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The world, not just the UN, is waking up to the power of faith-based organizations (FBOs). How can Islam, and other faiths, contribute to solutions to sustainability and mitigate climate change risks?

Odeh Al-Jayyousi, Professor and head of innovation at Arabian Gulf University in Bahrain, scholar in sustainable innovation and a member of UN Global Scientific Advisory Panel, for UN Environment's Global Environment Outlook 6 ( GEO6), argues that Islamic worldview represents a unique model for a transition to sustainable development by focusing on justice, degrowth and harmony between human and nature.

He commented that Islam views the environmental challenges as an indicator for a moral and ethical crisis. Looking at the creation of human, Earth, and cosmos as signs of the Creator ( Kitab Manthoor) is a key in Islamic values.

Prof. Al-Jayyousi elaborated that Islamic worldview defines a good life ( Hayat Tayebah) living lightly on Earth ( Zohd) and caring for both people and nature. Islamic discourse offers a sense of hope and optimism about the possibility of attaining harmony between human and nature. Earth will find a balance if humans rethink their lifestyles and mindsets as stated in the Quran:
Corruption has appeared in both land and sea
Because of what people's own hands have brought
So that they may taste something of what they have done
So that hopefully they will turn back
Qur'an 30: 41
Professor Al-Jayyousi calls to revive the holistic view of Islam which is founded on the notion of harmony and "natural state" ( fitra) and in respecting balance ( mizan) and proportion ( mikdar) in the systems of the universe. These notions provide an ethical dimension and a mandate for all humans to respect nature and all forms of life.

Hence, the overcoming environmental crisis and mitigating the impact of climate change, from an Islamic perspective is underpinned by defining the role of humans as trustees and stewards ( khalifah). This balance has been disturbed because to human choices which result in overconsumption, overexploitation and overuse of resources.

Photo by Reuters

Islamic values call to save integrity and to protect the diversity of all forms of life. Professor Al-Jayyousi commented that the ecological crisis is linked to human ethics and values. Human actions are responsible for the global ecological crisis. "Reflecting on the main environmental problems, such as the destruction of natural habitats, loss of biodiversity, climate change, and erosion of soil, we see that all are triggered by human greed and ignorance. Human responsibility is to save and protect livelihood and ecosystem services to ensure a sustainable civilization learning from and reflecting on the fate of past civilizations", said Professor Al-Jayyousi.

He cited a verse from the Holy Book, Quran, "Every living thing is in a state of worship". He commented that when one hurts a bird or a plant, he/she is silencing a community of worshippers. To celebrate the symphony of life, all humans need to celebrate and protect biological and cultural diversity.

Islamic worldview calls to make a transition to a sustainable society and economy by adopting responsible development and respecting sustainability principles. This change requires a shift in norms and practices. Religion can become a powerful part of the solution if humans embody a holistic spiritual view towards mankind, earth and cosmos.

In 2015 in Istanbul, the Muslim world in its Islamic declaration for climate change set the framework for an ethical code of conduct to build a low-emission climate resilient future.

Al-Jayyousi aspires to see a new Islamic discourse that emphasizes and links faith, reason and empathy to ensure an ecological insight ( Baseera). He calls to rethink educational systems that neglected the beauty and majesty of nature and the cosmos.

"The extinction of species around us which are simply communities like us ( Ummam Amthalokom) may extend to humankind unless we change our worldviews and development models", warns Prof. Al-Jayyousi. He calls to revive the concept of Green Endowment Fund ( Waqf) to support a transition to sustainable economy by promoting innovation ( ijtihad) inspired by nature and culture.

He proposed a conceptual model with three domains to address climate change and sustainability:

Green activism (Jihad)

Green innovation (Ijtihad)

Green lifestyle (Zohd).

He refers to this as a Green JIZ model, which represents an Islamic response to climate change embodying the concept of de-growth.

"Conflict and poor governance are putting the Middle East and North Africa at jeopardy" points out Prof. Al-Jayyousi. He calls for a sustainable region that is founded on human and environmental justice. An optimist, Prof. Al-Jayyousi is inspired by prophet Mohammed saying " If it is the Last day of life and you have a small plant, make sure you plant it".
About the Author:
Professor Odeh Al-Jayyousi is the head of Innovation and Technology Management at Arabian Gulf University, Bahrain. He published a book on "Islam and sustainable development", UK, (2012) and a book on Integral Innovation, 2017, UK. He is a member of UN GEO6- Scientific Advisory Panel.
E-mail:odjayousi[at]gmail.com

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How Islam can represent a model for environmental stewardship

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The world, not just the UN, is waking up to the power of faith-based organizations (FBOs). How can Islam, and other faiths, contribute to solutions to sustainability and mitigate climate change risks?

