Mission shelter offers homeless people in the Skid Row area free dental services.

Studies on the effects of intensive mental health interventions have demonstrated some improvements in housing stability and to be economically beneficial on cost-analysis.

In 2013, a Central Florida Commission on Homelessness study indicated that the region spends $31,000 a year per homeless person to cover "salaries of law enforcement officers to arrest and transport homeless individuals - largely for nonviolent offenses such as trespassing, public intoxication or sleeping in parks - as well as the cost of jail stays, emergency room visits and hospitalization for medical and psychiatric issues. This did not include "money spent by nonprofit agencies to feed, clothe and sometimes shelter these individuals". In contrast, the report estimated the cost of permanent supportive housing at "$10,051 per person per year" and concluded that "[h]ousing even half of the region's chronically homeless population would save taxpayers $149million over the next decade - even allowing for ten percent to end up back on the streets again." This particular study followed 107 long-term-homeless residents living in Orange, Osceola, and Seminole Counties. Similar studies are showing large financial savings in Charlotte, North Carolina, and southeastern Colorado from focusing on simply housing homeless people.

In general, housing interventions had mixed economic results in cost-analysis studies.

Voting for elected officials is important for the population of homeless people to have a voice in the democratic process.

Homeless veteran man in New York United States

Many homeless organizations support homeless veterans, an issue most commonly seen in the United States.

Non-governmental organizations house or redirect homeless veterans to care facilities. Social Security Income/Social Security Disability Income, Access, Outreach, Recovery Program (SOAR) is a national project funded by the Substance Abuse and Mental Health Services Administration. It is designed to increase access to SSI/SSDI for eligible adults who are homeless or at risk of becoming homeless and have a mental illness or a co-occurring substance use disorder. Using a three-pronged approach of Strategic Planning, Training, and Technical Assistance (TA), the SOAR TA Center coordinates this effort at the state and community level.

The United States Department of Housing and Urban Development and Veterans Administration have a special Section 8 housing voucher program called VASH (Veterans Administration Supported Housing), or HUD-VASH, which gives out a certain number of Section8 subsidized housing vouchers to eligible homeless and otherwise vulnerable US armed forces veterans. The HUD-VASH program has shown success in housing many homeless veterans. The support available to homeless veterans varies internationally, however. For example, in England, where there is a national right to housing, veterans are only prioritized by local authority homelessness teams if they are found to be vulnerable due to having served in the Armed Forces.

Under the Department of Labor, the Veterans' Employment and Training Service (VETS) offers a variety of programs targeted at ending homelessness among veterans. The Homeless Veterans Reintegration Program (HVRP) is the only national program that is exclusively focused on assisting veterans as they reenter the workforce. The VETS program also has an Incarcerated Veterans' Transition Program, as well as services that are unique to female Veterans. Mainstream programs initiated by the Department of Labor have included the Workforce Investment Act, One-Stop Career Centers, and a Community Voice Mail system that helps to connect homeless individuals around the United States with local resources. Targeted labor programs have included the Homeless Veterans Reintegration Project, the Disability Program Navigator Initiative, efforts to end chronic homelessness through providing employment and housing projects, Job Corps, and the Veterans Workforce Investment Program (VWIP).

Homelessness in popular culture is depicted in various works.

Modern Times, a 1936 film, shows the negative effects of vagrancy laws.

Cathy Come Home, 1966, shows the effects of homelessness on parenthood.

God Bless the Child, 1988, a made-for-TV movie about single mother (Mare Winningham) living on the streets of New York City with her young daughter.

Homeless Sam & Sally, a 2020 dark comedy film and television series with the same name released in 2019, is story about a mother named Sally Silver and her mentally ill son Sam Silver who comes up with ways to live normal lives while being homeless in Koreatown, Los Angeles.

, 2000, a documentary by Marc Singer, who followed the lives of people living in the Freedom Tunnel, an Amtrak tunnel in New York City.

Homeless to Harvard: The Liz Murray all at Story, a 2003 film about a homeless girl, Liz Murray, who works her way up to admission to Harvard University.

66 Months, a 2011 British documentary film about a homeless man who makes it on his own for six years without any government programs helping him.

The Pursuit of Happyness, a 2006 biographical film where a father and son get a job and end up homeless after an eviction and later a tax garnishment. After several weeks living from place to place in 1981 San Francisco, he lands a permanent position in a brokerage firm after completing an unpaid internship.

Same Kind of Different as Me, a 2017 American film about a successful art dealer, his wife, and an initially violent member of a homeless shelter community. It is based on the 2006 book of the same name.

Curly Sue, a 1991 comedy-drama that focuses on a homeless con artist and his friend who gets lucky with a roof over their heads by tricking a wealthy attorney.

Life Stinks, a 1991 comedy about a wealthy businessman who bets a corporate rival that he can live his life as a homeless man, but finds out later on in the story that being homeless is not easy or fun.

The Saint of Fort Washington, a 1993 drama where a homeless disabled man gets guidance from a friendly veteran as they cope with the realities of living on the streets.

Anderberg, Kristen (2011). 21st Century Essays on Homelessness. Seaward Avenue Press. ISBN 978-1456532369.

Arumi, Ana Maria, Yarrow, Andrew L., "Compassion, Concern, and Conflicted Feelings: New Yorkers on Homelessness and Housing" Archived 18 October 2017 at the Wayback Machine, Public Agenda Foundation, February 2007

Commonwealth of Massachusetts, Department of Housing and Community Development, Homelessness Commission, Commission to End Homelessness, "Report of the Special Commission Relative to Ending Homelessness in The Commonwealth", Final Report, December 2007

Crosette, Barbara, "Homeless and Hungry Youths of India", The New York Times, 23 December 1990.

Desjarlais, Robert R., Shelter blues: sanity and selfhood among the homeless, University of Pennsylvania Press, 1997

Friedman, Donna H., et al., "Preventing Homelessness and Promoting Housing Stability: A Comparative Analysis", The Boston Foundation, June 2007.

Howard, Ella (2013). Homeless: Poverty and Place in Urban America. Philadelphia: University of Pennsylvania Press. ISBN 978-0812244724.

Institute of Medicine (U.S.), Committee on Healthcare for Homeless People, "Homelessness, Health, and Human Needs", Washington, D.C. : National Academy Press, 1988. ISBN 0309038359

Journal of Social Distress and the Homeless, Springer Verlag and Psycke-Logos Press.

Massachusetts Coalition for the Homeless, 2005-2006 edition [1984], Lynn, Massachusetts.

Katz, Jessica Ilana, "Homelessness, Crime, Mental Illness, and Substance Abuse: A Core Population with Multiple Social Service Needs", Department of Urban Planning and Studies, Massachusetts Institute of Technology, June 2003

Kenyon, Thomas, What You Can Do to Help the Homeless (Simon & Schuster, 1991)[ISBN missing ]

Min, Eungjun, (editor), Reading the Homeless: The Media's Image of Homeless Culture, Praeger Publishers, 1999. ISBN 0275959503

National Coalition for the Homeless, "American Nightmare: A Decade of Homelessness in the United States", December 1989

Nieto G., Gittelman M., Abad A. (2008). "Homeless Mentally Ill Persons: A bibliography review", International Journal of Psychosocial Rehabilitation. 12(2)

O'Flaherty, Brendan, Making room : the economics of homelessness, Cambridge, Mass. : Harvard University Press, 1996. ISBN 0674543424

Office for Public Management (UK), "Tackling Homelessness: learning from New York" Archived 10 August 2009 at the Wayback Machine, Seminar Report, London, February 2004

Scanlon, John, "Homelessness: Describing the Symptoms, Prescribing a Cure", The Heritage Foundation, Backgrounder No. 729, 2 October 1989

Miya Yoshida, "The Hidden Homeless in Japan's Contemporary Mobile Culture", NeMe, 2012

Southard, Peggy Ann Dee, "Looking for Sanctuary: Staying on Publicly Owned Lands as a Response to Homelessness", a dissertation presented to the Department of Sociology and the Graduate School of the University of Oregon.

Tsesis, Alexander, "Eliminating the Destitution of America's Homeless", Temple Political & Civil Rights Law Review, Vol. 75, No. 539, 2002, Temple University Beasley School of Law

University of Michigan Libraries, Selected Bibliography of Homelessness Resources

Wright, James D. (1989). Address Unknown: The Homeless in America (3rd ed.). New York: Transaction Publishers. ISBN 978-0202364094.

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Homelessness or houselessness - also known as a state of being unhoused or unsheltered - is the condition of lacking stable, safe, and functional housing.

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The last official tally of people living on the street was last taken in January 2020 - before COVID-19 ravaged the economy - and showed 161,548 people experiencing homelessness in California, with the biggest concentration in Los Angeles. The January 2021 count was postponed due to COVID-19, but is expected to take place again in 2022.

Those numbers should be taken with a grain of salt, as they're gathered on a single cold night in January by volunteers to provide a snapshot of homelessness. Experts say this method likely underestimates the unsheltered, and doesn't capture the total number of people who fall into homelessness over the course of a year, which could be two or three times higher.

It's not surprising that California, the largest state, has the biggest homeless population in the country. But while about 1 in 8 Americans lives in California, more than 1 in 4 homeless Americans live here. New York and Hawaii have slightly higher per capita rates of homelessness, but California has the largest proportion of people living without shelter - about 70% of homeless people here reside outdoors. That means the state's homeless population is far more visible than in other places, and more vulnerable to the illness, violence and death that accompany living on the street. California also saw the largest increase in homelessness of any state in 2020, a 6.8% jump.

Newly released state numbers show that throughout 2020, nearly a quarter of a million people accessed homeless services through local agencies. About 160,000 were single adults, and nearly 85,000 in families with kids. About 90,000 of those who accessed services were in Los Angeles County. That data - submitted by 42 of the 44 local agencies that manage homeless dollars and services across the state - was not previously compiled or made public. That number is dynamic, and about 50% higher than the one-night snapshot, because someone may have been homeless at the start of the year, but housed by the end - or vice versa.

But it, too, could be an undercount, as it excludes some individuals who never interacted with homeless providers and also doesn't include survivors of domestic violence who are omitted for safety purposes, according to Ali Sutton, the state deputy secretary for homelessness.

According to the state, nearly 40% of the quarter million who accessed homeless services, moved into permanent housing in 2020 - which could mean anything from moving back in with a family member to getting their own place.

Military veterans, at higher risk of mental illness and substance abuse issues, make up a disproportionate share of the country's homeless population. Roughly 11,000 veterans experience homelessness in California on any given night, about 8% of the state's total homeless population. Most vets experiencing homelessness are over age 50, and often have significant disabilities and medical conditions that are exacerbated by precarious housing situations. Military members who experienced an episode of sexual trauma during their service are at especially high risk.

The good news is that the number of vets living on the streets has declined significantly over the past decade, both nationally and in California. Experts credit initiatives from the Obama administration incentivizing a "housing-first" approach - where permanent housing is provided without preconditions for addiction or mental health treatment - to help homeless vets. The city of Riverside succeeded in housing all 89 of its homeless veterans after adopting that approach.

While homelessness among families is also down over the last decade, that was the fastest growing group in 2020's point in time count. About 8,000 families and 12,000 children were homeless in California last year. In Los Angeles, their number spiked by 45.7%. As a result, family homelessness was the main focus of the 2021-22 state budget; Newsom announced a goal of zero family homelessness in the next five years.

Unlike households without children, those with at least one child are far more likely to utilize emergency shelter or transitional housing. One striking statistic: Infancy is the age at which a person in the United States is most likely to be found in a homeless shelter. Several studies have found strong correlations between early childhood housing instability and behavioral and learning difficulties later in school.

Survivors of domestic violence are among those at high risk of homelessness. One California study found that women reporting an episode of domestic violence were four times more likely to suffer housing instability than other women.

The formerly incarcerated - ineligible for many public housing programs and frequently a target of discrimination in the rental housing market - often take refuge in emergency shelters or on the streets. While comprehensive California data is lacking, one study by a criminal justice reform advocacy group found that people who have been in jail or prison are ten times more likely to experience homelessness than the general public.

Youth aging out of the foster care system likely constitute a significant share of the more than 11,000 homeless young adults in California. One study found 30% of former foster care children in the Midwest were homeless at least once before age 24. Lacking family support networks and often victims of childhood traumas, about 25% of California's foster youth transitioning into adulthood live in precarious housing situations.

California has a patchwork of government-provided housing for people experiencing homelessness. While the nomenclature varies from city to city, the two most prevalent and important categories of housing are emergency shelters and permanent supportive housing.

Emergency Shelters: These are any facilities that provide temporary shelter for people experiencing homelessness. At their most basic they are a barracks-like arrangement of cots, and provide a bed and a meal. Typically they are operated by publicly funded nonprofit and religious organizations. Many shelters bar residents from staying with partners or pets, and are often viewed by homeless people as dangerous and dirty, even compared to sleeping on the streets. A KPCC investigatio n of Los Angeles area shelters last year found reports of rats, bedbugs, foul odors and harassment rampant at several shelters.

But while shelter beds frequently go unused in Los Angeles County, where transportation is also a complicating factor, overall the state has a major shortage. Cities and counties across California reported last year a little more than 53,000 beds in either an emergency shelter or transitional housing - or fewer than one bed for every three people. In some areas, the ratio is as high as five people per bed; no county has at least one full bed per person.

San Francisco and Los Angeles have tried to reinvent emergency shelters, equipping them with health and social services providers who can help guide residents to more stable housing outcomes. According to city officials more than 50% of the short-term residents of San Francisco's "navigation centers," which are tailored to high-needs clients, are ultimately placed in housing. Emergency shelters are generally much cheaper to build than permanent supportive housing, but new projects often run into stringent community opposition.

Permanent Supportive Housing: Homelessness experts agree that emergency shelters are mostly just a Band-Aid - permanent supportive housing is the long-term solution. Usually targeted at the chronically homeless, this offers a highly subsidized apartment paired with support services including psychological counseling, substance abuse rehab and job training. Permanent supportive housing is a pillar of the "housing first" model of ending homelessness: Individuals don't need to quit drugs or agree to participate in any program to get a permanent roof over their head. Studies show that once placed in permanent supportive housing, residents tend to stay off the streets and out of the hospital and jail, saving taxpayers considerable expense.

One problem: Permanent supportive housing is really expensive to build. In Los Angeles, a recent estimate from the city auditor put the median cost of building one unit at more than $530,000. A new project coming on line in San Jose is estimated to pencil out at roughly $470,000 per unit. The outrageous price tags aren't just driven by land costs - a shortage of construction labor and prolonged city approval processes are also to blame. Cities including Oakland have recently begun buying and converting single-room occupancy hotels to sidestep prohibitively high new construction costs.

California spent about $13 billion over the last three years to address homelessness, with few visible results. A scathing state auditor's report from February points to a main culprit: a lack of coordination and accountability across the complicated web of state agencies and local counties, cities and service providers.

But data from service providers across the state says more than 91,000 people moved from homelessness into permanent housing in 2020. State officials are hoping that number will be even higher in the coming years, after committing a record-breaking $12 billion in the 2021-22 budget to homelessness.

The biggest line item in the budget is Project Homekey, an initiative started during the pandemic in which local governments bought and renovated 94 hotels and motels into about 6,000 permanent housing units. Funding for that was tripled in 2021, jumping from $846 million to $2.75 billion. Another $2.2 billion over the next three years will go to create behavioral health facilities. Local jurisdictions also got $2 billion in annual funding over two years, which they will be able to spend flexibly on their specific needs.

Some U.S. cities, counties and states have made enviable progress in reducing homelessness, revealing possible solutions for California. Four communities have been recognized by the U.S. Interagency Council on Homelessness for effectively ending chronic homelessness, meaning that any homeless person with a disability is immediately provided shelter and is able to land permanent housing within 90 days if he or she wants. Three states and 78 communities have ended veteran homelessness.

Houston has reduced homelessness by more than half, from a peak of around 8,000 in 2011 to around 3,000 in 2021, according to federal point-in-time data. The city began by bringing together more than 100 agencies, including the city of Houston, the counties, nonprofit agencies, businesses and the federal HUD. Coalition members continually update a data dashboard that tracks homeless people as they interact with shelters and services. During regular meetings, they match a list of homeless people seeking permanent supportive housing with spots. A sobriety center provides a safe place for people who are publicly intoxicated to sober up - and avoid an arrest record. Federal funding has been key to bringing thousands of new supportive housing units online: HUD nearly doubled its funding for Houston homelessness programs between 2008 and 2018, to $38.2 million.

In Atlanta, a city similar in population to Sacramento or Long Beach, the homeless population has also more than halved since 2010, even as rents have raced upwards. Like Houston, Atlanta has embraced the "housing first" approach, investing public and private dollars in a growing stock of low-barrier shelter beds, rapid rehousing units and permanent supportive housing. One innovative solution: A host-family program that pairs homeless LGBTQ young adults with supportive households.

Matt Levin was the data and housing dude for CalMatters. His work entails distilling complex policy topics into easily digestible charts and graphs, finding and writing original stories from data, yelling... More by Matt Levin

Jackie covered income inequity and economic survival for the The California Divide collaboration from 2019 through 2021. She was awarded a Pulitzer Prize in Explanatory Reporting in 2021 for a Reuters... More by Jackie Botts

Manuela is our former Housing Reporter whose stories focused on the political dynamics and economic and racial inequities that contribute to the housing crisis in California and its potential solutions.... More by Manuela Tobias

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California's homelessness crisis - and possible solutions - explained

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California's most vexing issue is its most shameful: the rising number of people who lack a home. What to know about the problem and solutions.

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Climate Change: Vital Signs of the Planet

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Our Trajectory

Earth Will Continue to Warm and the Effects Will Be Profound

The potential future effects of global climate change include more frequent wildfires, longer periods of drought in some regions, and an increase in the wind intensity and rainfall from tropical cyclones. Credit: left - Mike McMillan/USFS, center - Tomas Castelazo / Wikimedia Commons / CC BY-SA 4.0, right - NASA.

Global climate change is not a future problem. Changes to Earth's climate driven by increased human emissions of heat-trapping greenhouse gases are already having widespread effects on the environment: glaciers and ice sheets are shrinking, river and lake ice is breaking up earlier, plant and animal geographic ranges are shifting, and plants and trees are blooming sooner.

Effects that scientists had long predicted would result from global climate change are now occurring, such as sea ice loss, accelerated sea level rise, and longer, more intense heat waves.

" The magnitude and rate of climate change and associated risks depend strongly on near-term mitigation and adaptation actions, and projected adverse impacts and related losses and damages escalate with every increment of global warming."

- Intergovernmental Panel on Climate Change

Some changes (such as droughts, wildfires, and extreme rainfall) are happening faster than scientists previously assessed. In fact, according to the Intergovernmental Panel on Climate Change (IPCC) - the United Nations body established to assess the science related to climate change - modern humans have never before seen the observed changes in our global climate, and some of these changes are irreversible over the next hundreds to thousands of years.

Scientists have high confidence that global temperatures will continue to rise for many decades, mainly due to greenhouse gases produced by human activities.

A Degree of Difference

So, the Earth's average temperature has increased about 2 degrees Fahrenheit during the 20th century. What's the big deal?

Read more

The IPCC's Sixth Assessment report, published in 2021, found that human emissions of heat-trapping gases have already warmed the climate by nearly 2 degrees Fahrenheit (1.1 degrees Celsius) since 1850-1900. The global average temperature is expected to reach or exceed 1.5 degrees C (about 3 degrees F) within the next few decades. These changes will affect all regions of Earth.

What's the difference between climate change and global warming?

"Global warming" refers to the long-term warming of the planet. "Climate change" encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.

detailed answer

The severity of effects caused by climate change will depend on the path of future human activities. More greenhouse gas emissions will lead to more climate extremes and widespread damaging effects across our planet. However, those future effects depend on the total amount of carbon dioxide we emit. So, if we can reduce emissions, we may avoid some of the worst effects.

" The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss the brief, rapidly closing window to secure a liveable future." ²

- Intergovernmental Panel on Climate Change

Future Effects in the U.S.

U.S. Regional Effects

U.S. Regional Effects

Climate change is bringing different types of challenges to each region of the country. Some of the current and future impacts are summarized below. These findings are from the Third and Fourth National Climate Assessment Reports, released by the U.S. Global Change Research Program.

Is it too late to prevent climate change?

Humans have caused major climate changes to happen already, and we have set in motion more changes still. However, if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries.

detailed answer

Northeast. Heat waves, heavy downpours, and sea level rise pose increasing challenges to many aspects of life in the Northeast. Infrastructure, agriculture, fisheries, and ecosystems will be increasingly compromised. Farmers can explore new crop options, but these adaptations are not cost- or risk-free. Moreover, adaptive capacity, which varies throughout the region, could be overwhelmed by a changing climate. Many states and cities are beginning to incorporate climate change into their planning.

Northwest. Changes in the timing of peak flows in rivers and streams are reducing water supplies and worsening competing demands for water. Sea level rise, erosion, flooding, risks to infrastructure, and increasing ocean acidity pose major threats. Increasing wildfire incidence and severity, heat waves, insect outbreaks, and tree diseases are causing widespread forest die-off.

Southeast. Sea level rise poses widespread and continuing threats to the region's economy and environment. Extreme heat will affect health, energy, agriculture, and more. Decreased water availability will have economic and environmental impacts.

Midwest. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. Climate change will also worsen a range of risks to the Great Lakes.

Southwest. Climate change has caused increased heat, drought, and insect outbreaks. In turn, these changes have made wildfires more numerous and severe. The warming climate has also caused a decline in water supplies, reduced agricultural yields, and triggered heat-related health impacts in cities. In coastal areas, flooding and erosion are additional concerns.

References
References
Header image shows cracked mud stretches across sections of the Panamint Valley. Credit: NPS/Kurt Moses; A degree of concern thermometer image credit: Pixabay/geralt

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intergovernmental panel on climate change

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Vital Signs of the Planet: Global Climate Change and Global Warming. Long-term effects of global climate change in the United States.

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The video of George Floyd's death at the hands of police in Minneapolis triggered protests around the world. It brought renewed attention to the high-profile deaths of black Americans during the past decade and ongoing concerns about systemic racism in the criminal justice system.

Floyd's killing, in the midst of the coronavirus pandemic, which has disproportionately infected and killed black people, has exposed long-standing racial inequities in every aspect of American life and forced a deep reckoning across society. Corporations are pledging to combat systemic racism in their companies. Some cities are considering proposals to reduce funds to police departments. And activists have renewed calls to remove Confederate monuments, with some even toppling the statues themselves.

As former vice president Joe Biden prepared to announce his running mate, Black leaders pushed for him select a Black woman. Biden named Sen. Kamala D. Harris (D-Calif.) on Aug. 11, making her the first woman of color on a major-party presidential ticket. Harris has since been working to galvanize Black communities and progressive voters.

To help provide context to the issues driving the debate among people attending marches and rallies or those having more quiet conversations with their families and friends, we've compiled deeply reported stories, videos, photo essays, audio and graphics on black history, progress, inequality and injustice.

Sign up for the About US newsletter for candid conversations about identity in 21st-century America.

When did slavery begin in America? Historians are trying to find out as much as possible about Angela, the first African woman documented in Virginia. Her arrival in Jamestown in 1619 marked the beginning of a subjugation that left millions in chains.

University of Virginia confronts its Jeffersonian roots in a memorial to enslaved laborers. Thomas Jefferson founded the university in 1819, designed the campus and laid out an ambitious academic agenda. The Memorial to Enslaved Laborers acknowledges the estimated 4,000 enslaved people who lived and worked at the university from 1817 to 1865.

What does it mean to Daniel Smith to be the living son of an enslaved person in the 21st century? Looking back, he can now see his parents as followers of the "twice as good" philosophy - the futile belief that black people must perform twice as well as whites just to be considered equal. And beneath the sunny message of how extraordinary the Smith children were lay Abram Smith's stories of slavery with their frightening symbols of brutality.

"Jim Crow" first appeared in the North. An early civil rights struggle in Massachusetts featuring a young Frederick Douglass shows the forgotten northern origins of racial separation.

Historians believe that as many as 300 black people were killed, and 40 square blocks of what was known as Black Wall Street were destroyed by fire. A century after a race massacre, Tulsa finally digs for suspected mass graves. The work comes nearly seven months after a team of forensic anthropologists and archaeologists, led by the Oklahoma Archaeological Survey at the University of Oklahoma, announced that they had found "possible common graves" at two sites in Tulsa.

The four days in 1968 that reshaped D.C.: On April 4, 1968, shortly after 8 p.m., word reached the District that the Rev. Martin Luther King Jr. had been slain in Memphis. His assassination ignited an explosion of rioting, looting and burning that stunned Washington and would leave many neighborhoods in ruins for 30 years.

Juneteenth celebrates "a moment of indescribable joy": It has its roots in the long-awaited moment of emancipation in Texas, where more than 250,000 enslaved black people received news on June 19, 1865 - more than two years after President Abraham Lincoln's Emancipation Proclamation - that they were free.

Why Americans don't learn about Tulsa, or Juneteenth: The legacy of two moments in history that many Americans are just beginning to learn.

The quest to identify black Americans' roots: From exploring sunken vessels of the Middle Passage to reconstructing museum exhibits that chronicle slavery, African Americans are breaking down the barriers that separate them from their ancestors and are reconnecting with a lineage once lost.

'Historically Black': An eight-episode audio miniseries that brings black history to life through personal heirlooms and their stories.

"The textbooks were pretty whitewashed. We never talked about the conditions of slavery or why it persisted." A range of critics - historians, educators, civil rights activists - want to change how schools teach the subject. The evidence of slavery's legacy is all around us, they say, pointing to the persistence of segregation in schools, the gaping racial disparities in income and wealth, and the damage done to black families by the U.S. criminal justice system.

25 million students are in school districts that aren't integrated, or are too homogenous to integrate. Over the past couple of decades, integration took hold across the country in smaller school districts whose student bodies had been predominantly white. But in many big cities and across the South, students remain in districts that are deeply segregated.

Coming of age in a city coming apart: Renaissance Academy had seen too many of Baltimore's black boys derailed or destroyed by the mayhem around them. If they could help it, Khalil Bridges would not be one of them. In him, they saw promise, a young man who could graduate in June and go on to find success. Can he make it when others are dying?

Protest and activism

How the Black Lives Matter movement went mainstream: As consensus grows about the existence of systemic racism in American policing and other facets of American life, longtime organizers of the Black Lives Matter movement are trying to extend its momentum beyond the popularization of a phrase. Activists sense a once-in-a-generation opportunity to demand policy changes that once seemed far-fetched, including sharp cuts to police budgets in favor of social programs, and greater accountability for officers who kill residents.