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Climate Change: Vital Signs of the Planet

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The rate of change since the mid-20th century is unprecedented over millennia.

Earth's climate has changed throughout history. Just in the last 800,000 years, there have been eight cycles of ice ages and warmer periods, with the end of the last ice age about 11,700 years ago marking the beginning of the modern climate era - and of human civilization. Most of these climate changes are attributed to very small variations in Earth's orbit that change the amount of solar energy our planet receives.

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.) Find out more about ice cores (external site).

The current warming trend is different because it is clearly the result of human activities since the mid-1800s, and is proceeding at a rate not seen over many recent millennia. It is undeniable that human activities have produced the atmospheric gases that have trapped more of the Sun's energy in the Earth system. This extra energy has warmed the atmosphere, ocean, and land, and widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred.

Do scientists agree on climate change?

Yes, the vast majority of actively publishing climate scientists - 97 percent - agree that humans are causing global warming and climate change.

detailed answer

Earth-orbiting satellites and new technologies have helped scientists see the big picture, collecting many different types of information about our planet and its climate all over the world. These data, collected over many years, reveal the signs and patterns of a changing climate.

Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th century. Many of the science instruments NASA uses to study our climate focus on how these gases affect the movement of infrared radiation through the atmosphere. From the measured impacts of increases in these gases, there is no question that increased greenhouse gas levels warm Earth in response.

"Scientific evidence for warming of the climate system is unequivocal."

- Intergovernmental Panel on Climate Change

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth's climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. Carbon dioxide from human activities is increasing about 250 times faster than it did from natural sources after the last Ice Age.

References

References
Header image shows clouds imitating mountains as the sun sets after midnight as seen from Denali's backcountry Unit 13 on June 14, 2019. Credit: NPS/Emily Mesner

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Climate Change Evidence: How Do We Know?

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Vital Signs of the Planet: Global Climate Change and Global Warming. How do we know it's happening? Here's the evidence.

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reveal topic

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A totally dried up farmer's watering hole on a farm near Shepperton, Victoria © Global Warming Images / WWF

Impacts of global warming

Keywords

biodiversity

climate change

Our climate is determined by patterns of temperature, wind, atmospheric pressure, humidity and rain over a long period of time. There are different climates around the world, such as tropical, dry and moderate. As a large country, Australia has a variety of climates.

The climate of an area determines its seasons and when they come and go. This, in turn, affects the type of plants that grow and which animals survive. The species and places we love depend on intricate ecosystems, and even small changes to the climate can disrupt the delicate balance of nature.

As humans, every aspect of our life is reliant on the natural environment. This includes the food we eat, the air we breathe, the water we drink, the clothes we wear and the products that are made and sold to create jobs and drive the economy.

A healthy and stable climate is our most precious natural resource.

What changes to the climate are humans causing through global warming?

Global warming, caused by greenhouse gas pollution, is causing immediate and direct changes to the planet.

The Earth's temperature had already warmed by 1°C compared to pre-industrial levels. This temperature rise may appear small, but small rises in temperature translate into big changes for the world's climate. This is because the amount of extra energy needed to increase the world's temperature, even by a little, is vast. This extra energy is like force-feeding the global climate system.

* Oceans are warming and acidifying:

The oceans have absorbed most of extra heat and carbon dioxide (CO ₂) so far - more than the air - making the seas both warmer and more acidic. Warming waters are bleaching coral reefs and driving stronger storms. Rising ocean acidity threatens shellfish, including the tiny crustaceans without which marine food chains would collapse.

Sadly, the poorest and most vulnerable nations, and the people who have contributed least to the problem, will be among the hardest hit by global warming. Some of the countries most at risk include our neighbours in the Pacific and Southeast Asia, including Kiribati, Tuvalu, Vietnam and the Philippines.

How is global warming affecting life in Australia?

* Ecosystems:
Global warming stresses ecosystems through temperature rises, water shortages, increased fire threats, drought, weed and pest invasions, intense storm damage and salt invasion, just to name a few. Some of Australia's great natural icons, such as the Great Barrier Reef, are already threatened.

* Species:
One in six species is at risk of extinction because of climate change. To survive, plants, animals and birds confronted with climate change have two options: move or adapt. With the speed of climate change we are experiencing already, it's often not possible for a species to adapt quickly enough to keep up with its changing environment. And with the amount of habitat destruction, moving is becoming increasingly difficult.

Read more on food and farming here.

Within Australia, the effects of global warming vary from region to region.
The impacts of global warming are already being felt across all areas of Australian life, and these will continue to worsen if we do not act now to limit global warming to 1.5°C.

Click here to see how your world could change as global temperatures rise.

If you have any questions about your donation, please do not hesitate to contact our friendly Supporter Services team either by email: enquiries@wwf.org.au or call 1800 032 551

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A totally dried up farmer's watering hole on a farm near Shepperton, Victoria © Global Warming Images / WWF Keywords biodiversity climate change Our climate is determined by patterns of temperature, wind, atmospheric pressure, humidity and rain over a long period of time. There are different climates around the world, such as tropical, dry and moderate.

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Climate Change: Vital Signs of the Planet

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Key Takeaway:

Earth's global average surface temperature in 2020 statistically tied with 2016 as the hottest year on record, continuing a long-term warming trend due to human activities.

This graph shows the change in global surface temperature compared to the long-term average from 1951 to 1980. The year 2020 statistically tied with 2016 for the hottest year on record since recordkeeping began in 1880 (source: NASA/GISS). NASA's analyses generally match independent analyses prepared by National Oceanic and Atmospheric Administration (NOAA) and other institutions.

The animation on the right shows the change in global surface temperatures. Dark blue shows areas cooler than average. Dark red shows areas warmer than average. Short-term variations are smoothed out using a 5-year running average to make trends more visible in this map.

The data shown are the latest available, updated annually.

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Global Surface Temperature | NASA Global Climate Change

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A graph and an animated time series showing the change in global surface temperature relative to 1951-1980 average temperatures. The year 2020 ties with 2016 as the warmest on record.

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analysis data chart 1

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Climate Change: Vital Signs of the Planet

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Earth's 2016 surface temperatures were the warmest since modern recordkeeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA).

Globally-averaged temperatures in 2016 were 1.78 degrees Fahrenheit (0.99 degrees Celsius) warmer than the mid-20th century mean. This makes 2016 the third year in a row to set a new record for global average surface temperatures.

The 2016 temperatures continue a long-term warming trend, according to analyses by scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. NOAA scientists concur with the finding that 2016 was the warmest year on record based on separate, independent analyses of the data.

This color-coded map displays a progression of changing global surface temperatures anomalies from 1880 through 2016. The final frame represents global temperature anomalies averaged from 2012 through 2016 in degrees Celsius. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio. Data provided by Robert B. Schmunk (NASA/GSFC GISS).

Because weather station locations and measurement practices change over time, there are uncertainties in the interpretation of specific year-to-year global mean temperature differences. However, even taking this into account, NASA estimates 2016 was the warmest year with greater than 95 percent certainty.

"2016 is remarkably the third record year in a row in this series," said GISS Director Gavin Schmidt. "We don't expect record years every year, but the ongoing long-term warming trend is clear."

The planet's average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere.

Most of the warming occurred in the past 35 years, with 16 of the 17 warmest years on record occurring since 2001. Not only was 2016 the warmest year on record, but eight of the 12 months that make up the year - from January through September, with the exception of June - were the warmest on record for those respective months. October, November, and December of 2016 were the second warmest of those months on record - in all three cases, behind records set in 2015.

Phenomena such as El Niño or La Niña, which warm or cool the upper tropical Pacific Ocean and cause corresponding variations in global wind and weather patterns, contribute to short-term variations in global average temperature. A warming El Niño event was in effect for most of 2015 and the first third of 2016. Researchers estimate the direct impact of the natural El Niño warming in the tropical Pacific increased the annual global temperature anomaly for 2016 by 0.2 degrees Fahrenheit (0.12 degrees Celsius).