"The moment I was first placed under arrest at a sit-in, I felt free." Congressman John Lewis (D-Ga.) was a student leader in the civil rights movement, organizing sit-ins and serving as one of the original 13 Freedom Riders. From 1963 to 1966, Lewis was chairman of the Student Nonviolent Coordinating Committee (SNCC). He has served in Congress from 1987 until his death in July. Photos: Remembering John Lewis

"We have the responsibility to bring some level of concrete change to this moment." Al Sharpton and Martin Luther King III hope to re-create the power of the 1963 March on Washington. After months of spontaneous local protests, will a national march speak to a new generation?

Perspective: "Sixty years ago, I participated in the civil rights movement to bring about the same kind of changes being sought by Black Lives Matter activists today." Joyce Ladner says racist violence in the South was the catalyst for her generation, and she's angry that 60 years later black men and boys are still being killed by police and vigilantes.

Minorities make up nearly half of the under-30 population nationwide. The number of young people of color living in the Midwest has surged over the past decade, as the older white population has nearly stalled. Forty percent of the nation's counties are experiencing such demographic transformations - a phenomenon fueling the Black Lives Matter protests that have swept the country.

Opinions: Voices of the Movement: This audio series from the "Cape Up" podcast brings you the stories and reflections of some of the leaders of the civil rights movement, and their lessons on where we go from here.

Perspective: This is why Colin Kaepernick took a knee: Two knees. One protesting in the grass, one pressing on the back of a man's neck. Choose. You have to choose which knee you will defend. There are no half choices; there is no room for indifference. There is only the knee of protest or the knee on the neck.

Voices of Protest: From veterans of the civil rights movement to college students protesting for the first time, many say they were moved to take part because this moment feels different. The Washington Post reached out to readers to ask them why they participated in the protests and what they hope will come out of it.

Income inequality

The Chicago metropolitan area has remained one of the most segregated regions in the United States since 1990. Some 50 years ago, policies like the Fair Housing Act and the Voting Rights Act were enacted to increase integration, promote equity, combat discrimination and dismantle the lingering legacy of Jim Crow laws. But a Washington Post analysis shows that some cities remain deeply segregated - even as the country itself becomes more diverse.

"The only way African American businesses are going to survive is we have to own our own stuff." The coronavirus recession could wipe out minority-owned businesses, fueling displacement from historic ethnic neighborhoods.

In the first quarter of 2020, 44 percent of black families owned their home, compared with 73.7 percent of white families. Mary Pherribo's decision to buy a home in 1936 changed the trajectory of her family's finances for generations. Today, that pattern of homeownership and generational wealth building is broken for many black families.

An abrupt change to the census deadline could result in an undercount of Latino and Black communities. The decennial census is not just about the count, but also allocating federal resources and apportioning congressional seats. "As Covid continues to rip through those communities, it is a very challenging thing to see communities that absolutely need resources that could be left out."

3 out of 4 neighborhoods "redlined" on government maps 80 years ago continue to struggle economically. In the 1930s, government surveyors graded neighborhoods in 239 cities, color-coding them green for "best," blue for "still desirable," yellow for "definitely declining" and red for "hazardous." The "redlined" areas were the ones local lenders discounted as credit risks, in large part because of the residents' racial and ethnic demographics.

The black-white economic divide is as wide as it was in 1968. The wealth gap is even more pronounced among less-educated Americans. A white household whose head has only a high school diploma has almost 10 times the wealth of a black family with the same education.

Only 1 percent of venture capital money goes to companies founded by black entrepreneurs. Black entrepreneurs said complaining about race discrimination, let alone hiring a lawyer and taking action, would amount to a career death sentence.

Nationwide, home values in predominantly African American neighborhoods were the least likely to recover from the Great Recession. Across the country, blacks are less likely to own homes; those who did were more likely during the housing bust to slip underwater; and as a result, a larger share of black wealth has been destroyed in the years since then.

Perspective: The rate of black unemployment is consistently about twice that of both the white rate and the overall rate. The Federal Reserve could help make the job market fairer for black workers.

The dangers of internalizing racism: Racism hurts. A growing body of research shows it negatively affects the mental and physical health of its victims. Like any burden, it wears the bearer down. Sometimes it makes you feel like lashing out. Sometimes it makes you feel as if you are drowning.

Black and Latinx Americans are two to three times more likely than white Americans to be uninsured. The coronavirus has laid bare the staggering costs of decades of disinvestment and inadequate care of minority communities across the country and the desperate need to collect and measure the impact of the disease as it pertains to race. Explore chronic health rates in your community.

Black Americans die younger than white Americans. The protests over the deaths of black men and women at the hands of police have turned attention to other American institutions, including health care, where some members of the profession are calling for transformation of a system they say results in poorer health for black Americans because of deep-rooted racism.

"I had to read an article about black motherhood that wasn't a horror story." Women of color have the highest rates of maternal death. Black mothers are among the most at risk no matter their socioeconomic or educational status. How were pregnant black women navigating the dreaded numbers? How were they experiencing joy? How were they scrolling past the scary headlines and instead sharing stories of uplift?

How to balance activism with your mental health: George Floyd's death is a traumatic experience for black people all across America and the world. But it's retraumatizing, too, because black people deal with racism every day. We asked community organizers how that manifests itself in their daily lives and in the work that they do.

What can a scholarship do to address a historic injustice? For Morgan Carter and her family, reparations changed the frame of a tortured past. The Florida legislature passed a law in 1994 allowing descendants of the Rosewood massacre to go to college in the state tuition-free. The law is regarded as the first instance of a legislative body in the United States giving reparations to African Americans.

The Deltas helped pave the way for African American women in politics. Women at Howard University formed the Delta Sigma Theta sorority in 1913 and faced racism in the suffrage movement but refused to walk away.

More Black women are running for Congress in the 2020 cycle than ever before. One hundred years after women gained the right to vote, they remain underrepresented in the halls of power. Women of color make up about one-fifth of the U.S. population but a far smaller share of major elective offices.

3 in 4 black adults say they are certain to vote in November. Black Americans say racism and police conduct are the most important issues in their choice of candidates for president, are sharply critical of President Trump on both matters and see increasingly high stakes in the outcome of November's election.

"Wading into racial politics energizes Democrats." American politics has arrived at this moment of racial reckoning deeply polarized and with a party structure shaped profoundly by the politics of race. From calls to defund the police to the issue of reparations to ideas for more race-conscious policies, the possible agenda to address racial issues is expansive and challenging - and potentially still more wrenching - than the country is prepared to address.

Opinions: "To be white in America ... means to have to block the advances of other groups." Jonathan Metzl talks to Opinion writer Jonathan Capehart about how people are "dying of whiteness" rather than support policies they view as also helping minorities.

At Howard, the story of black Americans was not relegated to a single African American Studies department. It was central to everything. Sen. Kamala D. Harris made history becoming the first woman of color to be on a major-party presidential ticket. When anyone challenges her racial identity, Harris points to her four years at Howard University. See her career in photos.

Policing and criminal justice

Black Americans are disproportionately killed by police. Black Americans account for just 13 percent of the U.S. population, but more than a quarter of police shooting victims. The disparity is even more pronounced among unarmed victims, of whom more than a third are black. Search The Post's police shooting database.

In urban areas, police are consistently much whiter than the people they serve. A University of Maryland criminologist found that crime rates in minority neighborhoods are lower when local police and government diversity matches the community.

"His greatest fear was that I would become a traitor." This is the struggle of black police officers, then and now. They sign up for a job that offers a path to a middle-class life and a chance to honor their communities by pledging to protect them, but they can face questions of loyalty from neighbors who are skeptical of law enforcement.

Opinions: Incarceration rates of African Americans in general remain 5.6 times greater than those of white Americans. Black people are about 12 percent of the U.S. population, but one-third of the inmate population.

Opinions: "Why I can't watch the police videos anymore": A 2017 National Institutes of Health study noted that the psychological impact on black people of the proliferation of videos of us as victims of police lethality is that we see our lives as "disposable, and undeserving of dignity and justice."

No arrests were made in the homicides of more than 18,600 black men and women. Black victims, who accounted for the majority of homicides, were the least likely of any racial group to have their killings result in an arrest.

"I'm not just the guy in the video." Former NFL player Desmond Marrow's arrest was caught on a video that went viral in April 2018. As he revisits the scene of where the incident occurred, he reflects on the ways the encounter had an impact on him.

The first black president: The Obama victory helped fulfill one of the great ambitions of the civil rights struggle by showcasing the ability of extraordinarily talented black Americans to lead and excel in all facets of American life. Explore a virtual museum of Obama's presidency.

My father taught me about Black food and identity. Now that he's gone, cookbooks fill the gap. Cookbooks prompted me to consider the legacy of food beyond its role as a survival mechanism. For people who have so often struggled at the margins, food remains an important means for providing care.

Tour through the National Museum of African American History and Culture: Underground, a stark path winds chronologically and unflinchingly from slavery through civil rights and beyond. Aboveground, bold, busy galleries celebrate some of the cultural contributions African Americans have made to the country and the world.

"We don't often get the layers we need to tell our stories in contemporary ways." The Washington Post spoke to several black writers about their experiences in the television industry. Most remain cautiously optimistic about whether these companies will eventually look inward. It's not just the dearth of opportunity the writers say has hurt them - though that is certainly the first hurdle - but also the lack of upward mobility once they're in the room.

"Am I going to have the experience that I want, which is to be free of race and to enjoy this moment? Or will race tap me on the shoulder?" Motorists still fear encountering racist police officers or wandering into towns where they're not welcome. Social media also gives a sense of what domestic travel looks like through the eyes of a person of color, chronicling stories of discriminatory encounters with such hashtags as #AirbnbWhileBlack and #TravelingWhileBlack.

Black chefs say discrimination and restricted upward mobility make it difficult for them to achieve success. Edouardo Jordan went to culinary school to be a chef, he said, not to be a black chef. To avoid being pigeonholed early in his career, he strayed from the Southern fare he found most familiar and instead pursued Italian and French cuisines - two of the most popular in fine dining.

In 'Black Panther,' a superhero who finally looks like me. "Black Panther" brings to life Marvel's greatest black superhero. For The Post's David Betancourt, this has been a long time coming.

Perspective: "I know the freedom of moving through a world that magically removes many barriers from my life and shields me from harm - all because of my ability to pass as white." Even as I continue to reap its benefits, I am ashamed of the white privilege I carry around because I know it comes at the expense of others who have every right to the same opportunities, advantages and freedoms.

"Publishing is still a business that is owned by white men": Post Reports host Martine Powers talks with N.K. Jemisin, Jasmine Guillory and Lauren Wilkinson about challenging narrow perceptions of race in literary genres.

"What we say about race, what we do about race, in each moment, determines what - not who - we are." Historian Ibram X. Kendi has daring, novel ideas about the nature of racism - and how to fight it.

Redefining the n-word: As the National Football League wrestled with banning the word on the field, a team of Washington Post journalists examined the history of this singular American word, its spread through popular culture and its place in the vernacular today.

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Resources to understand America's long history of injustice and inequality

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The video of George Floyd's death at the hands of police in Minneapolis triggered protests around the world. It brought renewed attention to the high-profile deaths of black Americans during the past decade and ongoing concerns about systemic racism in the criminal justice system.

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I hope we are at the tipping point of addressing and ending endemic racism.

Then again, I thought so during the Civil Rights movement.

Racism is a topic so hot you have to hold it with oven mitts.

The evil of piping-hot racism has been the curse of mankind seemingly forever.

It wraps around people like a wet towel and smothers their intelligence and literally colors their perception.

Racism creates foolish dissonance and discord. It populates us with a bunch of jammers who have no hope of ever morphing into a symphony orchestra tuned to the belief that all men are created equal.

All this molten hatred served in a cast-iron skillet is all so insane and such a colossal waste.

Humans think they are so smart.

Guess what?

Sometimes they are as dumb as a fire plug. Thicker than concrete.

Especially racist humans. Their myopic focus is only skin deep.

If you think about it, racism is totally absurd.

It is all based on skin pigmentation. Variations in human skin color are adaptive traits that correlate closely with geography and the sun's ultraviolet (UV) radiation.

Which is why people whose ancestors are from the tropics generally have darker skin.

People are people and skin color makes them no different from each other - unless they see it as so.

All the racial hatred over generations comes down to negative attitudes toward people whose melanin levels differ from theirs.

In God's name, how stupid is that? And how tragic is that?

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If race is only skin deep, why does racism go down to the bone? | BCTV

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I hope we are at the tipping point of addressing and ending endemic racism. Then again, I thought so during the Civil Rights movement. Racism is a topic so hot you have to hold it with oven mitts. The evil of piping-hot racism has been the curse of mankind seemingly forever.

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Americans were living through history in 2020 as the country was forced to reconcile the past and the present. The Covid-19 pandemic, which many had considered a "great equalizer," paralyzed the world and Black, Latino and Native American communities were among the hardest hit. Racist attacks against Asians in the US were also on the rise. Jogging, bird-watching or calling 911 while Black felt dangerous and George Floyd 's killing by a police officer shook Americans out of whatever made them numb to racism and police brutality.

No matter where you turned, you couldn't ignore reality. America was the epicenter of a racial reckoning.

Within days, people joined more than 10,000 demonstrations nationwide and a movement to demand reform in police departments across the country quickly followed. Confederate monuments were toppled. TV and sports arenas were not exempt from the call for social justice, and athletes were among the leading voices in the fight for racial equality.

Throughout the year, US law enforcement warned about a growing threat and concern that the rise of White supremacist groups had become the biggest domestic terrorism challenge.

By November, people turned from protesting in the streets to protesting at the polls and Black, Latino and Native Americans voters helped flipped some states blue.

Look back at the moments in politics, policing and culture that defined the extraordinary year in which America was forced to confront racism - and in some cases moved the needle toward change.

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Year in review. As the Covid-19 pandemic ravaged the US, Black, Latino and Native Americans were among the hardest hit and Asians became the targets of racist attacks in 2020. The killings of George Floyd and others reignited the outcry that Black Lives Matter and thousands protested across the US.

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Gun control is back in the U.S. political debate, in the wake of mass shootings in California, Boulder and Atlanta.

Democrats see stricter gun control as a step toward addressing the problem. In March 2021, as the House of Representatives passed two gun control bills, Speaker Nancy Pelosi claimed that the " solutions will save lives."

Many Republicans disagree, arguing as Sen. Ted Cruz has that proposed laws seeking to require background checks on all firearms sales and transfers and to ban assault weapons are " ridiculous theater " that fail to reduce mass shootings.

As two political scientists trained in data analysis, we set out to determine whether gun control legislation actually prevents mass shootings. We collected data on all mass shootings that occurred between February 1980 and February 2020. We then examined key information on the perpetrators, weapons used and laws in effect at the time of shooting.

Our research, which is yet to be published in an academic journal, suggests that there is statistical evidence to support both parties' positions about gun control legislation.

While stricter gun control laws may make mass shootings slightly less common, our research suggests that the rhetoric of both parties may not tell the full story. Rather than federal gun control laws, policies that focus on violence prevention at the community or individual levels may be more effective at preventing mass shooting deaths.

Mass shootings in the past 40 years

We defined a mass shooting as a single incident in which a perpetrator with no connection to gang activity or organized crime shot and killed three or more people. This is similar to the definition Congress uses.

We found there were 112 of these events between 1980 and 2020; the number of mass shootings each year has increased over time. An overwhelming majority of mass shooters - 87% of them - obtained their firearms legally. Nearly all shooters - 93% - shot their victims in the same state where they obtained their weapons.

These facts suggest that existing gun laws and regulations governing gun purchases and firearms that cross state lines may not be working to reduce mass shootings. Our study did not address whether or how other forms of gun violence might be affected by those laws.

In fact, mass shootings tended to occur in states with stricter regulations. Of the states with the highest per capita rates of mass shootings, many - like Connecticut, Maryland and California - employ background checks and assault weapons bans.

By contrast, 18 states did not have a single mass shooting event over the entire 40-year period. Many of these states - like West Virginia, Wyoming and South Dakota - have high rates of gun ownership and relatively loose gun control laws.

But those data patterns don't tell the full story of our analysis.

The effects of gun laws

Gun laws aren't the only factors that affect where and when mass shootings occur. The number of police officers per capita, a community's population density and crime rate, and other demographic characteristics such as unemployment rates and average income can also matter.

We used statistical methods to control for those factors, narrowing our analysis to find out whether various types of gun control laws affected the number of mass shootings or number of mass shooting deaths in each state each year.

Specifically, we examined the effects of four different types of gun control legislation: background checks; assault weapons bans; high-capacity magazine bans; and " extreme risk protection order " or "red flag laws" that let a court determine whether to confiscate the guns of someone deemed a threat to themselves or others.

We found that background check requirements, assault weapons bans and high-capacity magazine bans each reduce the number of mass shootings in the United States - but only by a small amount. For instance, enacting a statewide assault weapons ban decreases the number of mass shootings in the state by one shooting every six years. And none of the four types of gun control legislation correlate with fewer total mass shooting deaths.

And laws that remove an individual's right to own firearms if that individual poses a risk to the community do not affect the number of mass shooting events.

Beyond gun control

Our analysis suggests that Americans who want to make mass shootings less frequent and less deadly may want to think beyond gun control legislation.

Statistically, mass shootings tend to occur in large, densely populated states with higher income and education levels per capita. While these states often respond to mass shootings by passing gun control legislation, it may be that alternative avenues are more successful.

For example, we find that increasing the number of police officers per capita decreases the number of mass shootings.

There is a wide variety of policy options designed to prevent mass shootings. The American Psychological Association suggests a comprehensive community approach that works to identify prevention strategies that bring public safety officials, schools, public health systems and faith-based groups together to reduce gun violence.

Aaron Stark, who says he was almost a mass shooter, explains that mass shootings can be an act of desperation resulting from frustration, stress and an individual's perception that they lack power. This is in line with a new U.S. Secret Service report that suggests politicians may need to think beyond the accessibility of guns. Violence prevention strategies that focus on interpersonal and community relations may be more effective than gun control legislation.

Framing the debate

Many policy options involve value judgments stemming from beliefs about the U.S. Constitution and the power of government to regulate guns.

Among people who think that restricting gun access reduces mass shootings, people disagree over whether the country should prioritize the individual freedoms of gun owners or the safety and peace of mind of non-gun owners. These differing views can reflect different interpretations of the extent to which the Constitution protects the rights of individuals to keep and bear arms.

States have a role to play, too. Federal gun policy covers the entire nation. But our data indicates that attention to state and local factors can play an important role in preventing mass shootings.

In the end, gun control remains a debate about facts and context, complicated by a disagreement over constitutional values.

[ Get the best of The Conversation, every weekend. Sign up for our weekly newsletter.]

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In gun debate, both sides have evidence to back them up

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Gun control is back in the U.S. political debate, in the wake of mass shootings in California, Boulder and Atlanta. Democrats see stricter gun control as a step toward addressing the problem. In March 2021, as the House of Representatives passed two gun control bills, Speaker Nancy Pelosi claimed that the " solutions will save lives."

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Gun violence in America is at a crisis point. Every day, more than 110 people are killed from guns and more than 200 are shot and wounded.

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Law enforcement agencies implement a variety of strategies and methods to combat crime and ensure public safety. Policing strategies extend beyond traditional models of responding to calls for service and often seek to increase crime prevention, intervention, and response effectiveness through such techniques that focus on gun violence prevention and intervention. These strategies are aimed at reducing gun-related crimes and homicides in neighborhoods and communities.

NIJ has funded research and evaluation projects to understand and address the issues of gun violence and gun violence prevention since the late 1990s.

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Law enforcement agencies implement a variety of strategies and methods to combat crime and ensure public safety. Policing strategies extend beyond traditional models of responding to calls for service and often seek to increase crime prevention, intervention, and response effectiveness through such techniques that focus on gun violence prevention and intervention.

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The struggle of LGBT (lesbian, gay, bisexual and transgender) people for equal rights has moved to center stage. LGBT people are battling for their civil rights in Congress, in courtrooms and in the streets. Well-known figures are discussing their sexual orientation in public. Gay and lesbian people are featured in movies and on television - not as novelty characters, but as full participants in society.

Despite these advances into the American mainstream, however, LGBT people continue to face real discrimination in all areas of life. No federal law prevents a person from being fired or refused a job on the basis of sexual orientation. The nation's largest employer - the U.S. military - openly discriminates against gays and lesbians. Mothers and fathers lose child custody simply because they are gay or lesbian, and gay people are denied the right to marry.

One state even tried to fence lesbians and gay men out of the process used to pass laws. In 1992 Colorado enacted Amendment 2, which repealed existing state laws and barred future laws protecting lesbians, gay men and bisexuals from discrimination. The U. S. Supreme Court struck it down in the landmark 1996 Romer v. Evans decision.

We must conclude that Amendment 2 classifies homosexuals not to further a proper legislative end but to make them unequal to everyone else. This Colorado cannot do. A State cannot so deem a class of persons a stranger to its laws.
-- Justice Anthony Kennedy
Majority Opinion in Romer v. Evans I

The modern gay rights movement began dramatically in June 1969 in New York City's Greenwich Village. During a typical "raid," police tried to arrest people for their mere presence at a gay bar, but the patrons of the Stonewall Inn fought back - and the gay rights movement was launched. Using many of the grass-roots and litigation strategies employed by other 20th century activists, gay rights advocates have achieved significant progress:

Ten states, the District of Columbia, many municipalities and hundreds of businesses and universities now ban employment discrimination.

"Domestic Partnership" programs exist in dozens of municipalities and hundreds of private institutions, including many of the country's largest corporations and universities.

Sodomy laws, typically used to justify discrimination against gay people, once existed nationwide; they are now on the books in only 18 states and Puerto Rico.

But the increased empowerment of LGBT people has brought about even more open and virulent anti-gay hostility:

Although unrelated to an individual's ability, sexual orientation can still be the basis for employment decisions in both the public and private sectors in most states and municipalities.

Violent hate crimes, such as the 1998 murder of Wyoming student Matthew Shepherd, depict a grisly backlash against LGBTs or people perceived to be gay.

LGBT students and teachers face daily harassment and discrimination in the schools, and LGBT student groups in high schools and colleges still face roadblocks.

In 1986, after more than two decades of support for lesbian and gay struggles, the American Civil Liberties Union established a national Lesbian and Gay Rights Project. Working in close collaboration with the ACLU's affiliates nationwide, the Project coordinates the most extensive gay rights legal program in the nation. Increasing opposition from a well-organized, well-funded coalition of radical extremists and fundamentalists promises many battles and challenges ahead.
WHAT IS THE CONSTITUTIONAL BASIS FOR LGBT EQUALITY?
The struggle for legal equality for LGBT people rests on several fundamental constitutional principles.
Equal protection of the law is guaranteed by the Fifth and Fourteenth Amendments and reinforced by hundreds of local, state and federal civil rights laws. Although the Fourteenth Amendment, ratified at the end of the Civil War, was designed to ensure legal equality for African Americans, Congress wrote it as a general guarantee of equality, and the courts have interpreted the Equal Protection Clause to prohibit discrimination on the basis of gender, religion and disability. The ACLU believes the Equal Protection Cluase prohibits discrimination based on sexual orientation as well. The right to privacy, or "the right to be left alone," is guaranteed by the Fourth, Fifth, Ninth and Fourteenth Amendments. In 1965, Griswold v. Connecticut struck down a state law that prohibited married couples from obtaining contraceptives, citing "zones of privacy." In 1967, Loving v. Virginia decriminalized interracial marriage. The 1972 Eisenstadt v. Baird decision recognized unmarried persons' right to contraceptives. And in 1973, Roe v. Wade recognized women's right to reproductive choice. All of these Supreme Court decisions underscore the principle that decisions about intimate relationships are personal and should be left up to the individual. Freedom of speech and association are protected under the First Amendment. This Amendment protects the right to organize and urge government to end discrimination, to recognize lesbian and gay relationships, and to adopt laws prohibiting discrimination in the private sector. It also includes the rights to form social and political organizations, to socialize in bars and restaurants, to march or protest peacefully, to produce art with gay themes and to speak out publicly about LGBT issues.

In the Schools

Nothing is more important than making schools safe and welcoming places for gay and lesbian youth, who often face tremendous hostility from their family and community during their formative years. This means protecting students from violence, guaranteeing their right to organize events and clubs like other students, and making sure that gay teachers who might serve as healthy role models are not themselves victimized by discrimination. The ACLU has fought harassment of students in California, Nevada, Ohio and Washington, defended gay teachers in California, Idaho and Utah, and advocated for gay student groups in Alabama, Indiana, Minnesota, Utah and Wisconsin.
Harassment on the job
Mary Jo Davis had high hopes when she accepted a job offer with the Radiology Department of Pullman Memorial Hospital in Whitman County, Washington. All that changed after her supervising doctor discovered she was a lesbian. The doctor started calling her a "dyke" and "faggot," and wouldn't work with her or even speak to her. When Mary Jo protested this harassment, she was fired. Represented by the ACLU's Lesbian and Gay Rights Project, Mary Jo hopes to establish that public employees have a constitutional right to be free from discrimination and harassment in the workplace.
Sodomy and Homophobia
David Weigand could take it no longer. His son was living in the home of his former wife, along with the boy's stepfather - a convicted felon with a drinking and drug problem who was beating his wife in the presence of the child. Things got so bad that the boy had to call 911 to save his mother's life, and as a result of all the violence, the family was ultimately evicted from their home.

David asked a Mississippi family court to give him custody of his son. The court refused to do so, in essence saying that living in a home wracked with violence was preferable to living with a father who is gay and "commits sodomy." In addition to representing David before the Mississippi Supreme Court, the ACLU will continue fighting on behalf of lesbian and gay parents, and to eliminate state sodomy laws.
In the Child's Best Interest
States are supposed to make rules on adoption and foster care to protect the best interest of children in need of loving homes and families. But somehow it does not work out that way in states like Florida and Arkansas, which ban gays and lesbians from adopting and being foster parents, respectively. By challenging the discriminatory policies of these states, the ACLU is working hard to prevent similar policies from being adopted in other parts of the country.

As a reminder of what is supposed to be the essence of child-welfare policy, the ACLU's Lesbian and Gay Rights Project in 1998 published a report entitled In the Child's Best Interest: Defending Fair and Sensible Adoption Policies. To order this, the 1998 videotape Created Equal about employment discrimination against LGBTs, or any other ACLU publication, please contact ACLU Publications at 1-800-775-ACLU.

AREN'T LGBT PEOPLE DEMANDING SPECIAL RIGHTS AND PREFERENTIAL TREATMENT?
As the Supreme Court explained in Romer v. Evans, there is nothing "special" about laws which prevent people from losing jobs and homes because of who they are. Most of us take the right to participate in daily life on an equal footing for granted, the Court said, either because we already have the right under the law, or because we are not subjected to that kind of discrimination. Laws which prohibit discrimination simply give LGBT people that basic right to be equal participants in the communities in which they live.