Weather dynamics often affect regional temperatures, so not every region on Earth experienced record average temperatures last year. For example, both NASA and NOAA found the 2016 annual mean temperature for the contiguous 48 United States was the second warmest on record. In contrast, the Arctic experienced its warmest year ever, consistent with record low sea ice found in that region for most of the year.

The planet's long-term warming trend is seen in this chart of every year's annual temperature cycle from 1880 to the present, compared to the average temperature from 1880 to 2015. Record warm years are listed in the column on the right. Credit: NASA/Earth Observatory.Joshua Stevens.

NASA's analyses incorporate surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations. These raw measurements are analyzed using an algorithm that considers the varied spacing of temperature stations around the globe and urban heating effects that could skew the conclusions. The result of these calculations is an estimate of the global average temperature difference from a baseline period of 1951 to 1980.

NOAA scientists used much of the same raw temperature data, but with a different baseline period, and different methods to analyze Earth's polar regions and global temperatures.

GISS is a laboratory within the Earth Sciences Division of NASA's Goddard Space Flight Center in Greenbelt, Maryland. The laboratory is affiliated with Columbia University's Earth Institute and School of Engineering and Applied Science in New York.

The full 2016 surface temperature data set and the complete methodology used to make the temperature calculation are available at:
http://data.giss.nasa.gov/gistemp
Media contacts

Sean Potter
Headquarters, Washington
202-358-1536
sean.potter@nasa.gov

Michael Cabbage / Leslie McCarthy
Goddard Institute for Space Studies, New York
212-678-5516 / 212-678-5507
mcabbage@nasa.gov / leslie.m.mccarthy@nasa.gov

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NASA's Goddard Institute for Space Studies

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NASA, NOAA data show 2016 warmest year on record globally - Climate Change: Vital Signs of the Planet

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Earth's 2016 surface temperatures were the warmest since modern recordkeeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA). Globally-averaged temperatures in 2016 were 1.78 degrees Fahrenheit (0.99 degrees Celsius) warmer than the mid-20th century mean.

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Climate Change: Vital Signs of the Planet

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Arctic sea ice reaches its minimum extent (the area in which satellite sensors show individual pixels to be at least 15% covered in ice) each September. September Arctic sea ice is now shrinking at a rate of 12.2% per decade, compared to its average extent during the period from 1981 to 2010. This graph shows the size of the Arctic sea ice each September since satellite observations started in 1979. The monthly value shown is the average of daily observations across the month of September during each year and is measured from satellites.

The animated map below shows the minimum size of the Arctic sea ice measured each year since 1979, based on satellite observations. The 2012 sea ice extent is the lowest in the satellite record.

Sea ice extent is one of three key sea ice metrics. Other measurements include:

The data shown are the latest available, updated annually.
Learn more: With Thick Ice Gone, Arctic Sea Ice Changes More Slowly

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Arctic Sea Ice Minimum | NASA Global Climate Change

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Vital Signs of the Planet: Global Climate Change and Global Warming. Current news and data streams about global warming and climate change from NASA.

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analysis of data chart 1

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The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change Earth's energy balance and climate. Many other theories of climate change were advanced, involving forces from volcanism to solar variation. In the 1960s, the evidence for the warming effect of carbon dioxide gas became increasingly convincing. Some scientists also pointed out that human activities that generated atmospheric aerosols (e.g., "pollution") could have cooling effects as well.

During the 1970s, scientific opinion increasingly favored the warming viewpoint. By the 1990s, as the result of improving the fidelity of computer models and observational work confirming the Milankovitch theory of the ice ages, a consensus position formed: greenhouse gases were deeply involved in most climate changes and human-caused emissions were bringing discernible global warming. Since the 1990s, scientific research on climate change has included multiple disciplines and has expanded. Research has expanded our understanding of causal relations, links with historic data, and abilities to measure and model climate change. Research during this period has been summarized in the Assessment Reports by the Intergovernmental Panel on Climate Change.

Climate change, broadly interpreted, is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or in the distribution of weather around the average conditions (such as more or fewer extreme weather events). Climate change is caused by factors that include oceanic processes (such as oceanic circulation), biotic processes (e.g., plants), variations in solar radiation received by Earth, plate tectonics and volcanic eruptions, and human-induced alterations of the natural world. This last effect is currently causing global warming, and "climate change" is often used to describe human-specific impacts.