Most Americans do not realize that many LGBT people who face discrimination - in areas from housing and employment to parenting - have no legal recourse since federal law does not prohibit discrimination against LGBT people. Extending such protection from discrimination to LGBT people is one of the many important battles ahead for the ACLU and other advocacy organizations.

ARE LGBT PEOPLE PROTECTED AGAINST DISCRIMINATION ANYWHERE IN THE COUNTRY?

Yes, twelve states (California, Connecticut, Hawaii, Maryland, Massachusetts, Minnesota, New Hampshire, Nevada, New Jersey, Rhode Island, Vermont and Wisconsin), the District of Columbia, many municipalities, and hundreds of businesses and universities have enacted laws that protect gay, lesbian and bisexual people from employment discrimination. A smaller number of jurisdictions protect transgender people.

But in most locales in the remaining 38 states discrimination against LGBT people remains perfectly legal. Businesses openly fire LGBT employees, and every year, lesbian and gay Americans are denied jobs and access to housing, hotels and other public accommodations. Many more are forced to hide their lives, deny their families and lie about their loved ones just to get by.

The ACLU believes the best way to redress discrimination is to amend all existing federal, state and local civil rights laws and all existing business and university policies to ban discrimination based on sexual orientation.
WHAT ABOUT DOMESTIC PARTNERSHIPS?
Many cities, including New York, Los Angeles, San Francisco, Atlanta, the District of Columbia and Minneapolis, have created "domestic partnership" registries. They give official status to same-sex couples who register with the city. Scores of government and private companies recognize the domestic partnerships of their employees. The state of Hawaii recognizes domestic partners.

While these laws do not confer most of the rights and responsibilities of marriage, they generally grant partners some of the recognition accorded to married couples - typically, the right to visit a sick or dying partner in a hospital, sometimes sick and bereavement leave and in a few cases, health insurance and other important benefits.

Perhaps as important, these policies give some small acknowledgement to the intimate, committed relationships central to the lives of so many lesbians and gay men, which society otherwise ignores.
WHY SUPPORT SAME SEX MARRIAGE?
Denying lesbian and gay couples the right to wed not only deprives them of the social and spiritual significance of marriage; it has serious, often tragic, practical consequences. Since they can not marry, the partners of lesbians and gay men are not next of kin in times of crisis; they are not consulted on crucial medical decisions; they are not given leave to care for each other; they are not each other's legal heirs, if, like most Americans, they do not have wills. Marital status is often the basis on which employers extend health insurance, pension and other benefits. The ACLU believes that since we have attached such enormous social consequences to marriage, it violates equal protection of the law to deny lesbian and gay couples the right to wed.

WHAT ARE "SODOMY LAWS" AND WHY BOTHER WORKING TO REPEAL THEM?

Sodomy statutes generally prohibit oral and anal sex, even between consenting adults. Penalties for violating sodomy laws range from a $200 fine to 20 years imprisonment. While most sodomy laws apply to both heterosexuals and lesbians and gay men, they are primarily used against gay people. For example, some courts say sodomy laws justify separating gay parents from their children. Some cities use sodomy laws to arrest gay people for talking with each other about sex, in conversations which parallel those heterosexuals have every day.

In recent years, the legislatures of Pennsylvania, Nevada and Rhode Island joined the 23 other state legislatures which repealed sodomy laws in the 60s and 70s. Courts in Georgia, Kentucky, Maryland, Montana and Tennessee have struck down the statutes. The remaining sodomy laws will be challenged in the legislatures and the courts until they are all eliminated.

"We must conclude that Amendment 2 classifies homosexuals not to further a proper legislative end but to make them unequal to everyone else. This Colorado cannot do. A State cannot so deem a class of persons a stranger to its laws."

- Justice Anthony Kennedy
Majority Opinion in Romer v. Evans

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The Rights of Lesbian, Gay, Bisexual and Transgender People

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The struggle of LGBT (lesbian, gay, bisexual and transgender) people for equal rights has moved to center stage. LGBT people are battling for their civil rights in Congress, in courtrooms and in the streets. Well-known figures are discussing their sexual orientation in public.

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Introduction

There have always been homeless people in the United States. As economic circumstances and demographic forces have fluctuated, so have the size and composition of the homeless population, although relatively permanent skid rows where homeless people congregate have long been a feature of many large cities.

In the past decade, however, the problem of homelessness has increasingly captured public attention. Not only has the number of homeless people increased dramatically within the last several years but the composition of the homeless population has also changed appreciably during that period: For example, middle-aged men make up a shrinking fraction of all homeless people, and families with young children are the fastest growing component of the homeless population (U.S. Conference of Mayors, 1987). Growing public awareness of homelessness is also connected to changes in the geographic dispersion of homeless people, who are becoming more visible in neighborhoods and communities that would not have imagined their presence in the past.

This chapter briefly describes homelessness in the United States. It begins by defining homelessness, assessing methodologies used to count homeless people, and reviewing recent scholarly literature on the subject. The chapter continues by examining the socio-demographic characteristic s of homeless people, with emphasis on adult individuals, families and children, runaway and throwaway youths, the elderly, and people in rural areas. In the course of this discussion the issues relating to the prevalence of health and mental health problems inevitably arise, but these are reviewed in greater detail in Chapter 3, Health Problems of Homeless People.

Definition of Homeless

For the purpose of this report, the definition of homeless or homeless person is the same as that in P.L. 100-77, the Stewart B. McKinney Homeless Assistance Act, enacted in July 1987 (U.S. Congress, House, 1987):

(1)

an individual who lacks a fixed, regular, and adequate nighttime residence: [or]

(2)

an individual who has a primary nighttime residence that is-

(A)

a supervised or publicly operated shelter designed to provide temporary living accommodations (including welfare hotels, congregate shelters, and transitional housing for the mentally ill);

(B)

an institution that provides a temporary residence for individuals intended to be institutionalized; or

(C)

a public or private place not designed for, or ordinarily used as, a regular sleeping accommodation for human beings.

This definition refers specifically to homeless individuals, but it is equally applicable to homeless families.

Counting the Homeless

Even within the framework of a relatively straightforward definition, there is considerable uncertainty about the number of people who are homeless at any given time in the United States. Conventional methods of enumerating populations, such as the census, are based upon counting people where they live. Not only do people move in and out of homelessness but the methodological problems involved in counting people without a fixed residence are formidable. Studies that have attempted to count homeless people have been subject to severe criticism. For example, samples are generally small and may not be generalizable to other locales, data are often collected from single sites, samples often are not systematically drawn, measures and definitions of homelessness are inconsistent, and the rural population is virtually unidentified. For all these reasons, the various studies cannot be easily compared or generalized. ( Appendix B of this report contains a detailed analysis of the three most common methods of counting homeless people and the technical strengths and weaknesses of each.)

The range of estimates of the number of homeless people is wide ( Table 1-1). At the low end is the U.S. Department of Housing and Urban Development (1984) estimate of 200,000 to 300,000. At the high end are advocates' estimates of more than 2 million (Hombs and Snyder, 1982). Whatever the absolute numbers, the number of homeless people has grown appreciably in recent years. Surveys conducted by the U.S. Conference of Mayors in 25 representative cities in each of the past 2 years identified no city in which the numbers were falling; most cities reported annual increases of 15 to 50 percent (U. S. Conference of Mayors, 1987). A substantial majority of the cities reported that families were the fastest growing component of the homeless population. One recent estimate of the number of homeless people in the United States, published in June 1988 by the National Alliance to End Homelessness, calculates that currently, on any given night, there are 735,000 homeless people in the United States; that during the course of 1988, 1.3 million to 2.0 million people will be homeless for one or more nights; and that these people are among approximately 6 million Americans who, because of their disproportionately high expenditures for housing costs, are at extreme risk of becoming homeless (Alliance Housing Council, 1988).

For the purposes of this study, the question of precisely how many homeless people there are was not of central importance because homelessness is not a static condition; poor people move in and out of a state of homelessness. Therefore, the committee devoted a major part of its effort to analyzing the composition of the homeless subpopulations and the health-related needs of each group.

Studies of Homelessness

Since the early 1980s, an extensive body of literature about homeless people has emerged. Although some have described homelessness in the United States impressionistically, a number of scholars have conducted substantial surveys and performed extensive data analyses in order to describe the characteristics of homeless people. The earliest publications on the "new" homeless have focused on the demographic and social characteristics of homeless adults living in large cities, such as New York (Hoffman et al., 1982; Crystal and Goldstein, 1984), Phoenix (Brown et al., 1982, 1983), Portland, Oregon (Multnomah County, Oregon, Department of Human Services, 1984, 1985), Los Angeles (Robertson et al., 1985; Farr et al., 1986), Chicago (Stevens et al., 1983; Rossi et al., 1986), St. Louis (Morse et al., 1985), Milwaukee (Rosnow et al., 1985), Boston (Bassuk et al., 1984), Philadelphia (Arce et al., 1983), and Baltimore (Fischer and Breakey, 1986). Wider in geographic scope are the studies of the states of Ohio (Roth et al., 1985) and Vermont (Vermont Department of Human Services, 1985). Although the sites at which data were collected often differed-shelters, streets, single room occupancy hotels-as did the sampling strategy and operational criteria for studying homelessness, the data collected from these different areas showed surprising similarities. Research has also been conducted on subpopulations of homeless people as well as on specialized topics related to homelessness. A substantial number of reports have focused on the homeless mentally ill and on homeless people who suffer from alcohol abuse. A much smaller body of literature exists on other health-related issues. In fact, it was only 3 years ago that the first book on this issue, Health Care of Homeless People (Brickner et al., 1985), was published; the importance of the issue and the growth in our knowledge are reflected by the fact that the authors already have begun work on the second edition. There is also a growing body of scholarly work on subpopulations, especially homeless families (Bassuk et al., 1986).

Studies on the demographic and social characteristics of the homeless in the United States have almost always been based upon research conducted in urban areas. Except for the Ohio and Vermont reports, which included both urban and nonurban areas, very little has been published on the homeless in suburban and rural communities-xcept in newspapers (Washington Post, September 27, 1987; New York Times, October 16, 1987). There is a similar, though less pronounced, paucity of information about certain subpopulations among the contemporary homeless, such as the elderly, youths, individual adult women, the physically disabled, the mentally retarded, and those addicted to illicit drugs.

Characteristics of Homeless People

Homeless people are a diverse and varied group in terms of age, ethnicity, family circumstances, and health problems. Moreover, the characteristics of the homeless population differ dramatically from one community to another. Even the recent increase in homeless families is not uniform throughout the country. Although homeless families headed by women are predominant among the homeless throughout the country, there are many more homeless two-parent families in the West and Southwest than in New York and other large eastern cities (U.S. Conference of Mayors, 1987). Every city has homeless adults, but the demographics are not uniform throughout the country. Most cities report that adult homeless men tend to be long-term residents of the city. However, during a site visit to San Diego, committee members were informed by both public officials and advocates for the homeless that San Diego's adult homeless male population was composed largely of young men from the West and Midwest who had come to the Southwest in search of jobs.

To make the needs of homeless people more understandable, we describe several subgroups separately: individual adult men and women, families with children, youths, the elderly, and people in rural areas.

Homeless Individual Adults

Although families may represent the fastest growing subgroup among the homeless, individual adults still make up the single largest group among the homeless population. The documented characteristics of homeless adult men and women contradict some popular conceptions of what such people are like.

The U.S. Conference of Mayors (1987) reported that individual men made up 56 percent of the homeless population and individual women made up 25 percent. (The remainder are adolescents or families with children.) Of the 25 cities in the study, 7 reported recent increases in the numbers of homeless women. In 1963, homeless women represented only 3 percent of the homeless population (Bogue, 1963). Researchers indicate that a high proportion of homeless women suffer from serious problems including chronic mental illness and pregnancy-related problems (Wright, 1987; Wright and Weber, 1987; Wright et al., 1987). In addition, homeless women are frequently victims of physical assault, especially rape (Brickner et al., 1985).

Individual homeless men and women have an average age of between 34 and 37 (Morse, 1986); this is significantly lower than those found in previous decades. Homeless women are from 2 to 6 years younger (both mean and median) than homeless men (Multnomah County, Oregon, Department of Human Services, 1984; Robertson et al., 1985; Rossi et al., 1986). Reports from several cities indicate that the sheltered male population is younger still and that homeless women appear to be either very young or elderly. This is important because, unless they are disabled, the age of homeless adults in many parts of the country helps to determine their eligibility for entitlements, especially general assistance and Medicaid.

Homeless adults are likely never to have been married. Reported levels range from 40 percent in Portland, Oregon (Multnomah County, Oregon, Department of Human Services, 1984) to 64 percent in New York City (Hoffman et al., 1982). Homeless women are more likely than homeless men to have been married' In the Portland study, only 29 percent of homeless women had never married compared with 44 percent of homeless men. Never-married homeless adults are generally not members of households and often lack strong family ties. The absence of family ties removes the possibility of finding shelter with family members.

Minorities are overrepresented among homeless people in the nation's larger cities ( Table 1-2). This distribution reflects the overrepresentation of minorities in the poorest strata of American society (Morse, 1986).

The proportion of homeless people with a high school diploma has increased during the past 25 years. For example, in 1963, only 19 percent of homeless people in Chicago had completed high school (Bogue, 1963), compared with 35 percent of the general population of Chicago (U.S. Bureau of the Census, 1963). In 1985, 55 percent of the homeless population in that city were high school graduates (Rossi et al., 1986); the comparable figure for the entire population of Chicago was 56 percent, almost identical to that for the homeless population. While there was a greater divergence between the educational level of homeless and general populations in other cities (Roth et al., 1985; Farr et al., 1986), nationally the proportion of homeless adults with high school diplomas is approximately 45 percent.

Contrary to the fears expressed by public officials that their city may attract increasing numbers of homeless people if they do more to help, several recent studies indicate that the great majority of homeless people have been long-term residents of the city in which they are sheltered ( Table 1-3). This was confirmed during the site visits. It was also reported that when a city did attract transients, it was generally not by virtue of its entitlement programs but, rather, because of a favorable economic climate and the possibility of employment. People working directly with the homeless in various cities reported to the committee that transient persons failing to find employment in one city tended not to stay long and soon moved on in search of jobs.

Since the mean age of homeless men is approximately 35, it is not surprising that a large number are Vietnam veterans ( Table 1-4). Studies of homeless veterans in Los Angeles (Robertson, 1987) and Boston (Schutt, 1985) indicate that they are older than nonveterans, better educated, and more likely to have been married, factors that normally would indicate greater stability. They also tend to be white, although the percentage of ethnic minorities increases substantially among those who served in Vietnam.

As discussed in detail in Chapter 3, psychiatric problems and alcohol and drug abuse are common among homeless veterans. The Los Angeles and Boston studies both reported higher rates of psychiatric hospitalization than among nonveteran homeless people. The Boston study, as well as a study of homeless veterans in San Francisco (Swords to Plowshares, 1986), reported that veterans were more likely to identify substance abuse as a reason for homelessness. The San Francisco study reported that 45 percent suffered from alcohol abuse (19 percent reporting severe alcohol problems) and 23 percent from drug abuse.

The most recent statistics on homeless veterans come from the Homeless Chronically Mentally Ill outreach program conducted by the Veterans Administration as mandated by P.L. 100-6 (Rosenheck et al., 1987). The program is targeted specifically to mentally ill homeless veterans (and therefore does not present a valid sample of all homeless

veterans), but it is both the most recent research on homeless veterans and the most geographically comprehensive. The outreach effort was conducted in 26 states and included Veterans Administration medical centers serving rural, suburban, and urban areas. In its first 4 months of operation (May-September 1987) the program made contact with 6,342 homeless veterans.

Of the veterans contacted, 98.6 percent were men; 1.4 percent were women. The average age was 43:75 percent were either divorced or had never married. Sixty percent were white, 30 percent were black, and 9 percent were Hispanic. In regard to education, 82 percent were high school graduates. Thirty percent had served in combat, and 1.7 percent had been prisoners of war; 9 percent were diagnosed as having combat-related posttraumatic stress disorder. With regard to the time of their military duty, 38 percent were veterans of the Vietnam era, 21 percent served in the post-Vietnam period, and 18 percent served in the period between the Korean and Vietnam conflicts. Only 9 percent served in World War II and 10 percent in Korea.

Several authors have reported that between 5 and 10 percent of the homeless are employed full-time and between 10 and 20 percent are employed part-time or episodically (Brown et al., 1982, 1983; Multnomah County, Oregon, Department of Human Services, 1984, 1985; Rossi et al., 1986). These people frequently perform unskilled labor; are on the bottom rung of the economic ladder; and often lack job security, health insurance, and the skills necessary to succeed in a high-tech economy.

Many are homeless because their incomes have not kept pace with the dramatic increase in housing costs. The loss of a day or two of pay may make the difference between paying rent and being evicted.

Homeless Families

As mentioned previously, the fastest growing subgroup among the homeless population consists of families with children. In late 1986, the U.S. Conference of Mayors estimated that such families made up 28 percent of all homeless people in the 25 cities participating in the conference's annual survey of hunger, homelessness, and poverty in America. Most homeless families are headed by women with two or three children (Bassuk et al., 1986). Most of the children are under the age of 5 and are spending their critical developmental years without the stability and security of a permanent home (Towber, 1986a,b; Bassuk and Rubin, 1987; Wright and Weber, 1987).

The literature on the characteristics and needs of homeless families is largely anecdotal, although there are a few systematic studies describing the status and unmet needs of homeless families and the health status (Wright and Weber, 1987), emotional problems (Bassuk et al., 1986; Bassuk and Rubin, 1987; Bassuk and Gallagher, in press; Boxill and Beatty, in press), nutritional status (Acker et al., 1987), and problems in education and learning (Bassuk et al., 1986; Bassuk and Rubin, 1987) of homeless children. To date, the findings are generally descriptive, and there are large regional differences; only a few attempts have been made to generate and test hypotheses about the antecedents, course, and consequences of family homelessness by studying appropriate comparison groups. Despite limitations of the data base, reports of shelter providers, clinicians, agencies, advocates, and policymakers (Simpson et al., 1984; Gallagher, 1986), as well as the committee's site visits to sheltering facilities, tend to support the findings of existing studies. The combined information allows for some generalizations about the characteristics and needs of homeless families.

The vast majority of homeless families are headed by women, but the percentages vary by region. In western regions there are more intact homeless families than in eastern regions (Bassuk et al., 1986; Towber, 1986a,b; McChesney, 1986; Dumpson, 1987). Homeless families that include both parents appear to be more common in rural areas than in urban areas (see Appendix C). Because there is a lack of systematic information about the characteristics of intact homeless families, particularly the fathers, the following discussion concentrates primarily on mothers and children.

Homeless mothers tend to be in their late 20s (Bassuk et al., 1986; McChesney, 1986; Towber, 1986a,b; Dumpson, 1987), are either single or divorced, and have completed at least several years of high school (Bassuk et al., 1986; Towber, 1986a,b; Dumpson, 1987). Their ethnic status tends to mirror the ethnic composition of the area where they are living, with minorities overrepresented in the cities and whites predominating in suburban and rural areas (Bassuk et al., 1986). The vast majority of homeless families are recipients of Aid to Families with Dependent Children (AFDC). A Massachusetts study indicated that long-term AFDC users (those receiving benefits for longer than 2 years) are overrepresented among homeless families (Bassuk et al., 1986).

Researchers have reported that homeless mothers typically are quite isolated and have few, if any, supportive relationships. McChesney (1986) studied the support networks of homeless mothers with at least one child who were living in five Los Angeles County family shelters. She described their slide into homelessness as including ''. . . many varied and creative means to shelter themselves and their children" in an effort to stave off homelessness. Most striking was the fact that many families could not call on their own parents, brothers, or sisters as resources. There were three major reasons: "either their parents were dead, their parents and siblings didn't live in the Los Angeles area, or their parents and siblings were estranged" (McChesney, 1986). Bassuk and colleagues (1986), in their study of 80 homeless families living in family shelters in Massachusetts, also described fragmented support networks. When asked to name three persons on whom the mothers could depend during times of stress, 43 percent were unable to name anyone or could name only one person, and almost a quarter named their minor child as their principal source of emotional support (Bassuk et al., 1986). tn addition to economic and support system factors, serious health problems may also increase a family's risk of becoming homeless.

Many homeless mothers are victims of family violence, which suggests considerable overlap between families residing in family shelters and those residing in battered women's shelters (Ryback and Bassuk, 1986). Generally, a woman fleeing directly from an abusive mate turns to a battered women's shelter rather than to a family shelter. According to Bassuk et al. (1986), 45 percent of the women they interviewed in Massachusetts family shelters had a history of an abusive relationship with a spouse or mate, but this was generally not the immediate cause of their homelessness. In the only study reporting data about probable child abuse, Bassuk and coworkers found that 22 percent of homeless mothers were currently involved in an investigation or follow-up of child neglect or abuse (Bassuk et al., 1986; Bassuk and Rubin, 1987).

Many families had histories of residential instability and moved several times prior to their current shelter stay; most moved within the community where they were sheltered. A majority of families had been doubled up in overcrowded apartments with friends or relatives, while some had previously resided in other shelters or welfare hotels (Bassuk et al., 1986; Towber, 1986a,b).

A substantial proportion of homeless families using the sheltering system can be characterized as multiproblem families (Bassuk et al., 1986). These families have chronic economic, educational, vocational, and social problems; have fragmented support networks; and have difficulty accessing the traditional service delivery system; ". . . these families use a disproportionally large amount of social services and . . . traditional techniques of treating them fail or, at best, are only marginally successful . . ." (Kronenfeld et al., 1980). The multiproblem family typically seeks assistance when a crisis occurs, but ceases contact with the agency when the crisis abates (Gallagher, 1986).

Studies specifically describing the characteristics and needs of homeless children are quite sparse; studies seeking to provide an estimate of the number of homeless children nationwide are nonexistent. However, the magnitude of the problem can be seen in even the most conservative estimates: If there are approximately 735,000 people homeless on any given night (ICF Inc., 1987), and 25 percent of these people are members of intact families (U.S. Conference of Mayors, 1986), of whom 55 percent are children (Barbanel, 1985), then a minimum of 100,000 children are homeless on any given night of the year. This figure includes only children of intact families; it does not include runaway, throwaway, or abandoned children on the streets or in institutions.

Not surprisingly, researchers have reported erratic school attendance among homeless children. Shelters are frequently located far away from a school, and transportation may be lacking. Preliminary data reported by the Traveler's Aid Program and Child Welfare League (1987) indicate that of 163 families with 331 children in eight cities, only 57 percent of the homeless children attended school regularly. A study of 52 families residing in five New York City welfare hotels reported that, according to parents, 60 percent of their children missed less than 3 days of school per month, 30 percent missed between 4 and 10 days of school per month, and 10 percent missed more than 10 days a month, which is over half of the school days (Columbia University Masters of Public Administration Program, 1985).

Homeless Runaway and Throwaway Youths

the 1985 Greater Boston Adolescent Emergency Network (GBAEN) study (1985) of 84 adolescents using 11 shelters throughout Massachussetts;

the 1983 study of 118 adolescents in 7 shelters in New York City completed by David Shaffer and Carol L. M. Caton (1984); and

the 1984 study of 149 adolescents in a crisis center in Toronto, conducted by Mark-David Janus and colleagues (1987) and funded by the U.S. Department of Justice.

The amount of systematic data describing the characteristics of homeless adolescents is even scantier than those for other homeless subpopulations. In addition to its site visits, the committee reviewed three recent studies of runaway and throwaway youths:

Each study identified running away not so much as an event but as a process; adolescents leave home several times (each successive incident being of longer duration than the previous ones) before actually living on the streets. As Shaffer and Caton (1984) reported, "most adolescents start running away some years before they start to use shelters." With regard to throwaway youths, the Boston study found that 17 percent of subjects who had left home for the first time had been "evicted by their parents" (for the entire population in the Boston study, the proportion evicted, including those with multiple running away incidents, was 12 percent). The fundamental issue in trying to determine the extent of the throwaway youth population is to determine the line between a parent forcing a teenager out of the home and a parent creating a situation so intolerable that the youngster has no option but to leave. To quote Reverend Leonard A. Schneider, executive director of The Emergency Shelter in New York City:

It is just possible that running away may be an indication of a very healthy mind, and depression may be a very natural response to an intolerable situation. (Community Council of Greater New York, 1984)

Additional issues regarding the throwaway youth population are discussed in successive chapters: the dynamics of the running away process as it relates to homelessness ( Chapter 2); the health problems of runaway youths ( Chapter 3); and the current state of services for this population ( Chapter 5).

Homeless Elderly People

The percentage of elderly people among the homeless population is less than that among the general population. In all but one recently published study, the elderly made up less than 10 percent of the homeless population ( Table 1-5). The figure of 19.4 percent reported by Rossi et al. (1986) for the homeless in Chicago is the highest, but it is still low compared with the 29.6 percent elderly for that city's domiciled population. The contrast is even greater in Ohio, where 6.4 percent of the homeless were over age 60, in contrast to 21.7 percent of the population of the state as a whole (Roth et al., 1985). In the skid row area of Los Angeles, 5 percent of the homeless population is over age 61, in comparison with 17 percent domiciled elderly for the entire county (Farr et al., 1986). Nationwide, only 3 percent of the homeless people who presented themselves for care at the Johnson-Pew Health Care for the Homeless projects were over 65, even though 12 percent of the population of the United States is elderly (Wright and Weber, 1987).

Three hypotheses have been proposed to explain the small percentages of elderly homeless. The first suggests that on turning 65, many homeless people become eligible for various entitlements (Social Security, Medicare, senior citizen housing, etc.). It is possible that such programs generate enough income in benefits, lower housing costs, or both that people are able to leave the streets or at least are prevented from becoming homeless to begin with (Wright and Weber, 1987). The second possibility is that homeless people do not survive to old age, because the realities of a homeless existence are so severely debilitating (Wright and Weber, 1987). A 1956 study of men living on Chicago's skid row revealed an annual death rate of 70 per 1,000, in contrast to the national death rate for white men of 11 per 1,000 (Bogue, 1963). However, a third explanation for the small percentage of homeless elderly may be related to sampling. The subjects of most studies are self-selected and include residents of shelters, those who appear for medical treatment, people on the streets willing to be interviewed, and the like. The homeless elderly are particularly reluctant to use certain sheltering facilities that they view as dangerous (Coalition for the Homeless/Gray Panthers of New York City, 1984). To quote Joseph Doolin, the director of the Kit Clarke Senior House, which operates the Cardinal Medeiros Day Center for the homeless elderly of Boston, "younger homeless people tend to 'squeeze out' older street people [from the shelters]" (Doolin, 1986). To the extent that the homeless elderly do not participate in various programs for the homeless, they will be underrepresented in most studies.

The Rural Homeless

Since its first meeting, the committee has been concerned with the fact that almost all the scholarly literature describes the urban homeless. Only two studies, the statewide study of Ohio, Homelessness in Ohio: A Study of People in Need (Roth et al., 1985), and the statewide study of Vermont, Homelessness in Vermont (Vermont Department of Human Services, 1985), begin to address the physical and mental health problems of homeless people living in rural areas. As a result, the committee commissioned a special study of this population. Subsequently, the Health Resources and Services Administration of the U.S. Department of Health and Human Services, in cooperation with the committee, funded a more detailed analysis of this issue. This included site visits to rural areas in Alabama, Mississippi, Minnesota, and South Dakota. The results of this joint effort of the Institute of Medicine and the Department of Health and Human Services are included in Appendix C of this report.

Briefly, the problems of the rural homeless differ from those of their urban counterparts in several important ways. The rural homeless are far less visible than those in the cities; many live with relatives or others who are part of an extended family network. Some are officially domiciled because they pay a nominal token rent for the use of a shack or other substandard form of housing. However, they are even less likely than their urban counterparts to obtain assistance during times of economic or personal crisis. Rural areas do not have the range of social and financial supports available in most urban areas. Often, homeless people migrate to the cities in search of work; when they fail in that effort, they become a part of the growing numbers of homeless people in the cities. Those who stay in rural areas remain hidden until some event causes them to lose their housing, at which point they can be found living in, for example, cars, abandoned buildings, and woods. Even those communities with previously adequate social service systems are finding it increasingly difficult to serve the growing numbers of homeless people, especially in areas where the decline of agriculture, forestry, and mining is severe.

Summary

The homeless population is heterogeneous. While there is considerable controversy about the number of homeless people, there is general agreement that the number is becoming greater as each year passes. As the number increases, so do the complexities of the homelessness problem:

Why do people become homeless? Which interventions can be used to prevent or resolve the state of homelessness? What strategies must be developed to address the long-term issues involved with this problem?

As has been seen in this chapter, there are several subgroups among the general population of homeless people: individual adults, families with children, adolescents and young adults, the elderly, and people in rural areas. While together they all share one common problem-the lack of a stable residence-they each have specific needs.

As will be seen in the next chapter, the long-established system that has traditionally addressed homelessness now finds itself confronted with a seemingly overwhelming set of problems.

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Brown, C. E., R. Paredes, and L. Stark. 1982. The Homeless of Phoenix: A Profile. Phoenix, Ariz.: Phoenix South Community Mental Health Center.

Brown, C. E., S. MacFarlane, R. Paredes, and L. Stark. 1983. The Homeless of Phoenix: Who Are They and What Should Be Done? Phoenix, Ariz.: Phoenix South Community Mental Health Center.

Clark, A. L. 1985. Health care needs of homeless women in Baltimore. Seminar paper submitted to the faculty of the graduate school of the University of Maryland, College Park, in partial fulfillment of the requirements for the master of science degree.

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Crystal, S. M., M. Goldstein, and R. Levitt. 1982. Chronic and Situational Dependency: Long-Term Residents in a Shelter for Men. New York: Human Resources Administration of the City of New York.

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Dumpson, J. R. 1987. A Shelter Is Not a Home. Report of the Manhattan Borough President's Task Force on Housing for Homeless Families. New York: Manhattan Borough President's Task Force on Housing for Homeless Families.

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Fischer, P. J., and W. R. Breakey. 1986. Characteristics of the Homeless with Alcohol Problems in Baltimore: Some Preliminary Results. Baltimore: Department of Health Policy and Management, School of Hygiene and Public Health, and Department of Psychiatry and Behavioral Sciences, School of Medicine, The Johns Hopkins University.

Fischer, P. J., W. R. Breakey, S. Shapiro, J. C. Anthony, and M. Kramer. 1986. Mental health and social characteristics of the homeless: A survey of mission users. American Journal of Public Health 76(5):519-524. [ PMC free article: PMC1646617 ] [ PubMed: 3963280 ]

Freeman, R. B., and B. Hall. 1986. Permanent Homelessness in America? Working paper no. 2013. Cambridge, Mass.: National Bureau of Economic Research.

Gallagher, E. 1986. No Place Like Home: A Report on the Tragedy of Homeless Children and Their Families in Massachusetts. Boston: Massachusetts Committee for Children and Youth, Inc.

Greater Boston Adolescent Emergency Network. 1985. Ride a Painted Pony on a Spinning Wheel Ride. Boston: Massachusetts Committee for Children and Youth, Inc.

Hombs, M. E., and M. Snyder. 1982. Homelessness in America: Forced March to Nowhere. Washington, D.C.: Community for Creative Non-Violence.

Janus, M.-D., A. McCormack, A. W. Burgess, and C. Hartman. 1987. Adolescent Runaways: Causes and Consequences. Lexington, Mass.: D.C. Heath, Lexington Books.

Kronenfeld, D., M. Phillips, and V. Middleton-Jeter. 1980. The forgotten ones: Treatment of single parent multi-problem families in a residential setting. Prepared under Grant no. 18-P-90705/03. Washington, D.C.: U.S. Department of Health and Human Services, Office of Human Development Services.

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Morse, G. A., N. M. Shields, C. R. Hanneke, R. J. Calsyn, G. K. Burger, and B. Nelson. 1985. Homeless People in St. Louis: A Mental Health Program Evaluation, Field Study and Followup Investigation. Jefferson City, Mo.: State Department of Mental Health.

Mowbray, C. V., S. Johnson, A. Solarn, and C. J. Combs. 1985. Mental Health and Homelessness in Detroit: A Research Study. Lansing: Michigan Department of Mental Health.

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Multnomah County, Oregon, Department of Human Services. 1985. Homeless Women. Multnomah County, Oreg.: Social Services Division, Department of Human Services.

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Rosenheck, R., P. Gallup, C. Leda, P. Leaf, R. Milstein, I. Voynick, P. Errera, L. Lehman. G. Koerber, and R. Murphy. 1987. Progress Report on the Veterans Administration Program for Homeless Chronically Mentally Ill Veterans. Washington, D.C.: Veterans Administration.

Rossi, P. H., G. A. Fisher, and G. Willis. 1986. The Condition of the Homeless in Chicago. A report prepared by the Social and Demographic Research Institute, University of Massachusetts at Amherst, and the National Opinion Research Center, University of Chicago.

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Schutt, R. K. 1985. Boston's Homeless: Their Backgrounds, Problems, and Needs. Boston: University of Massachusetts.

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References

1

''Throwaway" youths refers to children and adolescents who are evicted from their homes by their parents or another adult in a position of responsibility for them.

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There have always been homeless people in the United States. As economic circumstances and demographic forces have fluctuated, so have the size and composition of the homeless population, although relatively permanent skid rows where homeless people congregate have long been a feature of many large cities.

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Changes in surface air temperature over the past 50 years.[1] The Arctic has warmed the most, and temperatures on land have generally increased more than sea surface temperatures.

Earth's average surface air temperature has increased almost 1.5°C (about2.5 °F) since the Industrial Revolution. Natural forces cause some variability, but the 20-year average shows the progressive influence of human activity.[2]

In common usage, climate change describes global warming-the ongoing increase in global average temperature-and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is primarily caused by humans burning fossil fuels since the Industrial Revolution. Fossil fuel use, deforestation, and some agricultural and industrial practices add to greenhouse gases. These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary greenhouse gas driving global warming, has grown by about 50% and is at levels unseen for millions of years.

Climate change has an increasingly large impact on the environment. Deserts are expanding, while heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost, retreat of glaciers and sea ice decline. Higher temperatures are also causing more intense storms, droughts, and other weather extremes. Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct. Even if efforts to minimise future warming are successful, some effects will continue for centuries. These include ocean heating, ocean acidification and sea level rise.

Climate change threatens people with increased flooding, extreme heat, increased food and water scarcity, more disease, and economic loss. Human migration and conflict can also be a result. The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for a small share of global emissions, yet have the least ability to adapt and are most vulnerable to climate change.

Many climate change impacts have been felt in recent years, with 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.7 °C (4.9 °F) by the end of the century. Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.

Fossil fuel use can be phased out by conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind, solar, hydro, and nuclear power. Cleanly generated electricity can replace fossil fuels for powering transportation, heating buildings, and running industrial processes. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and farming with methods that capture carbon in soil.

Terminology

Before the 1980s it was unclear whether the warming effect of increased greenhouse gases was stronger than the cooling effect of airborne particulates in air pollution. Scientists used the term inadvertent climate modification to refer to human impacts on the climate at this time. In the 1980s, the terms global warming and climate change became more common, often being used interchangeably. Scientifically, global warming refers only to increased surface warming, while climate change describes both global warming and its effects on Earth's climate system, such as precipitation changes.

Climate change can also be used more broadly to include changes to the climate that have happened throughout Earth's history. Global warming-used as early as 1975-became the more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate. Since the 2000s, climate change has increased usage. Various scientists, politicians and media now use the terms climate crisis or climate emergency to talk about climate change, and global heating instead of global warming.

Global temperature rise

Global surface temperature reconstruction over the last 2000 years using proxy data from tree rings, corals, and ice cores in blue.[36] Directly observed data is in red.[37]

Temperature records prior to global warming

Over the last few million years human beings evolved in a climate that cycled through ice ages, with global average temperature ranging between 1 °C warmer and 5-6 °C colder than current levels. One of the hotter periods was the Last Interglacial between 115,000 and 130,000 years ago, when sea levels were 6 to 9 meters higher than today. The most recent glacial maximum 20,000 years ago had sea levels that were about 125 meters (410 ft) lower than today.

Temperatures stabilized in the current interglacial period beginning 11,700 years ago. Historical patterns of warming and cooling, like the Medieval Warm Period and the Little Ice Age, did not occur at the same time across different regions. Temperatures may have reached as high as those of the late 20th century in a limited set of regions. Climate information for that period comes from climate proxies, such as trees and ice cores.

Warming since the Industrial Revolution

There has been an increase in ocean heat content during recent decades as the oceans absorb over 90% of the heat from global warming.[46]

Around 1850 thermometer records began to provide global coverage. Between the 18th century and 1970 there was little net warming, as the warming impact of greenhouse gas emissions was offset by cooling from sulfur dioxide emissions. Sulfur dioxide causes acid rain, but it also produces sulfate aerosols in the atmosphere, which reflect sunlight and cause so-called global dimming. After 1970, the increasing accumulation of greenhouse gases and controls on sulfur pollution led to a marked increase in temperature.

Ongoing changes in climate have had no precedent for several thousand years. Multiple independent datasets all show worldwide increases in surface temperature, at a rate of around 0.2 °C per decade. The 2013-2022 decade warmed to an average 1.15 °C [1.00-1.25 °C] compared to the pre-industrial baseline (1850-1900). Not every single year was warmer than the last: internal climate variability processes can make any year 0.2 °C warmer or colder than the average. From 1998 to 2013, negative phases of two such processes, Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) caused a so-called " global warming hiatus". After the hiatus, the opposite occurred, with years like 2023 exhibiting temperatures well above even the recent average. This is why the temperature change is defined in terms of a 20-year average, which reduces the noise of hot and cold years and decadal climate patterns, and detects the long-term signal.

A wide range of other observations reinforce the evidence of warming. The upper atmosphere is cooling, because greenhouse gases are trapping heat near the Earth's surface, and so less heat is radiating into space. Warming reduces average snow cover and forces the retreat of glaciers. At the same time, warming also causes greater evaporation from the oceans, leading to more atmospheric humidity, more and heavier precipitation. Plants are flowering earlier in spring, and thousands of animal species have been permanently moving to cooler areas.

Differences by region

Different regions of the world warm at different rates. The pattern is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global average surface temperature. This is because oceans lose more heat by evaporation and oceans can store a lot of heat. The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean. The rest has heated the atmosphere, melted ice, and warmed the continents.

The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat. Local black carbon deposits on snow and ice also contribute to Arctic warming. Arctic surface temperatures are increasing between three and four times faster than in the rest of the world. Melting of ice sheets near the poles weakens both the Atlantic and the Antarctic limb of thermohaline circulation, which further changes the distribution of heat and precipitation around the globe.

Future global temperatures

CMIP6 multi-model projections of global surface temperature changes for the year 2090 relative to the 1850-1900 average. The current trajectory for warming by the end of the century is roughly halfway between these two extremes.[22][81][82]

The World Meteorological Organization estimates a 66% chance of global temperatures exceeding 1.5 °C warming from the preindustrial baseline for at least one year between 2023 and 2027. Because the IPCC uses a 20-year average to define global temperature changes, a single year exceeding 1.5 °C does not break the limit.

The IPCC expects the 20-year average global temperature to exceed +1.5 °C in the early 2030s. The IPCC Sixth Assessment Report (2023) included projections that by 2100 global warming is very likely to reach 1.0-1.8 °C under a scenario with very low emissions of greenhouse gases, 2.1-3.5 °C under an intermediate emissions scenario, or 3.3-5.7 °C under a very high emissions scenario. In the intermediate and high emission scenarios, the warming will continue past 2100.

The remaining carbon budget for staying beneath certain temperature increases is determined by modelling the carbon cycle and climate sensitivity to greenhouse gases. According to the IPCC, global warming can be kept below 1.5 °C with a two-thirds chance if emissions after 2018 do not exceed 420 or 570 gigatonnes of CO ₂. This corresponds to 10 to 13 years of current emissions. There are high uncertainties about the budget. For instance, it may be 100 gigatonnes of CO ₂ equivalent smaller due to CO ₂ and methane release from permafrost and wetlands. However, it is clear that fossil fuel resources need to be proactively kept in the ground to prevent substantial warming. Otherwise, their shortages would not occur until the emissions have already locked in significant long-term impacts.

Causes of recent global temperature rise

Drivers of climate change from 1850-1900 to 2010-2019. There was no significant contribution from internal variability or solar and volcanic drivers.

The climate system experiences various cycles on its own which can last for years, decades or even centuries. For example, El Niño events cause short-term spikes in surface temperature while La Niña events cause short term cooling. Their relative frequency can affect global temperature trends on a decadal timescale. Other changes are caused by an imbalance of energy from external forcings. Examples of these include changes in the concentrations of greenhouse gases, solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun.

To determine the human contribution to climate change, unique "fingerprints" for all potential causes are developed and compared with both observed patterns and known internal climate variability. For example, solar forcing-whose fingerprint involves warming the entire atmosphere-is ruled out because only the lower atmosphere has warmed. Atmospheric aerosols produce a smaller, cooling effect. Other drivers, such as changes in albedo, are less impactful.

Greenhouse gases

CO₂ concentrations over the last 800,000 years as measured from ice cores[99][100][101][102] (blue/green) and directly[103] (black)

Greenhouse gases are transparent to sunlight, and thus allow it to pass through the atmosphere to heat the Earth's surface. The Earth radiates it as heat, and greenhouse gases absorb a portion of it. This absorption slows the rate at which heat escapes into space, trapping heat near the Earth's surface and warming it over time.

While water vapour (≈50%) and clouds (≈25%) are the biggest contributors to the greenhouse effect, they primarily change as a function of temperature and are therefore mostly considered to be feedbacks that change climate sensitivity. On the other hand, concentrations of gases such as CO ₂ (≈20%), tropospheric ozone, CFCs and nitrous oxide are added or removed independently from temperature, and are therefore considered to be external forcings that change global temperatures.

Before the Industrial Revolution, naturally-occurring amounts of greenhouse gases caused the air near the surface to be about 33 °C warmer than it would have been in their absence. Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels ( coal, oil, and natural gas), has increased the amount of greenhouse gases in the atmosphere, resulting in a radiative imbalance. In 2019, the concentrations of CO₂ and methane had increased by about 48% and 160%, respectively, since 1750. These CO ₂ levels are higher than they have been at any time during the last 2 million years. Concentrations of methane are far higher than they were over the last 800,000 years.

The Global Carbon Project shows how additions to CO₂ since 1880 have been caused by different sources ramping up one after another.

Global anthropogenic greenhouse gas emissions in 2019 were equivalent to 59 billion tonnes of CO ₂. Of these emissions, 75% was CO ₂, 18% was methane, 4% was nitrous oxide, and 2% was fluorinated gases. CO ₂ emissions primarily come from burning fossil fuels to provide energy for transport, manufacturing, heating, and electricity. Additional CO ₂ emissions come from deforestation and industrial processes, which include the CO ₂ released by the chemical reactions for making cement, steel, aluminum, and fertiliser. Methane emissions come from livestock, manure, rice cultivation, landfills, wastewater, and coal mining, as well as oil and gas extraction. Nitrous oxide emissions largely come from the microbial decomposition of fertiliser.

While methane only lasts in the atmosphere for an average of 12 years, CO ₂ lasts much longer. The Earth's surface absorbs CO2 as part of the carbon cycle. While plants on land and in the ocean absorb most excess emissions of CO ₂ every year, that CO ₂ is returned to the atmosphere when biological matter is digested, burns, or decays. Land-surface carbon sink processes, such as carbon fixation in the soil and photosynthesis, remove about 29% of annual global CO ₂ emissions. The ocean has absorbed 20 to 30% of emitted CO ₂ over the last 2 decades. CO ₂ is only removed from the atmosphere for the long term when it is stored in the Earth's crust, which is a process that can take millions of years to complete.

Land surface changes

According to Food and Agriculture Organization, around 30% of Earth's land area is largely unusable for humans ( glaciers, deserts, etc.), 26% is forests, 10% is shrubland and 34% is agricultural land. Deforestation is the main land use change contributor to global warming, as the destroyed trees release CO ₂, and are not replaced by new trees, removing that carbon sink. Between 2001 and 2018, 27% of deforestation was from permanent clearing to enable agricultural expansion for crops and livestock. Another 24% has been lost to temporary clearing under the shifting cultivation agricultural systems. 26% was due to logging for wood and derived products, and wildfires have accounted for the remaining 23%. Some forests have not been fully cleared, but were already degraded by these impacts. Restoring these forests also recovers their potential as a carbon sink.

Local vegetation cover impacts how much of the sunlight gets reflected back into space ( albedo), and how much heat is lost by evaporation. For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also modify the release of chemical compounds that influence clouds, and by changing wind patterns. In tropic and temperate areas the net effect is to produce significant warming, and forest restoration can make local temperatures cooler. At latitudes closer to the poles, there is a cooling effect as forest is replaced by snow-covered (and more reflective) plains. Globally, these increases in surface albedo have been the dominant direct influence on temperature from land use change. Thus, land use change to date is estimated to have a slight cooling effect.

Other factors

Aerosols and clouds

Air pollution, in the form of aerosols, affects the climate on a large scale. Aerosols scatter and absorb solar radiation. From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed. This phenomenon is popularly known as global dimming, and is primarily attributed to sulfate aerosols produced by the combustion of fossil fuels with heavy sulfur concentrations like coal and bunker fuel. Smaller contributions come from black carbon, organic carbon from combustion of fossil fuels and biofuels, and from anthropogenic dust. Globally, aerosols have been declining since 1990 due to pollution controls, meaning that they no longer mask greenhouse gas warming as much.

Aerosols also have indirect effects on the Earth's energy budget. Sulfate aerosols act as cloud condensation nuclei and lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets. They also reduce the growth of raindrops, which makes clouds more reflective to incoming sunlight. Indirect effects of aerosols are the largest uncertainty in radiative forcing.

While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase the absorption of sunlight, it also increases melting and sea-level rise. Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050. The effect of decreasing sulfur content of fuel oil for ships since 2020 is estimated to cause an additional 0.05 °C increase in global mean temperature by 2050.

Solar and volcanic activity

The Fourth National Climate Assessment ("NCA4", USGCRP, 2017) includes charts illustrating that neither solar nor volcanic activity can explain the observed warming.[141][142]

As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect the climate system. Solar irradiance has been measured directly by satellites, and indirect measurements are available from the early 1600s onwards. Since 1880, there has been no upward trend in the amount of the Sun's energy reaching the Earth, in contrast to the warming of the lower atmosphere (the troposphere). The upper atmosphere (the stratosphere) would also be warming if the Sun was sending more energy to Earth, but instead, it has been cooling. This is consistent with greenhouse gases preventing heat from leaving the Earth's atmosphere.

Explosive volcanic eruptions can release gases, dust and ash that partially block sunlight and reduce temperatures, or they can send water vapor into the atmosphere, which adds to greenhouse gases and increases temperatures. These impacts on temperature only last for several years, because both water vapor and volcanic material have low persistence in the atmosphere. volcanic CO₂ emissions are more persistent, but they are equivalent to less than 1% of current human-caused CO ₂ emissions. Volcanic activity still represents the single largest natural impact (forcing) on temperature in the industrial era. Yet, like the other natural forcings, it has had negligible impacts on global temperature trends since the Industrial Revolution.

Climate change feedbacks

Sea ice reflects 50% to 70% of incoming sunlight, while the ocean, being darker, reflects only 6%. As an area of sea ice melts and exposes more ocean, more heat is absorbed by the ocean, raising temperatures that melt still more ice. This is a positive feedback process.[149]

The response of the climate system to an initial forcing is modified by feedbacks: increased by "self-reinforcing" or "positive" feedbacks and reduced by "balancing" or "negative" feedbacks. The main reinforcing feedbacks are the water-vapour feedback, the ice-albedo feedback, and the net effect of clouds. The primary balancing mechanism is radiative cooling, as Earth's surface gives off more heat to space in response to rising temperature. In addition to temperature feedbacks, there are feedbacks in the carbon cycle, such as the fertilising effect of CO ₂ on plant growth. Feedbacks are expected to trend in a positive direction as greenhouse gas emissions continue, raising climate sensitivty.

Radiative feedbacks are physical processes that influence the rate of global warming in response to warming. For instance, warmer air can hold more moisture, and water vapour itself is a potent greenhouse gas. Warmer air can also result in clouds becoming higher and thinner, where they act as an insulator and warm the planet. Another major feedback is the reduction of snow cover and sea ice in the Arctic, reducing the reflectivity of the Earth's surface there and contributing to amplification of Arctic temperature changes. Arctic amplification is also thawing permafrost, which releases methane and CO ₂ into the atmosphere.

Around half of human-caused CO ₂ emissions have been absorbed by land plants and by the oceans. This fraction is not static and if future CO ₂ emissions decrease, the Earth will be able to absorb up to around 70%. If they increase substantially, it'll still absorb more carbon than now, but the overall fraction will decrease to below 40%. This is because climate change increases droughts and heat waves that eventually inhibit plant growth on land, and soils will release more carbon from dead plants when they are warmer. The rate at which oceans absorb atmospheric carbon will be lowered as they become more acidic and experience changes in thermohaline circulation and phytoplankton distribution. Uncertainty over feedbacks, particularly cloud cover, is the major reason why different climate models project different magnitudes of warming for a given amount of emissions.

Energy flows between space, the atmosphere, and Earth's surface. Most sunlight passes through the atmosphere to heat the Earth's surface, then greenhouse gases absorb most of the heat the Earth radiates in response. Adding to greenhouse gases increases this insulating effect, causing an energy imbalance that heats the planet up.

A climate model is a representation of the physical, chemical and biological processes that affect the climate system. Models include natural processes like changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing. Models are used to estimate the degree of warming future emissions will cause when accounting for the strength of climate feedbacks. Models also predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere.

The physical realism of models is tested by examining their ability to simulate contemporary or past climates. Past models have underestimated the rate of Arctic shrinkage and underestimated the rate of precipitation increase. Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations. The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes". Additionally, climate models may be unable to adequately predict short-term regional climatic shifts.

A subset of climate models add societal factors to a physical climate model. These models simulate how population, economic growth, and energy use affect-and interact with-the physical climate. With this information, these models can produce scenarios of future greenhouse gas emissions. This is then used as input for physical climate models and carbon cycle models to predict how atmospheric concentrations of greenhouse gases might change. Depending on the socioeconomic scenario and the mitigation scenario, models produce atmospheric CO ₂ concentrations that range widely between 380 and 1400 ppm.

The sixth IPCC Assessment Report projects changes in average soil moisture at 2.0 °C of warming, as measured in standard deviations from the 1850 to 1900 baseline.

Environmental effects

The environmental effects of climate change are broad and far-reaching, affecting oceans, ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations. Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency. Extremely wet or dry events within the monsoon period have increased in India and East Asia. Monsoonal precipitation over the Northern Hemisphere has increased since 1980. The rainfall rate and intensity of hurricanes and typhoons is likely increasing, and the geographic range likely expanding poleward in response to climate warming. Frequency of tropical cyclones has not increased as a result of climate change.

Global sea level is rising as a consequence of thermal expansion and the melting of glaciers and ice sheets. Between 1993 and 2020, the rise increased over time, averaging 3.3 ± 0.3 mm per year. Over the 21st century, the IPCC projects 32-62 cm of sea level rise under a low emission scenario, 44-76 cm under an intermediate one and 65-101 cm under a very high emission scenario. Marine ice sheet instability processes in Antarctica may add substantially to these values, including the possibility of a 2-meter sea level rise by 2100 under high emissions.

Climate change has led to decades of shrinking and thinning of the Arctic sea ice. While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur once every three to ten years at a warming level of 2 °C. Higher atmospheric CO ₂ concentrations cause more CO ₂ to dissolve in the oceans, which is making them more acidic. Because oxygen is less soluble in warmer water, its concentrations in the ocean are decreasing, and dead zones are expanding.

Tipping points and long-term impacts

Different levels of global warming may cause different parts of Earth's climate system to reach tipping points that cause transitions to different states.[199][200]

Greater degrees of global warming increase the risk of passing through ' tipping points'-thresholds beyond which certain major impacts can no longer be avoided even if temperatures return to their previous state. For instance, the Greenland ice sheet is already melting, but if global warming reaches levels between 1.7 °C and 2.3 °C, its melting will continue until it fully disappears. If the warming is later reduced to 1.5 °C or less, it will still lose a lot more ice than if the warming was never allowed to reach the threshold in the first place. While the ice sheets would melt over millennia, other tipping points would occur faster and give societies less time to respond. The collapse of major ocean currents like the Atlantic meridional overturning circulation (AMOC), and irreversible damage to key ecosystems like the Amazon rainforest and coral reefs can unfold in a matter of decades.

The long-term effects of climate change on oceans include further ice melt, ocean warming, sea level rise, ocean acidification and ocean deoxygenation. The timescale of long-term impacts are centuries to millennia due to CO ₂'s long atmospheric lifetime. When net emissions stabilise surface air temperatures will also stabilise, but oceans and ice caps will continue to absorb excess heat from the atmosphere. The result is an estimated total sea level rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years. Oceanic CO ₂ uptake is slow enough that ocean acidification will also continue for hundreds to thousands of years. Deep oceans (below 2,000 metres (6,600 ft)) are also already committed to losing over 10% of their dissolved oxygen by the warming which occurred to date. Further, the West Antarctic ice sheet appears committed to practically irreversible melting, which would increase the sea levels by at least 3.3 m (10 ft 10 in) over approximately 2000 years.