From ancient times, people suspected that the climate of a region could change over the course of centuries. For example, Theophrastus, a pupil of Ancient Greek philosopher Aristotle in the 4th century BC, told how the draining of marshes had made a particular locality more susceptible to freezing, and speculated that lands became warmer when the clearing of forests exposed them to sunlight. In the 1st century BC, Roman writer and architect Vitruvius wrote about climate in relation to housing architecture and how to choose locations for cities. Renaissance European and later scholars saw that deforestation, irrigation, and grazing had altered the lands around the Mediterranean since ancient times; they thought it plausible that these human interventions had affected the local weather. In his book published in 1088, Northern Song dynasty Chinese scholar and statesman Shen Kuo promoted the theory of gradual climate change over centuries of time once ancient petrified bamboos were found to be preserved underground in the dry climate zone and arid northern region of Yanzhou, now modern day Yan'an, Shaanxi province, far from the warmer, wetter climate areas of China where bamboos typically grow.

The 18th and 19th-century conversion of Eastern North America from forest to croplands brought obvious change within a human lifetime. From the early 19th century, many believed the transformation was altering the region's climate-probably for the better. When farmers in America, dubbed "sodbusters", took over the Great Plains, they held that " rain follows the plow." Other experts disagreed, and some argued that deforestation caused rapid rainwater run-off and flooding, and could even result in reduced rainfall. European academics, convinced of the superiority of their civilization, said that the Orientals of the Ancient Near East had heedlessly converted their once lush lands into impoverished deserts.

Meanwhile, national weather agencies had begun to compile masses of reliable observations of temperature, rainfall, and the like. When these figures were analyzed, they showed many rises and dips, but no steady long-term change. By the end of the 19th century, scientific opinion had turned decisively against any belief in a human influence on climate. And whatever the regional effects, few imagined that humans could affect the climate of the planet as a whole.

From the mid-17th century, naturalists attempted to reconcile mechanical philosophy with theology, initially within a Biblical timescale. By the late 18th century, there was increasing acceptance of prehistoric epochs. Geologists found evidence of a succession of geological ages with climate changes. There were various competing theories about these changes; Buffon proposed that the Earth had begun as an incandescent globe and was very gradually cooling. James Hutton, whose ideas of cyclic change over huge periods were later dubbed uniformitarianism, was among those who found signs of past glacial activity in places too warm for glaciers in modern times.

In 1815 Jean-Pierre Perraudin described for the first time how glaciers might be responsible for the giant boulders seen in alpine valleys. As he hiked in the Val de Bagnes, he noticed giant granite rocks that were scattered around the narrow valley. He knew that it would take an exceptional force to move such large rocks. He also noticed how glaciers left stripes on the land and concluded that it was the ice that had carried the boulders down into the valleys.

His idea was initially met with disbelief. Jean de Charpentier wrote, "I found his hypothesis so extraordinary and even so extravagant that I considered it as not worth examining or even considering." Despite Charpentier's initial rejection, Perraudin eventually convinced Ignaz Venetz that it might be worth studying. Venetz convinced Charpentier, who in turn convinced the influential scientist Louis Agassiz that the glacial theory had merit.

Agassiz developed a theory of what he termed " Ice Age"-when glaciers covered Europe and much of North America. In 1837 Agassiz was the first to scientifically propose that the Earth had been subject to a past ice age. William Buckland had been a leading proponent in Britain of flood geology, later dubbed catastrophism, which accounted for erratic boulders and other "diluvium" as relics of the Biblical flood. This was strongly opposed by Charles Lyell's version of Hutton's uniformitarianism and was gradually abandoned by Buckland and other catastrophist geologists. A field trip to the Alps with Agassiz in October 1838 convinced Buckland that features in Britain had been caused by glaciation, and both he and Lyell strongly supported the ice age theory which became widely accepted by the 1870s.

Before the concept of ice ages was proposed, Joseph Fourier in 1824 reasoned based on physics that Earth's atmosphere kept the planet warmer than would be the case in a vacuum. Fourier recognized that the atmosphere transmitted visible light waves efficiently to the earth's surface. The earth then absorbed visible light and emitted infrared radiation in response, but the atmosphere did not transmit infrared efficiently, which therefore increased surface temperatures. He also suspected that human activities could influence the radiation balance and Earth's climate, although he focused primarily on land-use changes. In an 1827 paper, Fourier stated,

The establishment and progress of human societies, the action of natural forces, can notably change, and in vast regions, the state of the surface, the distribution of water and the great movements of the air. Such effects are able to make to vary, in the course of many centuries, the average degree of heat; because the analytic expressions contain coefficients relating to the state of the surface and which greatly influence the temperature.

Fourier's work built on previous discoveries: in 1681 Edme Mariotte noted that glass, though transparent to sunlight, obstructs radiant heat. Around 1774 Horace Bénédict de Saussure showed that non-luminous warm objects emit infrared heat, and used a glass-topped insulated box to trap and measure heat from sunlight.

The physicist Claude Pouillet proposed in 1838 that water vapor and carbon dioxide might trap infrared and warm the atmosphere, but there was still no experimental evidence of these gases absorbing heat from thermal radiation.

The warming effect of electromagnetic radiation on different gases was examined in 1856 by Eunice Newton Foote, who described her experiments using glass tubes exposed to sunlight. The warming effect of the sun was greater for compressed air than for an evacuated tube and greater for moist air than dry air. "Thirdly, the highest effect of the sun's rays I have found to be in carbonic acid gas." (carbon dioxide) She continued: "An atmosphere of that gas would give to our earth a high temperature; and if, as some suppose, at one period of its history, the air had mixed with it a larger proportion than at present, an increased temperature from its action, as well as from an increased weight, must have necessarily resulted." Her work was presented by Prof. Joseph Henry at the American Association for the Advancement of Science meeting in August 1856 and described as a brief note written by then journalist David Ames Wells; her paper was published later that year in the American Journal of Science and Arts. Few noticed the paper and it was only rediscovered in the 21st century,

John Tyndall took Fourier's work one step further in 1859 when he built an apparatus to investigate the absorption of infrared radiation in different gases. He found that water vapor, hydrocarbons like methane (CH ₄), and carbon dioxide (CO ₂) strongly block the radiation. He understood that without these gases the planet would rapidly freeze.

Some scientists suggested that ice ages and other great climate changes were due to changes in the amount of gases emitted in volcanism. But that was only one of many possible causes. Another obvious possibility was solar variation. Shifts in ocean currents also might explain many climate changes. For changes over millions of years, the raising and lowering of mountain ranges would change patterns of both winds and ocean currents. Or perhaps the climate of a continent had not changed at all, but it had grown warmer or cooler because of polar wander (the North Pole shifting to where the Equator had been or the like). There were dozens of theories.

For example, in the mid-19th century, James Croll published calculations of how the gravitational pulls of the Sun, Moon, and planets subtly affect the Earth's motion and orientation. The inclination of the Earth's axis and the shape of its orbit around the Sun oscillate gently in cycles lasting tens of thousands of years. During some periods the Northern Hemisphere would get slightly less sunlight during the winter than it would get during other centuries. Snow would accumulate, reflecting sunlight and leading to a self-sustaining ice age. Most scientists, however, found Croll's ideas-and every other theory of climate change-unconvincing.

By the late 1890s, Samuel Pierpoint Langley along with Frank W. Very had attempted to determine the surface temperature of the Moon by measuring infrared radiation leaving the Moon and reaching the Earth. The angle of the Moon in the sky when a scientist took a measurement determined how much CO ₂ and water vapor the Moon's radiation had to pass through to reach the Earth's surface, resulting in weaker measurements when the Moon was low in the sky. This result was unsurprising given that scientists had known about infrared radiation absorption for decades.

In 1896 Svante Arrhenius used Langley's observations of increased infrared absorption where Moon rays pass through the atmosphere at a low angle, encountering more carbon dioxide (CO ₂), to estimate an atmospheric cooling effect from a future decrease of CO ₂. He realized that the cooler atmosphere would hold less water vapor (another greenhouse gas) and calculated the additional cooling effect. He also realized the cooling would increase snow and ice cover at high latitudes, making the planet reflect more sunlight and thus further cool down, as James Croll had hypothesized. Overall Arrhenius calculated that cutting CO ₂ in half would suffice to produce an ice age. He further calculated that a doubling of atmospheric CO ₂ would give a total warming of 5-6 degrees Celsius.