Nature and wildlife

Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes. For instance, the range of hundreds of North American birds has shifted northward at an average rate of 1.5 km/year over the past 55 years. Higher atmospheric CO ₂ levels and an extended growing season have resulted in global greening. However, heatwaves and drought have reduced ecosystem productivity in some regions. The future balance of these opposing effects is unclear. A related phenomenon driven by climate change is woody plant encroachment, affecting up to 500 million hectares globally. Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics. The size and speed of global warming is making abrupt changes in ecosystems more likely. Overall, it is expected that climate change will result in the extinction of many species.

The oceans have heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles faster than species on land. Just as on land, heat waves in the ocean occur more frequently due to climate change, harming a wide range of organisms such as corals, kelp, and seabirds. Ocean acidification makes it harder for marine calcifying organisms such as mussels, barnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs. Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life. Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts. Plants have come under increased stress from damage by insects.

The effects of climate change are impacting humans everywhere in the world. Impacts can be observed on all continents and ocean regions, with low-latitude, less developed areas facing the greatest risk. Continued warming has potentially "severe, pervasive and irreversible impacts" for people and ecosystems. The risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries.

Food and health

The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century. Extreme weather leads to injury and loss of life. Various infectious diseases are more easily transmitted in a warmer climate, such as dengue fever and malaria. Crop failures can lead to food shortages and malnutrition, particularly effecting children. Both children and older people are vulnerable to extreme heat. The WHO has estimated that between 2030 and 2050, climate change would cause around 250,000 additional deaths per year. They assessed deaths from heat exposure in elderly people, increases in diarrhea, malaria, dengue, coastal flooding, and childhood malnutrition. By 2100, 50% to 75% of the global population may face climate conditions that are life-threatening due to combined effects of extreme heat and humidity.

Climate change is affecting food security. It has caused reduction in global yields of maize, wheat, and soybeans between 1981 and 2010. Future warming could further reduce global yields of major crops. Crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative. Up to an additional 183 million people worldwide, particularly those with lower incomes, are at risk of hunger as a consequence of these impacts. Climate change also impacts fish populations. Globally, less will be available to be fished. Regions dependent on glacier water, regions that are already dry, and small islands have a higher risk of water stress due to climate change.

Livelihoods and inequality

Economic damages due to climate change may be severe and there is a chance of disastrous consequences. Severe impacts are expected in South-East Asia and sub-Saharan Africa, where most of the local inhabitants are dependent upon natural and agricultural resources. Heat stress can prevent outdoor labourers from working. If warming reaches 4 °C then labour capacity in those regions could be reduced by 30 to 50%. The World Bank estimates that between 2016 and 2030, climate change could drive over 120 million people into extreme poverty without adaptation.

Inequalities based on wealth and social status have worsened due to climate change. Major difficulties in mitigating, adapting to, and recovering from climate shocks are faced by marginalised people who have less control over resources. Indigenous people, who are subsistent on their land and ecosystems, will face endangerment to their wellness and lifestyles due to climate change. An expert elicitation concluded that the role of climate change in armed conflict has been small compared to factors such as socio-economic inequality and state capabilities.

While women are not inherently more at risk from climate change and shocks, limits on women's resources and discriminatory gender norms constrain their adaptive capacity and resilience. For example, women's work burdens, including hours worked in agriculture, tend to decline less than men's during climate shocks such as heat stress.

Climate migration

Low-lying islands and coastal communities are threatened by sea level rise, which makes urban flooding more common. Sometimes, land is permanently lost to the sea. This could lead to statelessness for people in island nations, such as the Maldives and Tuvalu. In some regions, the rise in temperature and humidity may be too severe for humans to adapt to. With worst-case climate change, models project that almost one-third of humanity might live in Sahara-like uninhabitable and extremely hot climates.

These factors can drive climate or environmental migration, within and between countries. More people are expected to be displaced because of sea level rise, extreme weather and conflict from increased competition over natural resources. Climate change may also increase vulnerability, leading to "trapped populations" who are not able to move due to a lack of resources.

Reducing and recapturing emissions

Global greenhouse gas emission scenarios, based on policies and pledges as of November 2021

Climate change can be mitigated by reducing the rate at which greenhouse gases are emitted into the atmosphere, and by increasing the rate at which carbon dioxide is removed from the atmosphere. In order to limit global warming to less than 1.5 °C global greenhouse gas emissions needs to be net-zero by 2050, or by 2070 with a 2 °C target. This requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry.

The United Nations Environment Programme estimates that countries need to triple their pledges under the Paris Agreement within the next decade to limit global warming to 2 °C. An even greater level of reduction is required to meet the 1.5 °C goal. With pledges made under the Paris Agreement as of October 2021, global warming would still have a 66% chance of reaching about 2.7 °C (range: 2.2-3.2 °C) by the end of the century. Globally, limiting warming to 2 °C may result in higher economic benefits than economic costs.

Although there is no single pathway to limit global warming to 1.5 or 2 °C, most scenarios and strategies see a major increase in the use of renewable energy in combination with increased energy efficiency measures to generate the needed greenhouse gas reductions. To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry, such as preventing deforestation and restoring natural ecosystems by reforestation.

Other approaches to mitigating climate change have a higher level of risk. Scenarios that limit global warming to 1.5 °C typically project the large-scale use of carbon dioxide removal methods over the 21st century. There are concerns, though, about over-reliance on these technologies, and environmental impacts. Solar radiation modification (SRM) is also a possible supplement to deep reductions in emissions. However, SRM raises significant ethical and legal concerns, and the risks are imperfectly understood.

Clean energy

Coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing.[278]

Wind and solar power, Germany

Renewable energy is key to limiting climate change. For decades, fossil fuels have accounted for roughly 80% of the world's energy use. The remaining share has been split between nuclear power and renewables (including hydropower, bioenergy, wind and solar power and geothermal energy). Fossil fuel use is expected to peak in absolute terms prior to 2030 and then to decline, with coal use experiencing the sharpest reductions. Renewables represented 75% of all new electricity generation installed in 2019, nearly all solar and wind. Other forms of clean energy, such as nuclear and hydropower, currently have a larger share of the energy supply. However, their future growth forecasts appear limited in comparison.

While solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations, green energy policies are needed to achieve a rapid transition from fossil fuels to renewables. To achieve carbon neutrality by 2050, renewable energy would become the dominant form of electricity generation, rising to 85% or more by 2050 in some scenarios. Investment in coal would be eliminated and coal use nearly phased out by 2050.

Electricity generated from renewable sources would also need to become the main energy source for heating and transport. Transport can switch away from internal combustion engine vehicles and towards electric vehicles, public transit, and active transport (cycling and walking). For shipping and flying, low-carbon fuels would reduce emissions. Heating could be increasingly decarbonised with technologies like heat pumps.

There are obstacles to the continued rapid growth of clean energy, including renewables. For wind and solar, there are environmental and land use concerns for new projects. Wind and solar also produce energy intermittently and with seasonal variability. Traditionally, hydro dams with reservoirs and conventional power plants have been used when variable energy production is low. Going forward, battery storage can be expanded, energy demand and supply can be matched, and long-distance transmission can smooth variability of renewable outputs. Bioenergy is often not carbon-neutral and may have negative consequences for food security. The growth of nuclear power is constrained by controversy around radioactive waste, nuclear weapon proliferation, and accidents. Hydropower growth is limited by the fact that the best sites have been developed, and new projects are confronting increased social and environmental concerns.

Low-carbon energy improves human health by minimising climate change as well as reducing air pollution deaths, which were estimated at 7 million annually in 2016. Meeting the Paris Agreement goals that limit warming to a 2 °C increase could save about a million of those lives per year by 2050, whereas limiting global warming to 1.5 °C could save millions and simultaneously increase energy security and reduce poverty. Improving air quality also has economic benefits which may be larger than mitigation costs.

Energy conservation

Reducing energy demand is another major aspect of reducing emissions. If less energy is needed, there is more flexibility for clean energy development. It also makes it easier to manage the electricity grid, and minimises carbon-intensive infrastructure development. Major increases in energy efficiency investment will be required to achieve climate goals, comparable to the level of investment in renewable energy. Several COVID-19 related changes in energy use patterns, energy efficiency investments, and funding have made forecasts for this decade more difficult and uncertain.

Strategies to reduce energy demand vary by sector. In the transport sector, passengers and freight can switch to more efficient travel modes, such as buses and trains, or use electric vehicles. Industrial strategies to reduce energy demand include improving heating systems and motors, designing less energy-intensive products, and increasing product lifetimes. In the building sector the focus is on better design of new buildings, and higher levels of energy efficiency in retrofitting. The use of technologies like heat pumps can also increase building energy efficiency.

Agriculture and industry

Taking into account direct and indirect emissions, industry is the sector with the highest share of global emissions. Data as of 2019 from the IPCC.

Agriculture and forestry face a triple challenge of limiting greenhouse gas emissions, preventing the further conversion of forests to agricultural land, and meeting increases in world food demand. A set of actions could reduce agriculture and forestry-based emissions by two thirds from 2010 levels. These include reducing growth in demand for food and other agricultural products, increasing land productivity, protecting and restoring forests, and reducing greenhouse gas emissions from agricultural production.

On the demand side, a key component of reducing emissions is shifting people towards plant-based diets. Eliminating the production of livestock for meat and dairy would eliminate about 3/4ths of all emissions from agriculture and other land use. Livestock also occupy 37% of ice-free land area on Earth and consume feed from the 12% of land area used for crops, driving deforestation and land degradation.

Steel and cement production are responsible for about 13% of industrial CO ₂ emissions. In these industries, carbon-intensive materials such as coke and lime play an integral role in the production, so that reducing CO ₂ emissions requires research into alternative chemistries.

Carbon sequestration

Most CO₂ emissions have been absorbed by carbon sinks, including plant growth, soil uptake, and ocean uptake (2020 Global Carbon Budget).

Natural carbon sinks can be enhanced to sequester significantly larger amounts of CO ₂ beyond naturally occurring levels. Reforestation and afforestation (planting forests where there were none before) are among the most mature sequestration techniques, although the latter raises food security concerns. Farmers can promote sequestration of carbon in soils through practices such as use of winter cover crops, reducing the intensity and frequency of tillage, and using compost and manure as soil amendments. Forest and landscape restoration yields many benefits for the climate, including greenhouse gas emissions sequestration and reduction. Restoration/recreation of coastal wetlands, prairie plots and seagrass meadows increases the uptake of carbon into organic matter. When carbon is sequestered in soils and in organic matter such as trees, there is a risk of the carbon being re-released into the atmosphere later through changes in land use, fire, or other changes in ecosystems.

Where energy production or CO ₂-intensive heavy industries continue to produce waste CO ₂, the gas can be captured and stored instead of released to the atmosphere. Although its current use is limited in scale and expensive, carbon capture and storage (CCS) may be able to play a significant role in limiting CO ₂ emissions by mid-century. This technique, in combination with bioenergy ( BECCS) can result in net negative emissions as CO ₂ is drawn from the atmosphere. It remains highly uncertain whether carbon dioxide removal techniques will be able to play a large role in limiting warming to 1.5 °C. Policy decisions that rely on carbon dioxide removal increase the risk of global warming rising beyond international goals.

Adaptation

Adaptation is "the process of adjustment to current or expected changes in climate and its effects". Without additional mitigation, adaptation cannot avert the risk of "severe, widespread and irreversible" impacts. More severe climate change requires more transformative adaptation, which can be prohibitively expensive. The capacity and potential for humans to adapt is unevenly distributed across different regions and populations, and developing countries generally have less. The first two decades of the 21st century saw an increase in adaptive capacity in most low- and middle-income countries with improved access to basic sanitation and electricity, but progress is slow. Many countries have implemented adaptation policies. However, there is a considerable gap between necessary and available finance.

Adaptation to sea level rise consists of avoiding at-risk areas, learning to live with increased flooding, and building flood controls. If that fails, managed retreat may be needed. There are economic barriers for tackling dangerous heat impact. Avoiding strenuous work or having air conditioning is not possible for everybody. In agriculture, adaptation options include a switch to more sustainable diets, diversification, erosion control, and genetic improvements for increased tolerance to a changing climate. Insurance allows for risk-sharing, but is often difficult to get for people on lower incomes. Education, migration and early warning systems can reduce climate vulnerability. Planting mangroves or encouraging other coastal vegetation can buffer storms.

Ecosystems adapt to climate change, a process that can be supported by human intervention. By increasing connectivity between ecosystems, species can migrate to more favourable climate conditions. Species can also be introduced to areas acquiring a favorable climate. Protection and restoration of natural and semi-natural areas helps build resilience, making it easier for ecosystems to adapt. Many of the actions that promote adaptation in ecosystems, also help humans adapt via ecosystem-based adaptation. For instance, restoration of natural fire regimes makes catastrophic fires less likely, and reduces human exposure. Giving rivers more space allows for more water storage in the natural system, reducing flood risk. Restored forest acts as a carbon sink, but planting trees in unsuitable regions can exacerbate climate impacts.

There are synergies but also trade-offs between adaptation and mitigation. An example for synergy is increased food productivity, which has large benefits for both adaptation and mitigation. An example of a trade-off is that increased use of air conditioning allows people to better cope with heat, but increases energy demand. Another trade-off example is that more compact urban development may reduce emissions from transport and construction, but may also increase the urban heat island effect, exposing people to heat-related health risks.

Policies and politics

The Climate Change Performance Index ranks countries by greenhouse gas emissions (40% of score), renewable energy (20%), energy use (20%), and climate policy (20%).

Countries that are most vulnerable to climate change have typically been responsible for a small share of global emissions. This raises questions about justice and fairness. Limiting global warming makes it much easier to achieve the UN's Sustainable Development Goals, such as eradicating poverty and reducing inequalities. The connection is recognised in Sustainable Development Goal 13 which is to "take urgent action to combat climate change and its impacts". The goals on food, clean water and ecosystem protection have synergies with climate mitigation.

The geopolitics of climate change is complex. It has often been framed as a free-rider problem, in which all countries benefit from mitigation done by other countries, but individual countries would lose from switching to a low-carbon economy themselves. Sometimes mitigation also has localised benefits though. For instance, the benefits of a coal phase-out to public health and local environments exceed the costs in almost all regions. Furthermore, net importers of fossil fuels win economically from switching to clean energy, causing net exporters to face stranded assets: fossil fuels they cannot sell.

Policy options

A wide range of policies, regulations, and laws are being used to reduce emissions. As of 2019, carbon pricing covers about 20% of global greenhouse gas emissions. Carbon can be priced with carbon taxes and emissions trading systems. Direct global fossil fuel subsidies reached $319 billion in 2017, and $5.2 trillion when indirect costs such as air pollution are priced in. Ending these can cause a 28% reduction in global carbon emissions and a 46% reduction in air pollution deaths. Money saved on fossil subsidies could be used to support the transition to clean energy instead. More direct methods to reduce greenhouse gases include vehicle efficiency standards, renewable fuel standards, and air pollution regulations on heavy industry. Several countries require utilities to increase the share of renewables in power production.

Climate justice

Policy designed through the lens of climate justice tries to address human rights issues and social inequality. According to proponents of climate justice, the costs of climate adaptation should be paid by those most responsible for climate change, while the beneficiaries of payments should be those suffering impacts. One way this can be addressed in practice is to have wealthy nations pay poorer countries to adapt.

Oxfam found that in 2023 the wealthiest 10% of people were responsible for 50% of global emissions, while the bottom 50% were responsible for just 8%. Production of emissions is another way to look at responsibility: under that approach, the top 21 fossil fuel companies would owe cumulative climate reparations of $5.4 trillion over the period 2025-2050. To achieve a just transition, people working in the fossil fuel sector would also need other jobs, and their communities would need investments.

International climate agreements

Since 2000, rising CO₂ emissions in China and the rest of world have surpassed the output of the United States and Europe.[358]

Per person, the United States generates CO₂ at a far faster rate than other primary regions.[358]

Nearly all countries in the world are parties to the 1994 United Nations Framework Convention on Climate Change (UNFCCC). The goal of the UNFCCC is to prevent dangerous human interference with the climate system. As stated in the convention, this requires that greenhouse gas concentrations are stabilised in the atmosphere at a level where ecosystems can adapt naturally to climate change, food production is not threatened, and economic development can be sustained. The UNFCCC does not itself restrict emissions but rather provides a framework for protocols that do. Global emissions have risen since the UNFCCC was signed. Its yearly conferences are the stage of global negotiations.

The 1997 Kyoto Protocol extended the UNFCCC and included legally binding commitments for most developed countries to limit their emissions. During the negotiations, the G77 (representing developing countries) pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions, since developed countries contributed most to the accumulation of greenhouse gases in the atmosphere. Per-capita emissions were also still relatively low in developing countries and developing countries would need to emit more to meet their development needs.

The 2009 Copenhagen Accord has been widely portrayed as disappointing because of its low goals, and was rejected by poorer nations including the G77. Associated parties aimed to limit the global temperature rise to below 2 °C. The Accord set the goal of sending $100 billion per year to developing countries for mitigation and adaptation by 2020, and proposed the founding of the Green Climate Fund. As of 2020, only 83.3 billion were delivered. Only in 2023 the target is expected to be achieved.

In 2015 all UN countries negotiated the Paris Agreement, which aims to keep global warming well below 2.0 °C and contains an aspirational goal of keeping warming under 1.5 °C. The agreement replaced the Kyoto Protocol. Unlike Kyoto, no binding emission targets were set in the Paris Agreement. Instead, a set of procedures was made binding. Countries have to regularly set ever more ambitious goals and reevaluate these goals every five years. The Paris Agreement restated that developing countries must be financially supported. As of October 2021, 194 states and the European Union have signed the treaty and 191 states and the EU have ratified or acceded to the agreement.

The 1987 Montreal Protocol, an international agreement to stop emitting ozone-depleting gases, may have been more effective at curbing greenhouse gas emissions than the Kyoto Protocol specifically designed to do so. The 2016 Kigali Amendment to the Montreal Protocol aims to reduce the emissions of hydrofluorocarbons, a group of powerful greenhouse gases which served as a replacement for banned ozone-depleting gases. This made the Montreal Protocol a stronger agreement against climate change.

National responses

In 2019, the United Kingdom parliament became the first national government to declare a climate emergency. Other countries and jurisdictions followed suit. That same year, the European Parliament declared a "climate and environmental emergency". The European Commission presented its European Green Deal with the goal of making the EU carbon-neutral by 2050. In 2021, the European Commission released its " Fit for 55" legislation package, which contains guidelines for the car industry; all new cars on the European market must be zero-emission vehicles from 2035.

Major countries in Asia have made similar pledges: South Korea and Japan have committed to become carbon-neutral by 2050, and China by 2060. While India has strong incentives for renewables, it also plans a significant expansion of coal in the country. Vietnam is among very few coal-dependent, fast-developing countries that pledged to phase out unabated coal power by the 2040s or as soon as possible thereafter.

As of 2021, based on information from 48 national climate plans, which represent 40% of the parties to the Paris Agreement, estimated total greenhouse gas emissions will be 0.5% lower compared to 2010 levels, below the 45% or 25% reduction goals to limit global warming to 1.5 °C or 2 °C, respectively.

Denial and misinformation

Data has been cherry picked from short periods to falsely assert that global temperatures are not rising. Blue trendlines show short periods that mask longer-term warming trends (red trendlines). Blue rectangle with blue dots shows the so-called global warming hiatus.

Public debate about climate change has been strongly affected by climate change denial and misinformation, which originated in the United States and has since spread to other countries, particularly Canada and Australia. Climate change denial has originated from fossil fuel companies, industry groups, conservative think tanks, and contrarian scientists. Like the tobacco industry, the main strategy of these groups has been to manufacture doubt about climate-change related scientific data and results. People who hold unwarranted doubt about climate change are called climate change "skeptics", although "contrarians" or "deniers" are more appropriate terms.

There are different variants of climate denial: some deny that warming takes place at all, some acknowledge warming but attribute it to natural influences, and some minimise the negative impacts of climate change. Manufacturing uncertainty about the science later developed into a manufactured controversy: creating the belief that there is significant uncertainty about climate change within the scientific community in order to delay policy changes. Strategies to promote these ideas include criticism of scientific institutions, and questioning the motives of individual scientists. An echo chamber of climate-denying blogs and media has further fomented misunderstanding of climate change.

Public awareness and opinion

The public substantially underestimates the degree of scientific consensus that humans are causing climate change.[394] Studies from 2019 to 2021[395][4][396] found scientific consensus to range from 98.7 to 100%.

Climate change came to international public attention in the late 1980s. Due to media coverage in the early 1990s, people often confused climate change with other environmental issues like ozone depletion. In popular culture, the climate fiction movie The Day After Tomorrow (2004) and the Al Gore documentary An Inconvenient Truth (2006) focused on climate change.

Significant regional, gender, age and political differences exist in both public concern for, and understanding of, climate change. More highly educated people, and in some countries, women and younger people, were more likely to see climate change as a serious threat. Partisan gaps also exist in many countries, and countries with high CO ₂ emissions tend to be less concerned. Views on causes of climate change vary widely between countries. Concern has increased over time, to the point where in 2021 a majority of citizens in many countries express a high level of worry about climate change, or view it as a global emergency. Higher levels of worry are associated with stronger public support for policies that address climate change.

Climate movement

Climate protests demand that political leaders take action to prevent climate change. They can take the form of public demonstrations, fossil fuel divestment, lawsuits and other activities. Prominent demonstrations include the School Strike for Climate. In this initiative, young people across the globe have been protesting since 2018 by skipping school on Fridays, inspired by Swedish teenager Greta Thunberg. Mass civil disobedience actions by groups like Extinction Rebellion have protested by disrupting roads and public transport.

Litigation is increasingly used as a tool to strengthen climate action from public institutions and companies. Activists also initiate lawsuits which target governments and demand that they take ambitious action or enforce existing laws on climate change. Lawsuits against fossil-fuel companies generally seek compensation for loss and damage.

Early discoveries

Scientists in the 19th century such as Alexander von Humboldt began to foresee the effects of climate change. In the 1820s, Joseph Fourier proposed the greenhouse effect to explain why Earth's temperature was higher than the Sun's energy alone could explain. Earth's atmosphere is transparent to sunlight, so sunlight reaches the surface where it is converted to heat. However, the atmosphere is not transparent to heat radiating from the surface, and captures some of that heat, which in turn warms the planet.

In 1856 Eunice Newton Foote demonstrated that the warming effect of the Sun is greater for air with water vapour than for dry air, and that the effect is even greater with carbon dioxide (CO ₂). She concluded that "An atmosphere of that gas would give to our earth a high temperature..."

Studying what would become known as the greenhouse effect, Tyndall's pre-1861 ratio spectrophotometer measured how much various gases in a tube absorb and emit infrared radiation-which humans experience as heat.

Starting in 1859, John Tyndall established that nitrogen and oxygen-together totaling 99% of dry air-are transparent to radiated heat. However, water vapour and gases such as methane and carbon dioxide absorb radiated heat and re-radiate that heat into the atmosphere. Tyndall proposed that changes in the concentrations of these gases may have caused climatic changes in the past, including ice ages.

Svante Arrhenius noted that water vapour in air continuously varied, but the CO ₂ concentration in air was influenced by long-term geological processes. Warming from increased CO ₂ levels would increase the amount of water vapour, amplifying warming in a positive feedback loop. In 1896, he published the first climate model of its kind, projecting that halving CO ₂ levels could have produced a drop in temperature initiating an ice age. Arrhenius calculated the temperature increase expected from doubling CO ₂ to be around 5-6 °C. Other scientists were initially skeptical and believed that the greenhouse effect was saturated so that adding more CO ₂ would make no difference, and that the climate would be self-regulating. Beginning in 1938, Guy Stewart Callendar published evidence that climate was warming and CO ₂ levels were rising, but his calculations met the same objections.

Development of a scientific consensus

Scientific consensus on causation: Academic studies of scientific agreement on human-caused global warming among climate experts (2010-2015) reflect that the level of consensus correlates with expertise in climate science.[423] A 2019 study found scientific consensus to be at 100%,[424] and a 2021 study concluded that consensus exceeded 99%.[425] Another 2021 study found that 98.7% of climate experts indicated that the Earth is getting warmer mostly because of human activity.[426]

In the 1950s, Gilbert Plass created a detailed computer model that included different atmospheric layers and the infrared spectrum. This model predicted that increasing CO ₂ levels would cause warming. Around the same time, Hans Suess found evidence that CO ₂ levels had been rising, and Roger Revelle showed that the oceans would not absorb the increase. The two scientists subsequently helped Charles Keeling to begin a record of continued increase, which has been termed the " Keeling Curve". Scientists alerted the public, and the dangers were highlighted at James Hansen's 1988 Congressional testimony. The Intergovernmental Panel on Climate Change (IPCC), set up in 1988 to provide formal advice to the world's governments, spurred interdisciplinary research. As part of the IPCC reports, scientists assess the scientific discussion that takes place in peer-reviewed journal articles.

There is a near-complete scientific consensus that the climate is warming and that this is caused by human activities. As of 2019, agreement in recent literature reached over 99%. No scientific body of national or international standing disagrees with this view. Consensus has further developed that some form of action should be taken to protect people against the impacts of climate change. National science academies have called on world leaders to cut global emissions. The 2021 IPCC Assessment Report stated that it is "unequivocal" that climate change is caused by humans.

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IPCC reports

Fourth Assessment Report

Fifth Assessment report

IPCC (2014). Field, C. B.; Barros, V. R.; Dokken, D. J.; Mach, K. J.; et al. (eds.). Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. ISBN 978-1-107-05807-1.. Chapters 1-20, SPM, and Technical Summary.

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IPCC (2014). Edenhofer, O.; Pichs-Madruga, R.; Sokona, Y.; Farahani, E.; et al. (eds.). Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK & New York, NY: Cambridge University Press. ISBN 978-1-107-05821-7.

IPCC AR5 SYR (2014). The Core Writing Team; Pachauri, R. K.; Meyer, L. A. (eds.). Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Geneva, Switzerland: IPCC.

Special Report: Global Warming of 1.5 °C

Special Report: Climate change and Land

Special Report: The Ocean and Cryosphere in a Changing Climate

Sixth Assessment Report

IPCC (2021). Masson-Delmotte, V.; Zhai, P.; Pirani, A.; Connors, S. L.; et al. (eds.). Climate Change 2021: The Physical Science Basis (PDF). Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, US: Cambridge University Press (In Press).