Further, Arrhenius' colleague Arvid Högbom, who was quoted in length in Arrhenius' 1896 study On the Influence of Carbonic Acid in the Air upon the Temperature of the Earth had been attempting to quantify natural sources of emissions of CO ₂ for purposes of understanding the global carbon cycle. Högbom found that estimated carbon production from industrial sources in the 1890s (mainly coal burning) was comparable with the natural sources. Arrhenius saw that this human emission of carbon would eventually lead to a warming energy imbalance. However, because of the relatively low rate of CO ₂ production in 1896, Arrhenius thought the warming would take thousands of years, and he expected it would be beneficial to humanity.

In 1899 Thomas Chrowder Chamberlin developed at length the idea that climate changes could result from changes in the concentration of atmospheric carbon dioxide. Chamberlin wrote in his 1899 book, An Attempt to Frame a Working Hypothesis of the Cause of Glacial Periods on an Atmospheric Basis:

Previous advocacy of an atmospheric hypothesis, - The general doctrine that the glacial periods may have been due to a change in the atmospheric content of carbon dioxide is not new. It was urged by Tyndall a half-century ago and has been urged by others since. Recently it has been very effectively advocated by Dr. Arrhenius, who has taken a great step in advance of his predecessors in reducing his conclusions to definite quantitative terms deduced from observational data. [..] The functions of carbon dioxide. - By the investigations of Tyndall, Lecher and Pretner, Keller, Roentgen, and Arrhenius, it has been shown that the carbon dioxide and water vapor of the atmosphere have remarkable power of absorbing and temporarily retaining heat rays, while the oxygen, nitrogen, and argon of the atmosphere possess this power in a feeble degree only. It follows that the effect of the carbon dioxide and water vapor is to blanket the earth with a thermally absorbent envelope. [..] The general results assignable to a greatly increased or a greatly reduced quantity of atmospheric carbon dioxide and water may be summarized as follows:

a. An increase, by causing a larger absorption of the sun's radiant energy, raises the average temperature, while a reduction lowers it. The estimate of Dr. Arrhenius, based upon an elaborate mathematical discussion of the observations of Professor Langley, is that an increase of the carbon dioxide to the amount of two or three times the present content would elevate the average temperature 8° or 9 °C. and would bring on a mild climate analogous to that which prevailed in the Middle Tertiary age. On the other hand, a reduction of the quantity of carbon dioxide in the atmosphere to an amount ranging from 55 to 62 per cent, of the present content, would reduce the average temperature 4 or 5 C, which would bring on a glaciation comparable to that of the Pleistocene period.

b. A second effect of increase and decrease in the amount of atmospheric carbon dioxide is the equalization, on the one hand, of surface temperatures, or their differentiation on the other. The temperature of the surface of the earth varies with latitude, altitude, the distribution of land and water, day and night, the seasons, and some other elements that may here be neglected. It is postulated that an increase in the thermal absorption of the atmosphere equalizes the temperature, and tends to eliminate the variations attendant on these contingencies. Conversely, a reduction of thermal atmospheric absorption tends to intensify all of these variations. A secondary effect of intensification of differences of temperature is an increase of atmospheric movements in the effort to restore equilibrium. Increased atmospheric movements, which are necessarily convectional, carry the warmer air to the surface of the atmosphere, and facilitate the discharge of the heat and thus intensify the primary effect. [..]

In the case of the outgoing rays, which are absorbed in much larger proportions than the incoming rays because they are more largely long-wave rays, the tables of Arrhenius show that the absorption is augmented by increase of carbonic acid in greater proportions in high latitudes than in low; for example, the increase of temperature for three times the present content of carbonic acid is 21.5 per cent, greater between 60° and 70° N. latitude than at the equator.

It now becomes necessary to assign agencies capable of removing carbon dioxide from the atmosphere at a rate sufficiently above the normal rate of supply, at certain times, to produce glaciation; and on the other hand, capable of restoring it to the atmosphere at certain other times in sufficient amounts to produce mild climates.

When the temperature is rising after a glacial episode, dissociation is promoted, and the ocean gives forth its carbon dioxide at an increased rate, and thereby assists in accelerating the amelioration of climate.