IPCC (2022). Pörtner, H.-O.; Roberts, D.C.; Tignor, M.; Poloczanska, E.S.; Mintenbeck, K.; Alegría, A.; Craig, M.; Langsdorf, S.; Löschke, S.; Möller, V.; Okem, A.; Rama, B.; et al. (eds.). Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.

IPCC (2022). Shukla, P.R.; Skea, J.; Slade, R.; Al Khourdajie, A.; et al. (eds.). Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, NY, USA: Cambridge University Press. doi:10.1017/9781009157926. ISBN 978-1-009-15792-6.

IPCC (2023). Core Writing Team; Lee, H.; Romero, J.; et al. (eds.). IPCC, 2023: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, H. Lee and J. Romero (Eds.)]. IPCC, Geneva, Switzerland (PDF). Geneva, Switzerland: IPCC. doi:10.59327/IPCC/AR6-9789291691647. hdl:1885/299630. ISBN 978-92-9169-164-7. S2CID 260074696.

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In common usage, climate change describes global warming-the ongoing increase in global average temperature-and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is primarily caused by humans burning fossil fuels since the Industrial Revolution.

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Protest expert Aldon Morris explains how social justice movements succeed

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Changes in surface air temperature over the past 50 years.[1] The Arctic has warmed the most, and temperatures on land have generally increased more than sea surface temperatures.

Earth's average surface air temperature has increased almost 1.5°C (about2.5 °F) since the Industrial Revolution. Natural forces cause some variability, but the 20-year average shows the progressive influence of human activity.[2]

In common usage, climate change describes global warming-the ongoing increase in global average temperature-and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is primarily caused by humans burning fossil fuels since the Industrial Revolution. Fossil fuel use, deforestation, and some agricultural and industrial practices add to greenhouse gases. These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary greenhouse gas driving global warming, has grown by about 50% and is at levels unseen for millions of years.

Climate change has an increasingly large impact on the environment. Deserts are expanding, while heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost, retreat of glaciers and sea ice decline. Higher temperatures are also causing more intense storms, droughts, and other weather extremes. Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct. Even if efforts to minimise future warming are successful, some effects will continue for centuries. These include ocean heating, ocean acidification and sea level rise.

Climate change threatens people with increased flooding, extreme heat, increased food and water scarcity, more disease, and economic loss. Human migration and conflict can also be a result. The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for a small share of global emissions, yet have the least ability to adapt and are most vulnerable to climate change.

Many climate change impacts have been felt in recent years, with 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.7 °C (4.9 °F) by the end of the century. Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.

Fossil fuel use can be phased out by conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind, solar, hydro, and nuclear power. Cleanly generated electricity can replace fossil fuels for powering transportation, heating buildings, and running industrial processes. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and farming with methods that capture carbon in soil.

Terminology

Before the 1980s it was unclear whether the warming effect of increased greenhouse gases was stronger than the cooling effect of airborne particulates in air pollution. Scientists used the term inadvertent climate modification to refer to human impacts on the climate at this time. In the 1980s, the terms global warming and climate change became more common, often being used interchangeably. Scientifically, global warming refers only to increased surface warming, while climate change describes both global warming and its effects on Earth's climate system, such as precipitation changes.

Climate change can also be used more broadly to include changes to the climate that have happened throughout Earth's history. Global warming-used as early as 1975-became the more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate. Since the 2000s, climate change has increased usage. Various scientists, politicians and media now use the terms climate crisis or climate emergency to talk about climate change, and global heating instead of global warming.

Global temperature rise

Global surface temperature reconstruction over the last 2000 years using proxy data from tree rings, corals, and ice cores in blue.[36] Directly observed data is in red.[37]

Temperature records prior to global warming

Over the last few million years human beings evolved in a climate that cycled through ice ages, with global average temperature ranging between 1 °C warmer and 5-6 °C colder than current levels. One of the hotter periods was the Last Interglacial between 115,000 and 130,000 years ago, when sea levels were 6 to 9 meters higher than today. The most recent glacial maximum 20,000 years ago had sea levels that were about 125 meters (410 ft) lower than today.

Temperatures stabilized in the current interglacial period beginning 11,700 years ago. Historical patterns of warming and cooling, like the Medieval Warm Period and the Little Ice Age, did not occur at the same time across different regions. Temperatures may have reached as high as those of the late 20th century in a limited set of regions. Climate information for that period comes from climate proxies, such as trees and ice cores.

Warming since the Industrial Revolution

There has been an increase in ocean heat content during recent decades as the oceans absorb over 90% of the heat from global warming.[46]

Around 1850 thermometer records began to provide global coverage. Between the 18th century and 1970 there was little net warming, as the warming impact of greenhouse gas emissions was offset by cooling from sulfur dioxide emissions. Sulfur dioxide causes acid rain, but it also produces sulfate aerosols in the atmosphere, which reflect sunlight and cause so-called global dimming. After 1970, the increasing accumulation of greenhouse gases and controls on sulfur pollution led to a marked increase in temperature.

Ongoing changes in climate have had no precedent for several thousand years. Multiple independent datasets all show worldwide increases in surface temperature, at a rate of around 0.2 °C per decade. The 2013-2022 decade warmed to an average 1.15 °C [1.00-1.25 °C] compared to the pre-industrial baseline (1850-1900). Not every single year was warmer than the last: internal climate variability processes can make any year 0.2 °C warmer or colder than the average. From 1998 to 2013, negative phases of two such processes, Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) caused a so-called " global warming hiatus". After the hiatus, the opposite occurred, with years like 2023 exhibiting temperatures well above even the recent average. This is why the temperature change is defined in terms of a 20-year average, which reduces the noise of hot and cold years and decadal climate patterns, and detects the long-term signal.

A wide range of other observations reinforce the evidence of warming. The upper atmosphere is cooling, because greenhouse gases are trapping heat near the Earth's surface, and so less heat is radiating into space. Warming reduces average snow cover and forces the retreat of glaciers. At the same time, warming also causes greater evaporation from the oceans, leading to more atmospheric humidity, more and heavier precipitation. Plants are flowering earlier in spring, and thousands of animal species have been permanently moving to cooler areas.

Differences by region

Different regions of the world warm at different rates. The pattern is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global average surface temperature. This is because oceans lose more heat by evaporation and oceans can store a lot of heat. The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean. The rest has heated the atmosphere, melted ice, and warmed the continents.

The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat. Local black carbon deposits on snow and ice also contribute to Arctic warming. Arctic surface temperatures are increasing between three and four times faster than in the rest of the world. Melting of ice sheets near the poles weakens both the Atlantic and the Antarctic limb of thermohaline circulation, which further changes the distribution of heat and precipitation around the globe.

Future global temperatures

CMIP6 multi-model projections of global surface temperature changes for the year 2090 relative to the 1850-1900 average. The current trajectory for warming by the end of the century is roughly halfway between these two extremes.[22][81][82]

The World Meteorological Organization estimates a 66% chance of global temperatures exceeding 1.5 °C warming from the preindustrial baseline for at least one year between 2023 and 2027. Because the IPCC uses a 20-year average to define global temperature changes, a single year exceeding 1.5 °C does not break the limit.

The IPCC expects the 20-year average global temperature to exceed +1.5 °C in the early 2030s. The IPCC Sixth Assessment Report (2023) included projections that by 2100 global warming is very likely to reach 1.0-1.8 °C under a scenario with very low emissions of greenhouse gases, 2.1-3.5 °C under an intermediate emissions scenario, or 3.3-5.7 °C under a very high emissions scenario. In the intermediate and high emission scenarios, the warming will continue past 2100.

The remaining carbon budget for staying beneath certain temperature increases is determined by modelling the carbon cycle and climate sensitivity to greenhouse gases. According to the IPCC, global warming can be kept below 1.5 °C with a two-thirds chance if emissions after 2018 do not exceed 420 or 570 gigatonnes of CO ₂. This corresponds to 10 to 13 years of current emissions. There are high uncertainties about the budget. For instance, it may be 100 gigatonnes of CO ₂ equivalent smaller due to CO ₂ and methane release from permafrost and wetlands. However, it is clear that fossil fuel resources need to be proactively kept in the ground to prevent substantial warming. Otherwise, their shortages would not occur until the emissions have already locked in significant long-term impacts.

Causes of recent global temperature rise

Drivers of climate change from 1850-1900 to 2010-2019. There was no significant contribution from internal variability or solar and volcanic drivers.

The climate system experiences various cycles on its own which can last for years, decades or even centuries. For example, El Niño events cause short-term spikes in surface temperature while La Niña events cause short term cooling. Their relative frequency can affect global temperature trends on a decadal timescale. Other changes are caused by an imbalance of energy from external forcings. Examples of these include changes in the concentrations of greenhouse gases, solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun.

To determine the human contribution to climate change, unique "fingerprints" for all potential causes are developed and compared with both observed patterns and known internal climate variability. For example, solar forcing-whose fingerprint involves warming the entire atmosphere-is ruled out because only the lower atmosphere has warmed. Atmospheric aerosols produce a smaller, cooling effect. Other drivers, such as changes in albedo, are less impactful.

Greenhouse gases

CO₂ concentrations over the last 800,000 years as measured from ice cores[99][100][101][102] (blue/green) and directly[103] (black)

Greenhouse gases are transparent to sunlight, and thus allow it to pass through the atmosphere to heat the Earth's surface. The Earth radiates it as heat, and greenhouse gases absorb a portion of it. This absorption slows the rate at which heat escapes into space, trapping heat near the Earth's surface and warming it over time.

While water vapour (≈50%) and clouds (≈25%) are the biggest contributors to the greenhouse effect, they primarily change as a function of temperature and are therefore mostly considered to be feedbacks that change climate sensitivity. On the other hand, concentrations of gases such as CO ₂ (≈20%), tropospheric ozone, CFCs and nitrous oxide are added or removed independently from temperature, and are therefore considered to be external forcings that change global temperatures.

Before the Industrial Revolution, naturally-occurring amounts of greenhouse gases caused the air near the surface to be about 33 °C warmer than it would have been in their absence. Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels ( coal, oil, and natural gas), has increased the amount of greenhouse gases in the atmosphere, resulting in a radiative imbalance. In 2019, the concentrations of CO₂ and methane had increased by about 48% and 160%, respectively, since 1750. These CO ₂ levels are higher than they have been at any time during the last 2 million years. Concentrations of methane are far higher than they were over the last 800,000 years.

The Global Carbon Project shows how additions to CO₂ since 1880 have been caused by different sources ramping up one after another.

Global anthropogenic greenhouse gas emissions in 2019 were equivalent to 59 billion tonnes of CO ₂. Of these emissions, 75% was CO ₂, 18% was methane, 4% was nitrous oxide, and 2% was fluorinated gases. CO ₂ emissions primarily come from burning fossil fuels to provide energy for transport, manufacturing, heating, and electricity. Additional CO ₂ emissions come from deforestation and industrial processes, which include the CO ₂ released by the chemical reactions for making cement, steel, aluminum, and fertiliser. Methane emissions come from livestock, manure, rice cultivation, landfills, wastewater, and coal mining, as well as oil and gas extraction. Nitrous oxide emissions largely come from the microbial decomposition of fertiliser.

While methane only lasts in the atmosphere for an average of 12 years, CO ₂ lasts much longer. The Earth's surface absorbs CO2 as part of the carbon cycle. While plants on land and in the ocean absorb most excess emissions of CO ₂ every year, that CO ₂ is returned to the atmosphere when biological matter is digested, burns, or decays. Land-surface carbon sink processes, such as carbon fixation in the soil and photosynthesis, remove about 29% of annual global CO ₂ emissions. The ocean has absorbed 20 to 30% of emitted CO ₂ over the last 2 decades. CO ₂ is only removed from the atmosphere for the long term when it is stored in the Earth's crust, which is a process that can take millions of years to complete.

Land surface changes

According to Food and Agriculture Organization, around 30% of Earth's land area is largely unusable for humans ( glaciers, deserts, etc.), 26% is forests, 10% is shrubland and 34% is agricultural land. Deforestation is the main land use change contributor to global warming, as the destroyed trees release CO ₂, and are not replaced by new trees, removing that carbon sink. Between 2001 and 2018, 27% of deforestation was from permanent clearing to enable agricultural expansion for crops and livestock. Another 24% has been lost to temporary clearing under the shifting cultivation agricultural systems. 26% was due to logging for wood and derived products, and wildfires have accounted for the remaining 23%. Some forests have not been fully cleared, but were already degraded by these impacts. Restoring these forests also recovers their potential as a carbon sink.

Local vegetation cover impacts how much of the sunlight gets reflected back into space ( albedo), and how much heat is lost by evaporation. For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also modify the release of chemical compounds that influence clouds, and by changing wind patterns. In tropic and temperate areas the net effect is to produce significant warming, and forest restoration can make local temperatures cooler. At latitudes closer to the poles, there is a cooling effect as forest is replaced by snow-covered (and more reflective) plains. Globally, these increases in surface albedo have been the dominant direct influence on temperature from land use change. Thus, land use change to date is estimated to have a slight cooling effect.

Other factors

Aerosols and clouds

Air pollution, in the form of aerosols, affects the climate on a large scale. Aerosols scatter and absorb solar radiation. From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed. This phenomenon is popularly known as global dimming, and is primarily attributed to sulfate aerosols produced by the combustion of fossil fuels with heavy sulfur concentrations like coal and bunker fuel. Smaller contributions come from black carbon, organic carbon from combustion of fossil fuels and biofuels, and from anthropogenic dust. Globally, aerosols have been declining since 1990 due to pollution controls, meaning that they no longer mask greenhouse gas warming as much.

Aerosols also have indirect effects on the Earth's energy budget. Sulfate aerosols act as cloud condensation nuclei and lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets. They also reduce the growth of raindrops, which makes clouds more reflective to incoming sunlight. Indirect effects of aerosols are the largest uncertainty in radiative forcing.

While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase the absorption of sunlight, it also increases melting and sea-level rise. Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050. The effect of decreasing sulfur content of fuel oil for ships since 2020 is estimated to cause an additional 0.05 °C increase in global mean temperature by 2050.

Solar and volcanic activity

The Fourth National Climate Assessment ("NCA4", USGCRP, 2017) includes charts illustrating that neither solar nor volcanic activity can explain the observed warming.[141][142]

As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect the climate system. Solar irradiance has been measured directly by satellites, and indirect measurements are available from the early 1600s onwards. Since 1880, there has been no upward trend in the amount of the Sun's energy reaching the Earth, in contrast to the warming of the lower atmosphere (the troposphere). The upper atmosphere (the stratosphere) would also be warming if the Sun was sending more energy to Earth, but instead, it has been cooling. This is consistent with greenhouse gases preventing heat from leaving the Earth's atmosphere.

Explosive volcanic eruptions can release gases, dust and ash that partially block sunlight and reduce temperatures, or they can send water vapor into the atmosphere, which adds to greenhouse gases and increases temperatures. These impacts on temperature only last for several years, because both water vapor and volcanic material have low persistence in the atmosphere. volcanic CO₂ emissions are more persistent, but they are equivalent to less than 1% of current human-caused CO ₂ emissions. Volcanic activity still represents the single largest natural impact (forcing) on temperature in the industrial era. Yet, like the other natural forcings, it has had negligible impacts on global temperature trends since the Industrial Revolution.

Climate change feedbacks

Sea ice reflects 50% to 70% of incoming sunlight, while the ocean, being darker, reflects only 6%. As an area of sea ice melts and exposes more ocean, more heat is absorbed by the ocean, raising temperatures that melt still more ice. This is a positive feedback process.[149]

The response of the climate system to an initial forcing is modified by feedbacks: increased by "self-reinforcing" or "positive" feedbacks and reduced by "balancing" or "negative" feedbacks. The main reinforcing feedbacks are the water-vapour feedback, the ice-albedo feedback, and the net effect of clouds. The primary balancing mechanism is radiative cooling, as Earth's surface gives off more heat to space in response to rising temperature. In addition to temperature feedbacks, there are feedbacks in the carbon cycle, such as the fertilising effect of CO ₂ on plant growth. Feedbacks are expected to trend in a positive direction as greenhouse gas emissions continue, raising climate sensitivty.

Radiative feedbacks are physical processes that influence the rate of global warming in response to warming. For instance, warmer air can hold more moisture, and water vapour itself is a potent greenhouse gas. Warmer air can also result in clouds becoming higher and thinner, where they act as an insulator and warm the planet. Another major feedback is the reduction of snow cover and sea ice in the Arctic, reducing the reflectivity of the Earth's surface there and contributing to amplification of Arctic temperature changes. Arctic amplification is also thawing permafrost, which releases methane and CO ₂ into the atmosphere.

Around half of human-caused CO ₂ emissions have been absorbed by land plants and by the oceans. This fraction is not static and if future CO ₂ emissions decrease, the Earth will be able to absorb up to around 70%. If they increase substantially, it'll still absorb more carbon than now, but the overall fraction will decrease to below 40%. This is because climate change increases droughts and heat waves that eventually inhibit plant growth on land, and soils will release more carbon from dead plants when they are warmer. The rate at which oceans absorb atmospheric carbon will be lowered as they become more acidic and experience changes in thermohaline circulation and phytoplankton distribution. Uncertainty over feedbacks, particularly cloud cover, is the major reason why different climate models project different magnitudes of warming for a given amount of emissions.

Energy flows between space, the atmosphere, and Earth's surface. Most sunlight passes through the atmosphere to heat the Earth's surface, then greenhouse gases absorb most of the heat the Earth radiates in response. Adding to greenhouse gases increases this insulating effect, causing an energy imbalance that heats the planet up.

A climate model is a representation of the physical, chemical and biological processes that affect the climate system. Models include natural processes like changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing. Models are used to estimate the degree of warming future emissions will cause when accounting for the strength of climate feedbacks. Models also predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere.

The physical realism of models is tested by examining their ability to simulate contemporary or past climates. Past models have underestimated the rate of Arctic shrinkage and underestimated the rate of precipitation increase. Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations. The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes". Additionally, climate models may be unable to adequately predict short-term regional climatic shifts.

A subset of climate models add societal factors to a physical climate model. These models simulate how population, economic growth, and energy use affect-and interact with-the physical climate. With this information, these models can produce scenarios of future greenhouse gas emissions. This is then used as input for physical climate models and carbon cycle models to predict how atmospheric concentrations of greenhouse gases might change. Depending on the socioeconomic scenario and the mitigation scenario, models produce atmospheric CO ₂ concentrations that range widely between 380 and 1400 ppm.

The sixth IPCC Assessment Report projects changes in average soil moisture at 2.0 °C of warming, as measured in standard deviations from the 1850 to 1900 baseline.

Environmental effects

The environmental effects of climate change are broad and far-reaching, affecting oceans, ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations. Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency. Extremely wet or dry events within the monsoon period have increased in India and East Asia. Monsoonal precipitation over the Northern Hemisphere has increased since 1980. The rainfall rate and intensity of hurricanes and typhoons is likely increasing, and the geographic range likely expanding poleward in response to climate warming. Frequency of tropical cyclones has not increased as a result of climate change.

Global sea level is rising as a consequence of thermal expansion and the melting of glaciers and ice sheets. Between 1993 and 2020, the rise increased over time, averaging 3.3 ± 0.3 mm per year. Over the 21st century, the IPCC projects 32-62 cm of sea level rise under a low emission scenario, 44-76 cm under an intermediate one and 65-101 cm under a very high emission scenario. Marine ice sheet instability processes in Antarctica may add substantially to these values, including the possibility of a 2-meter sea level rise by 2100 under high emissions.

Climate change has led to decades of shrinking and thinning of the Arctic sea ice. While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur once every three to ten years at a warming level of 2 °C. Higher atmospheric CO ₂ concentrations cause more CO ₂ to dissolve in the oceans, which is making them more acidic. Because oxygen is less soluble in warmer water, its concentrations in the ocean are decreasing, and dead zones are expanding.

Tipping points and long-term impacts

Different levels of global warming may cause different parts of Earth's climate system to reach tipping points that cause transitions to different states.[199][200]

Greater degrees of global warming increase the risk of passing through ' tipping points'-thresholds beyond which certain major impacts can no longer be avoided even if temperatures return to their previous state. For instance, the Greenland ice sheet is already melting, but if global warming reaches levels between 1.7 °C and 2.3 °C, its melting will continue until it fully disappears. If the warming is later reduced to 1.5 °C or less, it will still lose a lot more ice than if the warming was never allowed to reach the threshold in the first place. While the ice sheets would melt over millennia, other tipping points would occur faster and give societies less time to respond. The collapse of major ocean currents like the Atlantic meridional overturning circulation (AMOC), and irreversible damage to key ecosystems like the Amazon rainforest and coral reefs can unfold in a matter of decades.

The long-term effects of climate change on oceans include further ice melt, ocean warming, sea level rise, ocean acidification and ocean deoxygenation. The timescale of long-term impacts are centuries to millennia due to CO ₂'s long atmospheric lifetime. When net emissions stabilise surface air temperatures will also stabilise, but oceans and ice caps will continue to absorb excess heat from the atmosphere. The result is an estimated total sea level rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years. Oceanic CO ₂ uptake is slow enough that ocean acidification will also continue for hundreds to thousands of years. Deep oceans (below 2,000 metres (6,600 ft)) are also already committed to losing over 10% of their dissolved oxygen by the warming which occurred to date. Further, the West Antarctic ice sheet appears committed to practically irreversible melting, which would increase the sea levels by at least 3.3 m (10 ft 10 in) over approximately 2000 years.

Nature and wildlife

Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes. For instance, the range of hundreds of North American birds has shifted northward at an average rate of 1.5 km/year over the past 55 years. Higher atmospheric CO ₂ levels and an extended growing season have resulted in global greening. However, heatwaves and drought have reduced ecosystem productivity in some regions. The future balance of these opposing effects is unclear. A related phenomenon driven by climate change is woody plant encroachment, affecting up to 500 million hectares globally. Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics. The size and speed of global warming is making abrupt changes in ecosystems more likely. Overall, it is expected that climate change will result in the extinction of many species.

The oceans have heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles faster than species on land. Just as on land, heat waves in the ocean occur more frequently due to climate change, harming a wide range of organisms such as corals, kelp, and seabirds. Ocean acidification makes it harder for marine calcifying organisms such as mussels, barnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs. Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life. Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts. Plants have come under increased stress from damage by insects.

The effects of climate change are impacting humans everywhere in the world. Impacts can be observed on all continents and ocean regions, with low-latitude, less developed areas facing the greatest risk. Continued warming has potentially "severe, pervasive and irreversible impacts" for people and ecosystems. The risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries.

Food and health

The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century. Extreme weather leads to injury and loss of life. Various infectious diseases are more easily transmitted in a warmer climate, such as dengue fever and malaria. Crop failures can lead to food shortages and malnutrition, particularly effecting children. Both children and older people are vulnerable to extreme heat. The WHO has estimated that between 2030 and 2050, climate change would cause around 250,000 additional deaths per year. They assessed deaths from heat exposure in elderly people, increases in diarrhea, malaria, dengue, coastal flooding, and childhood malnutrition. By 2100, 50% to 75% of the global population may face climate conditions that are life-threatening due to combined effects of extreme heat and humidity.

Climate change is affecting food security. It has caused reduction in global yields of maize, wheat, and soybeans between 1981 and 2010. Future warming could further reduce global yields of major crops. Crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative. Up to an additional 183 million people worldwide, particularly those with lower incomes, are at risk of hunger as a consequence of these impacts. Climate change also impacts fish populations. Globally, less will be available to be fished. Regions dependent on glacier water, regions that are already dry, and small islands have a higher risk of water stress due to climate change.

Livelihoods and inequality

Economic damages due to climate change may be severe and there is a chance of disastrous consequences. Severe impacts are expected in South-East Asia and sub-Saharan Africa, where most of the local inhabitants are dependent upon natural and agricultural resources. Heat stress can prevent outdoor labourers from working. If warming reaches 4 °C then labour capacity in those regions could be reduced by 30 to 50%. The World Bank estimates that between 2016 and 2030, climate change could drive over 120 million people into extreme poverty without adaptation.

Inequalities based on wealth and social status have worsened due to climate change. Major difficulties in mitigating, adapting to, and recovering from climate shocks are faced by marginalised people who have less control over resources. Indigenous people, who are subsistent on their land and ecosystems, will face endangerment to their wellness and lifestyles due to climate change. An expert elicitation concluded that the role of climate change in armed conflict has been small compared to factors such as socio-economic inequality and state capabilities.

While women are not inherently more at risk from climate change and shocks, limits on women's resources and discriminatory gender norms constrain their adaptive capacity and resilience. For example, women's work burdens, including hours worked in agriculture, tend to decline less than men's during climate shocks such as heat stress.

Climate migration

Low-lying islands and coastal communities are threatened by sea level rise, which makes urban flooding more common. Sometimes, land is permanently lost to the sea. This could lead to statelessness for people in island nations, such as the Maldives and Tuvalu. In some regions, the rise in temperature and humidity may be too severe for humans to adapt to. With worst-case climate change, models project that almost one-third of humanity might live in Sahara-like uninhabitable and extremely hot climates.

These factors can drive climate or environmental migration, within and between countries. More people are expected to be displaced because of sea level rise, extreme weather and conflict from increased competition over natural resources. Climate change may also increase vulnerability, leading to "trapped populations" who are not able to move due to a lack of resources.

Reducing and recapturing emissions

Global greenhouse gas emission scenarios, based on policies and pledges as of November 2021

Climate change can be mitigated by reducing the rate at which greenhouse gases are emitted into the atmosphere, and by increasing the rate at which carbon dioxide is removed from the atmosphere. In order to limit global warming to less than 1.5 °C global greenhouse gas emissions needs to be net-zero by 2050, or by 2070 with a 2 °C target. This requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry.

The United Nations Environment Programme estimates that countries need to triple their pledges under the Paris Agreement within the next decade to limit global warming to 2 °C. An even greater level of reduction is required to meet the 1.5 °C goal. With pledges made under the Paris Agreement as of October 2021, global warming would still have a 66% chance of reaching about 2.7 °C (range: 2.2-3.2 °C) by the end of the century. Globally, limiting warming to 2 °C may result in higher economic benefits than economic costs.

Although there is no single pathway to limit global warming to 1.5 or 2 °C, most scenarios and strategies see a major increase in the use of renewable energy in combination with increased energy efficiency measures to generate the needed greenhouse gas reductions. To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry, such as preventing deforestation and restoring natural ecosystems by reforestation.

Other approaches to mitigating climate change have a higher level of risk. Scenarios that limit global warming to 1.5 °C typically project the large-scale use of carbon dioxide removal methods over the 21st century. There are concerns, though, about over-reliance on these technologies, and environmental impacts. Solar radiation modification (SRM) is also a possible supplement to deep reductions in emissions. However, SRM raises significant ethical and legal concerns, and the risks are imperfectly understood.

Clean energy

Coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing.[278]

Wind and solar power, Germany

Renewable energy is key to limiting climate change. For decades, fossil fuels have accounted for roughly 80% of the world's energy use. The remaining share has been split between nuclear power and renewables (including hydropower, bioenergy, wind and solar power and geothermal energy). Fossil fuel use is expected to peak in absolute terms prior to 2030 and then to decline, with coal use experiencing the sharpest reductions. Renewables represented 75% of all new electricity generation installed in 2019, nearly all solar and wind. Other forms of clean energy, such as nuclear and hydropower, currently have a larger share of the energy supply. However, their future growth forecasts appear limited in comparison.

While solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations, green energy policies are needed to achieve a rapid transition from fossil fuels to renewables. To achieve carbon neutrality by 2050, renewable energy would become the dominant form of electricity generation, rising to 85% or more by 2050 in some scenarios. Investment in coal would be eliminated and coal use nearly phased out by 2050.

Electricity generated from renewable sources would also need to become the main energy source for heating and transport. Transport can switch away from internal combustion engine vehicles and towards electric vehicles, public transit, and active transport (cycling and walking). For shipping and flying, low-carbon fuels would reduce emissions. Heating could be increasingly decarbonised with technologies like heat pumps.

There are obstacles to the continued rapid growth of clean energy, including renewables. For wind and solar, there are environmental and land use concerns for new projects. Wind and solar also produce energy intermittently and with seasonal variability. Traditionally, hydro dams with reservoirs and conventional power plants have been used when variable energy production is low. Going forward, battery storage can be expanded, energy demand and supply can be matched, and long-distance transmission can smooth variability of renewable outputs. Bioenergy is often not carbon-neutral and may have negative consequences for food security. The growth of nuclear power is constrained by controversy around radioactive waste, nuclear weapon proliferation, and accidents. Hydropower growth is limited by the fact that the best sites have been developed, and new projects are confronting increased social and environmental concerns.

Low-carbon energy improves human health by minimising climate change as well as reducing air pollution deaths, which were estimated at 7 million annually in 2016. Meeting the Paris Agreement goals that limit warming to a 2 °C increase could save about a million of those lives per year by 2050, whereas limiting global warming to 1.5 °C could save millions and simultaneously increase energy security and reduce poverty. Improving air quality also has economic benefits which may be larger than mitigation costs.

Energy conservation

Reducing energy demand is another major aspect of reducing emissions. If less energy is needed, there is more flexibility for clean energy development. It also makes it easier to manage the electricity grid, and minimises carbon-intensive infrastructure development. Major increases in energy efficiency investment will be required to achieve climate goals, comparable to the level of investment in renewable energy. Several COVID-19 related changes in energy use patterns, energy efficiency investments, and funding have made forecasts for this decade more difficult and uncertain.

Strategies to reduce energy demand vary by sector. In the transport sector, passengers and freight can switch to more efficient travel modes, such as buses and trains, or use electric vehicles. Industrial strategies to reduce energy demand include improving heating systems and motors, designing less energy-intensive products, and increasing product lifetimes. In the building sector the focus is on better design of new buildings, and higher levels of energy efficiency in retrofitting. The use of technologies like heat pumps can also increase building energy efficiency.

Agriculture and industry

Taking into account direct and indirect emissions, industry is the sector with the highest share of global emissions. Data as of 2019 from the IPCC.

Agriculture and forestry face a triple challenge of limiting greenhouse gas emissions, preventing the further conversion of forests to agricultural land, and meeting increases in world food demand. A set of actions could reduce agriculture and forestry-based emissions by two thirds from 2010 levels. These include reducing growth in demand for food and other agricultural products, increasing land productivity, protecting and restoring forests, and reducing greenhouse gas emissions from agricultural production.

On the demand side, a key component of reducing emissions is shifting people towards plant-based diets. Eliminating the production of livestock for meat and dairy would eliminate about 3/4ths of all emissions from agriculture and other land use. Livestock also occupy 37% of ice-free land area on Earth and consume feed from the 12% of land area used for crops, driving deforestation and land degradation.

Steel and cement production are responsible for about 13% of industrial CO ₂ emissions. In these industries, carbon-intensive materials such as coke and lime play an integral role in the production, so that reducing CO ₂ emissions requires research into alternative chemistries.

Carbon sequestration

Most CO₂ emissions have been absorbed by carbon sinks, including plant growth, soil uptake, and ocean uptake (2020 Global Carbon Budget).

Natural carbon sinks can be enhanced to sequester significantly larger amounts of CO ₂ beyond naturally occurring levels. Reforestation and afforestation (planting forests where there were none before) are among the most mature sequestration techniques, although the latter raises food security concerns. Farmers can promote sequestration of carbon in soils through practices such as use of winter cover crops, reducing the intensity and frequency of tillage, and using compost and manure as soil amendments. Forest and landscape restoration yields many benefits for the climate, including greenhouse gas emissions sequestration and reduction. Restoration/recreation of coastal wetlands, prairie plots and seagrass meadows increases the uptake of carbon into organic matter. When carbon is sequestered in soils and in organic matter such as trees, there is a risk of the carbon being re-released into the atmosphere later through changes in land use, fire, or other changes in ecosystems.

Where energy production or CO ₂-intensive heavy industries continue to produce waste CO ₂, the gas can be captured and stored instead of released to the atmosphere. Although its current use is limited in scale and expensive, carbon capture and storage (CCS) may be able to play a significant role in limiting CO ₂ emissions by mid-century. This technique, in combination with bioenergy ( BECCS) can result in net negative emissions as CO ₂ is drawn from the atmosphere. It remains highly uncertain whether carbon dioxide removal techniques will be able to play a large role in limiting warming to 1.5 °C. Policy decisions that rely on carbon dioxide removal increase the risk of global warming rising beyond international goals.

Adaptation

Adaptation is "the process of adjustment to current or expected changes in climate and its effects". Without additional mitigation, adaptation cannot avert the risk of "severe, widespread and irreversible" impacts. More severe climate change requires more transformative adaptation, which can be prohibitively expensive. The capacity and potential for humans to adapt is unevenly distributed across different regions and populations, and developing countries generally have less. The first two decades of the 21st century saw an increase in adaptive capacity in most low- and middle-income countries with improved access to basic sanitation and electricity, but progress is slow. Many countries have implemented adaptation policies. However, there is a considerable gap between necessary and available finance.

Adaptation to sea level rise consists of avoiding at-risk areas, learning to live with increased flooding, and building flood controls. If that fails, managed retreat may be needed. There are economic barriers for tackling dangerous heat impact. Avoiding strenuous work or having air conditioning is not possible for everybody. In agriculture, adaptation options include a switch to more sustainable diets, diversification, erosion control, and genetic improvements for increased tolerance to a changing climate. Insurance allows for risk-sharing, but is often difficult to get for people on lower incomes. Education, migration and early warning systems can reduce climate vulnerability. Planting mangroves or encouraging other coastal vegetation can buffer storms.

Ecosystems adapt to climate change, a process that can be supported by human intervention. By increasing connectivity between ecosystems, species can migrate to more favourable climate conditions. Species can also be introduced to areas acquiring a favorable climate. Protection and restoration of natural and semi-natural areas helps build resilience, making it easier for ecosystems to adapt. Many of the actions that promote adaptation in ecosystems, also help humans adapt via ecosystem-based adaptation. For instance, restoration of natural fire regimes makes catastrophic fires less likely, and reduces human exposure. Giving rivers more space allows for more water storage in the natural system, reducing flood risk. Restored forest acts as a carbon sink, but planting trees in unsuitable regions can exacerbate climate impacts.

There are synergies but also trade-offs between adaptation and mitigation. An example for synergy is increased food productivity, which has large benefits for both adaptation and mitigation. An example of a trade-off is that increased use of air conditioning allows people to better cope with heat, but increases energy demand. Another trade-off example is that more compact urban development may reduce emissions from transport and construction, but may also increase the urban heat island effect, exposing people to heat-related health risks.

Policies and politics

The Climate Change Performance Index ranks countries by greenhouse gas emissions (40% of score), renewable energy (20%), energy use (20%), and climate policy (20%).

Countries that are most vulnerable to climate change have typically been responsible for a small share of global emissions. This raises questions about justice and fairness. Limiting global warming makes it much easier to achieve the UN's Sustainable Development Goals, such as eradicating poverty and reducing inequalities. The connection is recognised in Sustainable Development Goal 13 which is to "take urgent action to combat climate change and its impacts". The goals on food, clean water and ecosystem protection have synergies with climate mitigation.

The geopolitics of climate change is complex. It has often been framed as a free-rider problem, in which all countries benefit from mitigation done by other countries, but individual countries would lose from switching to a low-carbon economy themselves. Sometimes mitigation also has localised benefits though. For instance, the benefits of a coal phase-out to public health and local environments exceed the costs in almost all regions. Furthermore, net importers of fossil fuels win economically from switching to clean energy, causing net exporters to face stranded assets: fossil fuels they cannot sell.

Policy options

A wide range of policies, regulations, and laws are being used to reduce emissions. As of 2019, carbon pricing covers about 20% of global greenhouse gas emissions. Carbon can be priced with carbon taxes and emissions trading systems. Direct global fossil fuel subsidies reached $319 billion in 2017, and $5.2 trillion when indirect costs such as air pollution are priced in. Ending these can cause a 28% reduction in global carbon emissions and a 46% reduction in air pollution deaths. Money saved on fossil subsidies could be used to support the transition to clean energy instead. More direct methods to reduce greenhouse gases include vehicle efficiency standards, renewable fuel standards, and air pollution regulations on heavy industry. Several countries require utilities to increase the share of renewables in power production.

Climate justice

Policy designed through the lens of climate justice tries to address human rights issues and social inequality. According to proponents of climate justice, the costs of climate adaptation should be paid by those most responsible for climate change, while the beneficiaries of payments should be those suffering impacts. One way this can be addressed in practice is to have wealthy nations pay poorer countries to adapt.

Oxfam found that in 2023 the wealthiest 10% of people were responsible for 50% of global emissions, while the bottom 50% were responsible for just 8%. Production of emissions is another way to look at responsibility: under that approach, the top 21 fossil fuel companies would owe cumulative climate reparations of $5.4 trillion over the period 2025-2050. To achieve a just transition, people working in the fossil fuel sector would also need other jobs, and their communities would need investments.

International climate agreements

Since 2000, rising CO₂ emissions in China and the rest of world have surpassed the output of the United States and Europe.[358]

Per person, the United States generates CO₂ at a far faster rate than other primary regions.[358]

Nearly all countries in the world are parties to the 1994 United Nations Framework Convention on Climate Change (UNFCCC). The goal of the UNFCCC is to prevent dangerous human interference with the climate system. As stated in the convention, this requires that greenhouse gas concentrations are stabilised in the atmosphere at a level where ecosystems can adapt naturally to climate change, food production is not threatened, and economic development can be sustained. The UNFCCC does not itself restrict emissions but rather provides a framework for protocols that do. Global emissions have risen since the UNFCCC was signed. Its yearly conferences are the stage of global negotiations.

The 1997 Kyoto Protocol extended the UNFCCC and included legally binding commitments for most developed countries to limit their emissions. During the negotiations, the G77 (representing developing countries) pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions, since developed countries contributed most to the accumulation of greenhouse gases in the atmosphere. Per-capita emissions were also still relatively low in developing countries and developing countries would need to emit more to meet their development needs.

The 2009 Copenhagen Accord has been widely portrayed as disappointing because of its low goals, and was rejected by poorer nations including the G77. Associated parties aimed to limit the global temperature rise to below 2 °C. The Accord set the goal of sending $100 billion per year to developing countries for mitigation and adaptation by 2020, and proposed the founding of the Green Climate Fund. As of 2020, only 83.3 billion were delivered. Only in 2023 the target is expected to be achieved.

In 2015 all UN countries negotiated the Paris Agreement, which aims to keep global warming well below 2.0 °C and contains an aspirational goal of keeping warming under 1.5 °C. The agreement replaced the Kyoto Protocol. Unlike Kyoto, no binding emission targets were set in the Paris Agreement. Instead, a set of procedures was made binding. Countries have to regularly set ever more ambitious goals and reevaluate these goals every five years. The Paris Agreement restated that developing countries must be financially supported. As of October 2021, 194 states and the European Union have signed the treaty and 191 states and the EU have ratified or acceded to the agreement.

The 1987 Montreal Protocol, an international agreement to stop emitting ozone-depleting gases, may have been more effective at curbing greenhouse gas emissions than the Kyoto Protocol specifically designed to do so. The 2016 Kigali Amendment to the Montreal Protocol aims to reduce the emissions of hydrofluorocarbons, a group of powerful greenhouse gases which served as a replacement for banned ozone-depleting gases. This made the Montreal Protocol a stronger agreement against climate change.

National responses

In 2019, the United Kingdom parliament became the first national government to declare a climate emergency. Other countries and jurisdictions followed suit. That same year, the European Parliament declared a "climate and environmental emergency". The European Commission presented its European Green Deal with the goal of making the EU carbon-neutral by 2050. In 2021, the European Commission released its " Fit for 55" legislation package, which contains guidelines for the car industry; all new cars on the European market must be zero-emission vehicles from 2035.

Major countries in Asia have made similar pledges: South Korea and Japan have committed to become carbon-neutral by 2050, and China by 2060. While India has strong incentives for renewables, it also plans a significant expansion of coal in the country. Vietnam is among very few coal-dependent, fast-developing countries that pledged to phase out unabated coal power by the 2040s or as soon as possible thereafter.

As of 2021, based on information from 48 national climate plans, which represent 40% of the parties to the Paris Agreement, estimated total greenhouse gas emissions will be 0.5% lower compared to 2010 levels, below the 45% or 25% reduction goals to limit global warming to 1.5 °C or 2 °C, respectively.

Denial and misinformation

Data has been cherry picked from short periods to falsely assert that global temperatures are not rising. Blue trendlines show short periods that mask longer-term warming trends (red trendlines). Blue rectangle with blue dots shows the so-called global warming hiatus.

Public debate about climate change has been strongly affected by climate change denial and misinformation, which originated in the United States and has since spread to other countries, particularly Canada and Australia. Climate change denial has originated from fossil fuel companies, industry groups, conservative think tanks, and contrarian scientists. Like the tobacco industry, the main strategy of these groups has been to manufacture doubt about climate-change related scientific data and results. People who hold unwarranted doubt about climate change are called climate change "skeptics", although "contrarians" or "deniers" are more appropriate terms.

There are different variants of climate denial: some deny that warming takes place at all, some acknowledge warming but attribute it to natural influences, and some minimise the negative impacts of climate change. Manufacturing uncertainty about the science later developed into a manufactured controversy: creating the belief that there is significant uncertainty about climate change within the scientific community in order to delay policy changes. Strategies to promote these ideas include criticism of scientific institutions, and questioning the motives of individual scientists. An echo chamber of climate-denying blogs and media has further fomented misunderstanding of climate change.

Public awareness and opinion

The public substantially underestimates the degree of scientific consensus that humans are causing climate change.[394] Studies from 2019 to 2021[395][4][396] found scientific consensus to range from 98.7 to 100%.

Climate change came to international public attention in the late 1980s. Due to media coverage in the early 1990s, people often confused climate change with other environmental issues like ozone depletion. In popular culture, the climate fiction movie The Day After Tomorrow (2004) and the Al Gore documentary An Inconvenient Truth (2006) focused on climate change.

Significant regional, gender, age and political differences exist in both public concern for, and understanding of, climate change. More highly educated people, and in some countries, women and younger people, were more likely to see climate change as a serious threat. Partisan gaps also exist in many countries, and countries with high CO ₂ emissions tend to be less concerned. Views on causes of climate change vary widely between countries. Concern has increased over time, to the point where in 2021 a majority of citizens in many countries express a high level of worry about climate change, or view it as a global emergency. Higher levels of worry are associated with stronger public support for policies that address climate change.

Climate movement

Climate protests demand that political leaders take action to prevent climate change. They can take the form of public demonstrations, fossil fuel divestment, lawsuits and other activities. Prominent demonstrations include the School Strike for Climate. In this initiative, young people across the globe have been protesting since 2018 by skipping school on Fridays, inspired by Swedish teenager Greta Thunberg. Mass civil disobedience actions by groups like Extinction Rebellion have protested by disrupting roads and public transport.

Litigation is increasingly used as a tool to strengthen climate action from public institutions and companies. Activists also initiate lawsuits which target governments and demand that they take ambitious action or enforce existing laws on climate change. Lawsuits against fossil-fuel companies generally seek compensation for loss and damage.

Early discoveries

Scientists in the 19th century such as Alexander von Humboldt began to foresee the effects of climate change. In the 1820s, Joseph Fourier proposed the greenhouse effect to explain why Earth's temperature was higher than the Sun's energy alone could explain. Earth's atmosphere is transparent to sunlight, so sunlight reaches the surface where it is converted to heat. However, the atmosphere is not transparent to heat radiating from the surface, and captures some of that heat, which in turn warms the planet.

In 1856 Eunice Newton Foote demonstrated that the warming effect of the Sun is greater for air with water vapour than for dry air, and that the effect is even greater with carbon dioxide (CO ₂). She concluded that "An atmosphere of that gas would give to our earth a high temperature..."

Studying what would become known as the greenhouse effect, Tyndall's pre-1861 ratio spectrophotometer measured how much various gases in a tube absorb and emit infrared radiation-which humans experience as heat.

Starting in 1859, John Tyndall established that nitrogen and oxygen-together totaling 99% of dry air-are transparent to radiated heat. However, water vapour and gases such as methane and carbon dioxide absorb radiated heat and re-radiate that heat into the atmosphere. Tyndall proposed that changes in the concentrations of these gases may have caused climatic changes in the past, including ice ages.

Svante Arrhenius noted that water vapour in air continuously varied, but the CO ₂ concentration in air was influenced by long-term geological processes. Warming from increased CO ₂ levels would increase the amount of water vapour, amplifying warming in a positive feedback loop. In 1896, he published the first climate model of its kind, projecting that halving CO ₂ levels could have produced a drop in temperature initiating an ice age. Arrhenius calculated the temperature increase expected from doubling CO ₂ to be around 5-6 °C. Other scientists were initially skeptical and believed that the greenhouse effect was saturated so that adding more CO ₂ would make no difference, and that the climate would be self-regulating. Beginning in 1938, Guy Stewart Callendar published evidence that climate was warming and CO ₂ levels were rising, but his calculations met the same objections.

Development of a scientific consensus

Scientific consensus on causation: Academic studies of scientific agreement on human-caused global warming among climate experts (2010-2015) reflect that the level of consensus correlates with expertise in climate science.[423] A 2019 study found scientific consensus to be at 100%,[424] and a 2021 study concluded that consensus exceeded 99%.[425] Another 2021 study found that 98.7% of climate experts indicated that the Earth is getting warmer mostly because of human activity.[426]

In the 1950s, Gilbert Plass created a detailed computer model that included different atmospheric layers and the infrared spectrum. This model predicted that increasing CO ₂ levels would cause warming. Around the same time, Hans Suess found evidence that CO ₂ levels had been rising, and Roger Revelle showed that the oceans would not absorb the increase. The two scientists subsequently helped Charles Keeling to begin a record of continued increase, which has been termed the " Keeling Curve". Scientists alerted the public, and the dangers were highlighted at James Hansen's 1988 Congressional testimony. The Intergovernmental Panel on Climate Change (IPCC), set up in 1988 to provide formal advice to the world's governments, spurred interdisciplinary research. As part of the IPCC reports, scientists assess the scientific discussion that takes place in peer-reviewed journal articles.

There is a near-complete scientific consensus that the climate is warming and that this is caused by human activities. As of 2019, agreement in recent literature reached over 99%. No scientific body of national or international standing disagrees with this view. Consensus has further developed that some form of action should be taken to protect people against the impacts of climate change. National science academies have called on world leaders to cut global emissions. The 2021 IPCC Assessment Report stated that it is "unequivocal" that climate change is caused by humans.

References

1. ^ EPA (19 January 2017). "Climate Impacts on Ecosystems". Archived from the original on 27 January 2018. Mountain and arctic ecosystems and species are particularly sensitive to climate change... As ocean temperatures warm and the acidity of the ocean increases, bleaching and coral die-offs are likely to become more frequent.

2. ^ IPCC SR15 Ch1 2018, p. 64: Sustained net zero anthropogenic emissions of CO₂ and declining net anthropogenic non-CO₂ radiative forcing over a multi-decade period would halt anthropogenic global warming over that period, although it would not halt sea level rise or many other aspects of climate system adjustment.

3. Cattaneo et al. 2019; IPCC AR6 WG2 2022, pp. 15, 53

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7. Weart "The Public and Climate Change: The Summer of 1988", "News reporters gave only a little attention ...".

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This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 ( license statement/permission). Text taken from The status of women in agrifood systems - Overview​, FAO, FAO.

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# data[].attributes.attachment_link.description
In common usage, climate change describes global warming-the ongoing increase in global average temperature-and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is primarily caused by humans burning fossil fuels since the Industrial Revolution.

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Click here to read Part I of this series: "Why California Must Declare A State Of Emergency On Homelessness -- Or Get A Governor Who Will"
On Tuesday, fifteen officials from the White House toured Skid Row in Los Angeles with the head of a local homeless shelter. "Four or five of them were from the Environmental Protection Agency," Rev. Andy Bales of Union Mission church told me. "That's because human waste flows into storm sewers."

California is home to some of the world's toughest environmental and public health laws, but skyrocketing homelessness has created an environmental and public health disaster. The 44,000 people living, eating, and defecating on the streets of L.A. have brought rats and medieval diseases including typhus. Garbage is everywhere. Experts fear the return of cholera and leprosy.

And homelessness is making people violent. "We are seeing behaviors from our guests that I've never seen in 33 years," said Bales. "They are so bizarre and different that I don't even feel right describing the behaviors. It's extreme violence of an extreme sexual nature. I have been doing this for 33 years and never seen anything like it."

Bales says he was one of the people who urged the US Government's Federal Emergency Management Administration (FEMA) to intervene. "We've been crying out for a National Guard-like response," said Bales, whose church provides food, showers, and shelter to 1,350 people camped nearby. In 2016 Bales lost the lower half of his leg to a flesh-eating bacteria from contamination on Skid Row.

How did things get so bad in California? The state has long prided itself on being humanistic and innovative. It is home to some of the world's largest public health philanthropies, best hospitals, and most progressive policies on mental health and drug addiction. The Democrats have a supermajority. What went wrong?

According to Bales and other experts, California made homelessness worse by making perfect housing the enemy of good housing, by liberalizing drug laws, and by opposing mandatory treatment for mental illness and drug addiction.

Other states have done a better job despite spending less money. "This isn't rocket science," said John Snook, who runs the Treatment Advocacy Center , which advises states on mental health and homelessness policy around the country. "Arizona is a red state that doesn't spend a ton on its services but is the best scenario in every aspect. World-class coordination with law enforcement. Strong oversight. They don't let people fall apart and then return to jail in 30 days like California does."

What happened in California isn't the first time that we progressives let our idealism get the better of us. To understand how the current disaster unfolded, we have to go back in time, back to the post-World War II era when progressive reformers convinced themselves and others that they could destroy the country's system for dealing with the mentally ill and replace it with a radically different and wholly unproven alternative.
A Mania for Reform
People considered the creation of state mental institutions in the 1800s to be a major progressive reform because they took the mentally ill out of prisons and hospitals and put them into a safer and kinder environment, the psychiatrist E. Fuller Torrey, M.D., in his devastating and critically-acclaimed 2014 history, American Psychosis: How the Federal Government Destroyed the Mental Illness System.

In many respects, the mental institutions were a step in the right direction, but by the middle of the 20th Century, their reputation was in tatters. They were understaffed and overcrowded. Some patients were poorly treated, even abused. Others were neglected. During World War II, Mennonites and Quakers worked in the institutions as an alternative to military service. After the war, they drew attention to the deplorable conditions.

Reformers felt they could do better. In 1945 they proposed community-based clinics not just to treat but also to prevent mental illness. They called for a federal takeover. Congressional advocates frequently invoked the US government's Manhattan Project as inspiration. If America could build a nuclear bomb in a few years, why couldn't we prevent and cure mental illness?

As Congress debated mental health reform in 1946, some were suspicious. "Men get strange ideas," said Republican congressman Clarence J. Brown of Ohio. "They decide the only way in the world they are going to solve all the problems of mankind is to do a certain thing and that their field is the most important." Many reformers believed mental illness was created by poverty and inequality and argued that solving it required creating "mentally healthy" environments, organizing tenants, and fighting landlords.

These reformers viewed mental illnesses like schizophrenia and bipolar disorder as socially constructed and not the result of biology, as most doctors believe today. They sought clinics that would "promote health" and "the development of a resilient character." They wanted clinics to treat the "totality of [a patient's] being in the totality of his relationships." The psychiatrist played a special role, the reformers said. "One might even say," wrote Francis Braceland, an influential psychiatrist who had studied with Carl Jung, " the ideal goal of the psychiatrist is to achieve wisdom."

The reformers were so confident in their convictions that they smashed the state mental institutions before creating an alternative. The reformers hyped new psychiatric drugs, which reduced the symptoms of schizophrenia, as a bridge to the new system. There was little resistance to the radical changes by existing mental institutions, whose leadership had been demoralized and discredited. And yet there was no evidence that community-based treatment would work. Between 1948 and 1962, the test that clinic reformers pointed to as the model had not prevented a single case of mental illness or treated a single individual with schizophrenia.

But attacking mental institutions had become hugely popular. In two hugely influential 1961 books, a psychiatrist argued that mental illnesses didn't exist and a sociologist argued that the institutions themselves created mental illness. One year later, One Flew Over the Cuckoo's Nest , a novel about a sane but socially maladjusted man who was drugged, electro-shocked, and lobotomized by a mental institution, became a best-seller. In 1967, the film "King of Hearts" depicted psychiatric inmates after World War II as living happily once freed from their asylum. In 1975, the year "One Flew Over the Cuckoo's Nest" became a hit film, Michel Foucault argued in Discipline and Punish that mentally ill people had been better off in the Middle Ages when they could roam the streets without being shamed as deviant.

Over the next two decades, state mental hospitals would empty out. But the vast majority of released patients ended up homeless on the street. Congress had "encouraged the closing of state mental hospitals without any realistic plan regarding what would happen to the discharged patients," notes Dr. Torrey, "especially those who refused to take medication they needed to remain well."

And yet the reformers were becoming only more radical. "The changes I am talking about," said a leader at the new National Institute of Mental Health, " involves a redistribution of wealth and resources... society for the urban poor of such beauty and richness... nothing less than a privilege to be called poor."

But when the community mental health clinics did start operating, they tended to treat the easiest-to-treat, not the hardest. It was a trend that worsened the longer the clinics were in existence. The clinic saw "very few individuals with serious mental illnesses," reported a young psychiatrist working in Santa Monica near LA. "Instead, the patients were people from the community with various personal crises."

In the end, no more than 5% of the federally-funded clinics "made any significant contributions to the care of patients being released from state mental hospitals," finds Torrey. Financial abuses were rife, with clinics building tennis courts, swimming pools, and rooms for fads like "inhalation therapy" that did nothing for people with schizophrenia.

When critics faulted the clinics for their abuses, reformers defended themselves behind a wall of political correctness. One reformer-aligned task force that investigated the situation concluded in 1976 that "to criticize the [mental health] centers themselves for many (but not all) of their failings is to 'blame the victim!'" The Carter Administration recommended making federal support permanent and included new money to prevent mental illness by reducing "societal stresses produced by racism, poverty, sexism, ageism, and urban blight."

Republicans who had initially supported deinstitutionalization as a cost-savings measure became increasingly resentful of what they viewed as an anarchistic approach and sought to cut the budget for mental illness. But as federal support for the clinics declined, the state institutions were no longer in place to care for the homeless evicted to the streets. Everybody was in charge and nobody was in charge. The reformers grew depressed. "The deformed creature that has developed from the original community mental health center movement does not arouse much enthusiasm in any of us who had some more grandiose visions," said one.

The problem, Torrey and other advocates for the mentally ill say, wasn't de-institutionalization but rather the failure to provide new forms of treatment. "The majority of lives were little different than they had had while hospitalized," he concludes, "and a significant number were considerably worse off." Many didn't even realize they were mentally ill, similar to some Alzheimer's patients. For decades, radical reformers sought de-institutionalization in even the most extreme situations. In 1985, a public defender got a mentally ill client released from jail even though he had been found eating his feces.

Importantly, reformers never had evidence that community-based clinics would work better than big institutions. They just assumed it in a way that is eerily similar to the way that 1960s environmentalists in California, including Governor Jerry Brown, assumed "small-is-beautiful" policies would be better for the environment. Out of hubris, the reformers sought to smash the old institution before creating a new one. Intriguingly, that's exactly what reformers would do again in California, 50 years later.
When Dogmatism Is Deadly
For decades, many progressives have claimed that homelessness is really just a kind of poverty, a manifestation of social inequality. In 1986, celebrity comedians Whoopi Goldberg, Robin Williams, and Billy Crystal held "Comic Relief," a telethon for homelessness. Throughout it, they emphasized that the homeless were just like you and me, just poorer. Today, many of California's leading homelessness advocates insist that the current crisis is due mostly to the housing shortage.

Homelessness experts and advocates disagree. "I've rarely seen a normal able-bodied able-minded non-drug-using homeless person who's just down on their luck," L.A. street doctor Susan Partovi told me. "Of the thousands of people I've worked with over 16 years, it's like one or two people a year. And they're the easiest to deal with." Rev. Bales agrees. "One hundred percent of the people on the streets are mentally impacted, on drugs, or both," he said.

Most of the time what people mean by the homelessness problem is really a drug problem and a mental illness problem. "The problem is we don't know if you're psychotic or just on meth," said Dr. Partovi. "And giving it up is very difficult. I worked in the local jail, and half of the inmates in the women's jail were Latinas in their 20s, and all were in there for something related to meth."

The people who work directly with the homeless say things worsened after California abandoned the "carrot and stick" approach toward treating the severely mentally ill and drug addicts who are repeat offenders. "The ACLU will come after me if I say the mentally ill need to be taken off the street," said Dr. Partovi, "so let me be clear that they need to be taken care of, too."

Bales says things worsened ten years ago when L.A. and other California cities rejected drug recovery (treatment) as a condition of housing. "When the 'Housing First' with a harm reduction model people came in they said 'Recovery doesn't work,'" said Bales. "But it was after that when homelessness exploded exponentially."

Bales says people have little incentive to do treatment when there is no threat of jail time. "[The Housing First harm reduction advocates] talked about new services, but they were all voluntary." Things went further in this direction with the passage of Proposition 47 in 2014, which decriminalized hard drugs and released nonviolent offenders from prison without providing after-care support. "Our guests went from 12 - 17% addicted to 50% or higher," Bales says. "Policymakers need to understand that if you allow the use, you also allow the sales, and if you allow the sales, then you allow the big guys to break your legs when you owe them money," says Bales.

Snook says that California is so unwilling to require non-voluntary mental health care that it is only now considering more extensive "conservatorship" - where a health official is given the authority to make decisions for a mentally incapacitated individual - and only after nine acts of violence against themselves or others.

"Imagine having a sick child and hoping he attacks someone once a month so somebody can do something!" said Snook. "That is so out of sync with the rest of the country, and with what mental health care looks like, that it is laughable."

Lack of shelter and leadership are factors alongside extreme progressive idealism. "It's the impact of not having a stick and not having shelter," says Bales. Snook agrees. "There's a provision that says Medicaid will now pay for beds in psychiatric hospitals," said Snook. "It's a no-brainer, but California is hemming and hawing. They don't want to involuntarily incarcerate, but it's self-defeating because you end up with mentally ill in jail because a bed isn't available."

Is the problem a lack of money? "California spends more than most places," said Snook, whose organization researches and advocates solutions for mentally ill homeless people nationally. What happened to the money from Proposition 63, the successful 2004 ballot initiative that taxed millionaires for mental health? "A Hoover Foundation audit found funds that were supposed to go to seriously mentally ill were used for yoga and trauma and other laudable things, but none for the seriously mentally ill," said Snook.

"When you look at the amount of money being spent, and then you hear the argument that we need more money? You have to ask, 'How much more?'" said Snook. "Right now it's just good money after bad. There's no oversight and no accountability."

Liberal idealism also wasted much of the $1.2 billion that L.A. voters raised in 2016 when they voted to tax themselves to build housing for the homeless. "It was supposed to build 10,000 units but in truth will create half that because each one costs $527,000 to $700,000," said Bales. "They will take ten years to build, at which point 44,000 lives will have been destroyed by living on the street."

Why did progressive housing activists in L.A. insist on building such expensive apartments for so few people, so slowly, rather than quickly building cheaper units faster for 44,000 people?

"[Housing First] is a dogmatic philosophy," said Bales. "I've lost friends. One of my closest friends is attacking me for pushing for housing that costs $11,000 instead of $527,000 per person. He can't get that we can't provide a $527,000 to $700,000 apartment for each person on the street. I've been in planning meetings where people said, 'Everybody deserves a granite countertop,' but that isn't going to work for 44,000 people."

L.A.'s woke housing advocates have intimidated the city's mayor. "I think the mayor's unwilling to put out bridge shelters because of backlash from some homeless advocates," said Bales, "and is concerned about NIMBYs, and may be concerned about union workers because the shelters may not be built by the unions."
Beyond Right and Left
Despite the emergency, and in some ways because of it, homeless reformers are hopeful today that California will seek a more moderate path toward treating mental illness and drug addiction and providing shelter. "The problem is so bad and so significant that there's an opportunity now," said Snook.

Bales agrees. "In New York where they put a roof over the heads of 95% of the homeless, it took a law to change things," he said. "I thought it would take a law here, too, but maybe we can get there without a law if people continue to show political courage."

California recently awarded L.A. $124 million for the homelessness emergency, of which L.A.'s mayor has spent $66 million on 27 cheap, quick-to-assemble temporary shelters that can quickly get 13,000 people off the street. "I think the mayor has been fighting an uphill battle against the powers that be, and his political courage is growing," said Bales.

One sign of trouble was the resistance by some in California to receiving help from the federal government. "[Trump's] budget has proposed slashing public housing ... and eliminating community development block grant dollars," LA's mayor . "It's totally out of step with the idea that he's here to help."

But others were more conciliatory "I am wary of any such offer from an administration that consistently demonizes vulnerable people," the governor's top homelessness advisor, Sacramento Mayor Darrell Steinberg, told me "And yet, if the federal government wants to offer resources to help bring people indoors and to offer federal facilities to shelter and house people, we should readily listen. We cannot afford to politicize an issue which needs real thought and real commitment."

Everyone I spoke to hopes that the current crisis makes all sides less dogmatic. Something like that happened at the federal level after a mentally ill man killed 20 elementary school children in 2012. Democrats and Republicans found common ground on sweeping mental health reform legislation in 2015. "It wasn't a Democrat or Republican thing," says Snook.

Steinberg, for his part, would like to see legislation codifying his "right/obligation to shelter" framework, which blends the traditional liberal emphasis on rights and care with the traditional conservative emphasis on order. "I'm open to more carrots and sticks and would be for an obligation to seek shelter. I don't think living outside is a civil right," he told me. "We back, philosophically, 'Housing First'... but if all we did was permanent housing, it would be until 2037 before we housed every person on the streets in the Bay Area."

It's hard to see any of what needs to happen as particularly partisan. "The key is focusing services on the seriously ill," argues Snook. "You provide extended care. You open up beds for when they are stable. You provide care to people to stay out of the system." What about the homeless who are not mentally ill? Focus on the hardest population first, he urged. "Once you get that population addressed, you can move on to the others. This is what New York City did. Once you get that population serviced, you're not in crisis mode anymore, and you free up money for everyone else."

I left the reporting for this column surprised by how stuck California's leaders remain in 1960s ideology and how slow they've been to react to the crisis. "It's better late than never, but still we are not treating it in the urgent manner we should," said Bales. "We're not there yet where people are really taking it seriously as an emergency." For Torrey, it all comes down to leadership. "It is not clear where the leadership for change will come from," he wrote seven years ago, "but until it emerges, change is unlikely."

... Read More

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Why California Keeps Making Homelessness Worse

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Click here to read Part I of this series: "Why California Must Declare A State Of Emergency On Homelessness -- Or Get A Governor Who Will" On Tuesday, fifteen officials from the White House toured Skid Row in Los Angeles with the head of a local homeless shelter.

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Racial Discrimination, Ethnic-Racial Socialization, and Crime: A Micro-sociological Model of Risk and Resilience

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Dominant theoretical explanations of racial disparities in criminal offending overlook a key risk factor associated with race: interpersonal racial discrimination. Building on recent studies that analyze race and crime at the micro-level, we specify a…

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Feminism Claims to Represent All Women. So Why Does It Ignore So Many of Them?

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In her new book Hood Feminism, Mikki Kendall argues that mainstream feminism focuses on increasing privilege rather than addressing basic needs.

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John

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Causes Of Homelessness | The Homeless Hub

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People who experience homelessness are not distinct or separate from the rest of the population. In fact, the line between being housed and unhoused is quite fluid. In general, the pathways into and out of homelessness are neither linear nor uniform. Individuals and families who experience homelessness may not share much in common with each other, aside from the fact that they are extremely vulnerable and lack adequate housing, income and the necessary supports to ensure they stay housed. The causes of homelessness reflect an intricate interplay between structural factors, systems failures and individual circumstances. Homelessness is usually the result of the cumulative impact of a number of factors, rather than a single cause.

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Read below for some basic facts about homelessness. For more information, check out these resources:

Why Are People Homeless?

Housing

A lack of affordable housing and the limited scale of housing assistance programs have contributed to the current housing crisis and to homelessness. Recently, foreclosures have also increased the number of people who experience homelessness.
The National Low Income Housing Coalition estimates that the 2017 Housing Wage is $21.21 per hour, exceeding the $16.38 hourly wage earned by the average renter by almost $5.00 an hour, and greatly exceeding wages earned by low income renter households. In fact, the hourly wage needed for renters hoping to afford a two-bedroom rental home is $13.96 higher than the national minimum wage of $7.25.

Poverty

Homelessness and poverty are inextricably linked. Poor people are frequently unable to pay for housing, food, childcare, health care, and education. Difficult choices must be made when limited resources cover only some of these necessities. Often it is housing, which absorbs a high proportion of income that must be dropped. If you are poor, you are essentially an illness, an accident, or a paycheck away from living on the streets.

According to the United States Census Bureau, the national poverty rate in 2016 was 12.7%. There were 40.6 million people in poverty. While the poverty rate has been slowly declining since 2014, a couple of factors account for continuing poverty:

Lack of Employment Opportunities - With unemployment rates remaining high, jobs are hard to find in the current economy. Even if people can find work, this does not automatically provide an escape from poverty.

Decline in Available Public Assistance - The declining value and availability of public assistance is another source of increasing poverty and homelessness and many families leaving welfare struggle to get medical care, food, and housing as a result of loss of benefits, low wages, and unstable employment. Additionally, most states have not replaced the old welfare system with an alternative that enables families and individuals to obtain above-poverty employment and to sustain themselves when work is not available or possible.

Other major factors, which can contribute to homelessness, include:

Lack of Affordable Health Care - For families and individuals struggling to pay the rent, a serious illness or disability can start a downward spiral into homelessness, beginning with a lost job, depletion of savings to pay for care, and eventual eviction.

Domestic Violence - Battered women who live in poverty are often forced to choose between abusive relationships and homelessness. In addition, 50% of the cities surveyed by the U.S. Conference of Mayors identified domestic violence as a primary cause of homelessness (U.S. Conference of Mayors, 2005).

Mental Illness - Approximately 16% of the single adult homeless population suffers from some form of severe and persistent mental illness (U.S. Conference of Mayors, 2005).

Addiction - The relationship between addiction and homelessness is complex and controversial. Many people who are addicted to alcohol and drugs never become homeless, but people who are poor and addicted are clearly at increased risk of homelessness.

There are three types of homelessness - chronic, transitional, and episodic - which can be defined as follows:

Chronic Homelessness

Persons most like the stereotyped profile of the "skid-row" homeless, who are likely to be entrenched in the shelter system and for whom shelters are more like long-term housing rather than an emergency arrangement. These individuals are likely to be older, and consist of the "hard-core unemployed", often suffering from disabilities and substance abuse problems. Yet such persons represent a far smaller proportion of the population compared to the transitionally homeless.

Transitional Homelessness

Transitionally homeless individuals generally enter the shelter system for only one stay and for a short period. Such persons are likely to be younger, are probably recent members of the precariously housed population and have become homeless because of some catastrophic event, and have been forced to spend a short time in a homeless shelter before making a transition into more stable housing. Over time, transitionally homeless individuals will account for the majority of persons experiencing homelessness given their higher rate of turnover.

Episodic Homelessness

Those who frequently shuttle in and out of homelessness are known as episodically homeless. They are most likely to be young, but unlike those in transitional homelessness, episodically homeless individuals often are chronically unemployed and experience medical, mental health, and substance abuse problems.

Who Experiences Homelessness?

Persons living in poverty are most at risk of becoming homeless, and demographic groups who are more likely to experience poverty are also more likely to experience homelessness. Yet because of methodological and financial constraints, most studies are limited to counting persons who are in shelters or on the street. While the Census Bureau has taken a series of innovations to better incorporate the homeless population, these procedures continue to undercount this group by failing to visit many locations with homeless populations. Additionally, different governmental agencies often present different estimates/counts, making the figures on homelessness inconclusive.

Housing and Urban Development's Point-in-Time Count, 2016:

HUD found 549,928 individuals to be homeless on a single night in January 2016. Most homeless persons (65%) are individuals while 35% of homeless persons are in family households.

The number of families experiencing homelessness has increased significantly from past years. For example, in 2013 only 15% of homeless persons were in family households.

31% of all homeless people were youths under the age of 24.

Close to 40,000 veterans were homeless on a single night in January 2016. 66% were residing in shelters or transitional housing programs, while 33% were without shelter.

The number of those in homeless shelters or transitional housing was split almost equally between people in families (47%) and individuals (53%).

Five states, California (22%), New York (16%), Florida (6%), Texas (4%), and Washington (4%), accounted for more than half of the homeless population in the United States in 2016.

Where Do People Experience Homelessness?

Homelessness is often assumed to be an urban phenomenon because homeless people are more numerous, more geographically concentrated, and more visible in urban areas. However, people experience the same difficulties associated with homelessness and housing distress in America's small towns and rural areas as they do in urban areas.

In urban areas, estimates commonly rely on counts of persons using services. However, by this measure, homeless persons in rural areas are likely substantially under-counted due to the lack of rural service sites, the difficulty capturing persons who do not use homeless services, the limited number of researchers working in rural communities, and the minimal incentive for rural providers to collect data on their clients.
Rural homelessness, like urban homelessness, is the result of poverty and a lack of affordable housing, and research has shown:

The odds of being poor are between 1.2 to 2.3-times higher for people in non-metropolitan areas than in metropolitan areas

1 in 5 non-metro counties is classified as a 'high poverty' county (having a poverty rate of 20% or higher), while only 1 in 20 metro counties are defined as such

Homeless people in rural areas are more likely to be white, female, married, currently working, homeless for the first time, and homeless for a shorter period of time

Fact Sheets and Publications

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Homelessness in America - National Coalition for the Homeless

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Read below for some basic facts about homelessness. For more information, check out these resources: Further Issues that can lead to homelessness, or that face specific populations of people experiencing homelessness. NCH Reports and Publications on topics ranging from Criminalization to Homeless Counts. Archives of historical NCH Reports and resources collected by NCH relating to [...]

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https://en.wikipedia.org/wiki/Public_opinion_on_gun_control_in_the_United_States#:~:text=It%20found%20that%2064%25%20of,%25)%20and%20Republicans%20(49%25).

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https://en.wikipedia.org/wiki/Public_opinion_on_gun_control_in_the_United_States#:~:text=It%20found%20that%2064%25%20of,%25)%20and%20Republicans%20(49%25).

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https://www.npr.org/sections/goatsandsoda/2021/03/24/980838151/gun-violence-deaths-how-the-u-s-compares-to-the-rest-of-the-world

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It's a common conversation these days: One person says, "Black lives matter." Then another responds, "No, all lives matter."

It's also a complete misunderstanding of what the phrase "black lives matter" means. The person on the receiving end interprets the phrase as "black lives matter more than any other lives."

But the point of Black Lives Matter isn't to suggest that black lives should be or are more important than all other lives. Instead, it's simply pointing out that black people's lives are relatively undervalued in the US - and more likely to be ended by police - and the country needs to recognize that inequity to bring an end to it.

To this end, a better way to understand Black Lives Matter is by looking at its driving phrase as "black lives matter, too." So all lives do matter, obviously, but it's one subset of lives in particular that's currently undervalued in America.

But if that isn't good enough, here are nine other ways the response "all lives matter" has been rebuked.

1) "All houses matter"

2) A Reddit user's explanation

3) "All plates matter"

4) "There are other diseases too"

5) "I too have felt loss"

6) A Unitarian Universalist minister's explanation to a church member

Taken from the Unitarian Universalist Association's website:

Of course all lives matter. Central to Unitarian Universalism is the affirmation of the inherent worth and dignity of every person. Sadly, our society has a long history of treating some people as less valuable than others. Study after study has confirmed that in equivalent situations, African Americans and Latinos are treated with deadly force far more often than White people, and authorities held less accountable. Unfortunately, racial bias continues to exist even when it is no longer conscious-this too is confirmed by multiple studies. A lack of accountability in the use of force combined with unconscious bias is too often a deadly combination - and one that could place police officers, as well as the public, in great danger.

To say that Black lives matter is not to say that other lives do not; indeed, it is quite the reverse-it is to recognize that all lives do matter, and to acknowledge that African Americans are often targeted unfairly (witness the number of African Americans accosted daily for no reason other than walking through a White neighborhood-including some, like young Trayvon Martin, who lost their lives) and that our society is not yet so advanced as to have become truly color blind. This means that many people of goodwill face the hard task of recognizing that these societal ills continue to exist, and that White privilege continues to exist, even though we wish it didn't and would not have asked for it. I certainly agree that no loving God would judge anyone by skin color.

As a White man, I have never been followed by security in a department store, or been stopped by police for driving through a neighborhood in which I didn't live. My African American friends have, almost to a person, had these experiences. Some have been through incidents that were far worse. I owe it to the ideal that we share, the ideal that all lives matter, to take their experiences seriously and listen to what they are saying. To deny the truth of these experiences because they make me uncomfortable would be to place my comfort above the safety of others, and I cannot do that.

I very much appreciate you writing to me, and am glad that we share the goal of coming to a day when people will not be judged, consciously or unconsciously, on the basis of their race. I believe that day is possible, too, but that it will take a great deal of work to get there. That work begins by listening to one another, and listening especially to the voices of those who have the least power in society. If nothing else is clear from the past few weeks, it is painfully evident that a great many people do not believe that they are treated fairly. Healing begins by listening to those voices and stories.

7) A simple video explainer

8) A law professor's response to a student

Taken from the law professor's much longer letter to the student:

9) "If all lives matter ... prove it!"

If all lives matter... SHOW US!!! Prove it! Show us our bodies hold the same value. There is no excuse for the slaughter. None.
- Gabrielle Union (@itsgabrielleu) July 7, 2016

Watch: Why recording the police is so important
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Why you should stop saying "all lives matter," explained in 9 different ways

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It's a common conversation these days: One person says, "Black lives matter." Then another responds, "No, all lives matter." It's also a complete misunderstanding of what the phrase "black lives...

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https://www.nbcnews.com/news/us-news/compare-gun-violence-2021-n1265201

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The recent Black Lives Matter protests peaked on June 6, when half a million people turned out in nearly 550 places across the United States. That was a single day in more than a month of protests that still continue to today.

Four recent polls - including one released this week by Civis Analytics, a data science firm that works with businesses and Democratic campaigns - suggest that about 15 million to 26 million people in the United States have participated in demonstrations over the death of George Floyd and others in recent weeks.

These figures would make the recent protests the largest movement in the country's history, according to interviews with scholars and crowd-counting experts.

"I've never seen self-reports of protest participation that high for a specific issue over such a short period," said Neal Caren, associate professor at the University of North Carolina at Chapel Hill, who studies social movements in the United States.

While it's possible that more people said they protested than actually did, even if only half told the truth, the surveys suggest more than seven million people participated in recent demonstrations.

The Women's March of 2017 had a turnout of about three million to five million people on a single day, but that was a highly organized event. Collectively, the recent Black Lives Matter protests - more organic in nature - appear to have far surpassed those numbers, according to polls.

"Really, it's hard to overstate the scale of this movement," said Deva Woodly, an associate professor of politics at the New School.

Professor Woodly said that the civil rights marches in the 1960s were considerably smaller in number. "If we added up all those protests during that period, we're talking about hundreds of thousands of people, but not millions," she said.

Even protests to unseat government leadership or for independence typically succeed when they involve 3.5 percent of the population at their peak, according to a review of international protests by Erica Chenoweth, a professor at Harvard Kennedy School who co-directs the CrowdCounting Consortium, which collects data on crowd sizes of political protests.

Why this movement is different

Precise turnout at protests is difficult to count and has led to some famous disputes. An amalgam of estimates from organizers, the police and local news reports often make up the official total.

But tallies by teams of crowd counters are revealing numbers of extraordinary scale. On June 6, for example, at least 50,000 people turned out in Philadelphia, 20,000 in Chicago's Union Park and up to 10,000 on the Golden Gate Bridge, according to estimates by Edwin Chow, an associate professor at Texas State University, and researchers at the Crowd Counting Consortium.

Across the United States, there have been more than 4,700 demonstrations, or an average of 140 per day, since the first protests began in Minneapolis on May 26, according to a Times analysis. Turnout has ranged from dozens to tens of thousands in about 2,500 small towns and large cities.

Source: Crowd Counting Consortium

"The geographic spread of protest is a really important characteristic and helps signal the depth and breadth of a movement's support," said Kenneth Andrews, a sociology professor at the University of North Carolina at Chapel Hill.

One of the reasons there have been protests in so many places in the United States is the backing of organizations like Black Lives Matter. While the group isn't necessarily directing each protest, it provides materials, guidance and a framework for new activists, Professor Woodly said. Those activists are taking to social media to quickly share protest details to a wide audience.

Black Lives Matter has been around since 2013, but there's been a big shift in public opinion about the movement as well as broader support for recent protests. A deluge of public support from organizations like the N.F.L. and NASCAR for Black Lives Matter may have also encouraged supporters who typically would sit on the sidelines to get involved.

The protests may also be benefitting from a country that is more conditioned to protesting. The adversarial stance that the Trump administration has taken on issues like guns, climate change and immigration has led to more protests than under any other presidency since the Cold War.

According to a poll from The Washington Post and the Kaiser Family Foundation, one in five Americans said that they had participated in a protest since the start of the Trump administration, and 19 percent said they were new to protesting.

Who is protesting

More than 40 percent of counties in the United States - at least 1,360 - have had a protest. Unlike with past Black Lives Matter protests, nearly 95 percent of counties that had a protest recently are majority white, and nearly three-quarters of the counties are more than 75 percent white.

"Without gainsaying the reality and significance of generalized white support for the movement in the early 1960s, the number of whites who were active in a sustained way in the struggle were comparatively few, and certainly nothing like the percentages we have seen taking part in recent weeks," said Douglas McAdam, an emeritus professor at Stanford University who studies social movements.

According to the Civis Analytics poll, the movement appears to have attracted protesters who are younger and wealthier. The age group with the largest share of protesters was people under 35 and the income group with the largest share of protesters was those earning more than $150,000.

Half of those who said they protested said that this was their first time getting involved with a form of activism or demonstration. A majority said that they watched a video of police violence toward protesters or the Black community within the last year. And of those people, half said that it made them more supportive of the Black Lives Matter movement.

The protests are colliding with another watershed moment: the country's most devastating pandemic in modern history.

"With being home and not being able to do as much, that might be amplifying something that is already sort of critical, something that's already a powerful catalyst, and that is the video," said Daniel Q. Gillion, a professor at the University of Pennsylvania who has written several books on protests and politics.

"If you aren't moved by the George Floyd video, you have nothing in you," he said. "And that catalyst can now be amplified by the fact that individuals probably have more time to engage in protest activity."

Besides the spike in demonstrations on Juneteeth, the number of protests has fallen considerably over the last two weeks according to the Crowd Counting Consortium.

But the amount of change that the protests have been able to produce in such a short period of time is significant. In Minneapolis, the City Council pledged to dismantle its police department. In New York, lawmakers repealed a law that kept police disciplinary records secret. Cities and states across the country passed new laws banning chokeholds. Mississippi lawmakers voted to retire their state flag, which prominently includes a Confederate battle emblem.

"It looks, for all the world, like these protests are achieving what very few do: setting in motion a period of significant, sustained, and widespread social, political change," Professor McAdam said. "We appear to be experiencing a social change tipping point - that is as rare in society as it is potentially consequential."

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Black Lives Matter May Be the Largest Movement in U.S. History

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The recent Black Lives Matter protests peaked on June 6, when half a million people turned out in nearly 550 places across the United States. That was a single day in more than a month of protests that still continue to today.