A study of the life of the geological periods seems to indicate that there were very notable fluctuations in the total mass of living matter. To be sure there was a reciprocal relation between the life of the land and that of the sea, so that when the latter was extended upon the continental platforms and greatly augmented, the former was contracted, but notwithstanding this it seems clear that the sum of life activity fluctuated notably during the ages. It is believed that on the whole it was greatest at the periods of sea extension and mild climates, and least at the times of disruption and climatic intensification. This factor then acted antithetically to the carbonic acid freeing previously noted, and, so far as it went, tended to offset its effects.

In periods of sea extension and of land reduction (base-level periods in particular), the habitat of shallow water lime-secreting life is concurrently extended, giving to the agencies that set carbon dioxide free accelerated activity, which is further aided by the consequent rising temperature which reduces the absorptive power of the ocean and increases dissociation. At the same time, the area of the land being diminished, a low consumption of carbon dioxide both in original decomposition of the silicates and in the solution of the limestones and dolomites obtains.

Thus the reciprocating agencies again conjoin, but now to increase the carbon dioxide of the air. These are the great and essential factors. They are modified by several subordinate agencies already mentioned, but the quantitative effect of these is thought to be quite insufficient to prevent very notable fluctuations in the atmospheric constitution.

As a result, it is postulated that geological history has been accentuated by an alternation of climatic episodes embracing, on the one hand, periods of mild, equable, moist climate nearly uniform for the whole globe; and on the other, periods when there were extremes of aridity and precipitation, and of heat and cold; these last denoted by deposits of salt and gypsum, of subaerial conglomerates, of red sandstones and shales, of arkose deposits, and occasionally by glaciation in low latitudes.

The term " greenhouse effect" for this warming was introduced by John Henry Poynting in 1909, in a commentary discussing the effect of the atmosphere on the temperature of the Earth and Mars.

Arrhenius's calculations were disputed and subsumed into a larger debate over whether atmospheric changes had caused the ice ages. Experimental attempts to measure infrared absorption in the laboratory seemed to show little differences resulted from increasing CO ₂ levels, and also found significant overlap between absorption by CO ₂ and absorption by water vapor, all of which suggested that increasing carbon dioxide emissions would have little climatic effect. These early experiments were later found to be insufficiently accurate, given the instrumentation of the time. Many scientists also thought that the oceans would quickly absorb any excess carbon dioxide.

Other theories of the causes of climate change fared no better. The principal advances were in observational paleoclimatology, as scientists in various fields of geology worked out methods to reveal ancient climates. In 1929, Wilmot H. Bradley found that annual varves of clay laid down in lake beds showed climate cycles. Andrew Ellicott Douglass saw strong indications of climate change in tree rings. Noting that the rings were thinner in dry years, he reported climate effects from solar variations, particularly in connection with the 17th-century dearth of sunspots (the Maunder Minimum) noticed previously by William Herschel and others. Other scientists, however, found good reason to doubt that tree rings could reveal anything beyond random regional variations. The value of tree rings for climate study was not solidly established until the 1960s.

Through the 1930s the most persistent advocate of a solar-climate connection was astrophysicist Charles Greeley Abbot. By the early 1920s, he had concluded that the solar "constant" was misnamed: his observations showed large variations, which he connected with sunspots passing across the face of the Sun. He and a few others pursued the topic into the 1960s, convinced that sunspot variations were a main cause of climate change. Other scientists were skeptical. Nevertheless, attempts to connect the solar cycle with climate cycles were popular in the 1920s and 1930s. Respected scientists announced correlations that they insisted were reliable enough to make predictions. Sooner or later, every prediction failed, and the subject fell into disrepute.

Meanwhile, Milutin Milankovitch, building on James Croll's theory, improved the tedious calculations of the varying distances and angles of the Sun's radiation as the Sun and Moon gradually perturbed the Earth's orbit. Some observations of varves (layers seen in the mud covering the bottom of lakes) matched the prediction of a Milankovitch cycle lasting about 21,000 years. However, most geologists dismissed the astronomical theory. For they could not fit Milankovitch's timing to the accepted sequence, which had only four ice ages, all of them much longer than 21,000 years.

In 1938 Guy Stewart Callendar attempted to revive Arrhenius's greenhouse-effect theory. Callendar presented evidence that both temperature and the CO ₂ level in the atmosphere had been rising over the past half-century, and he argued that newer spectroscopic measurements showed that the gas was effective in absorbing infrared in the atmosphere. Nevertheless, most scientific opinion continued to dispute or ignore the theory.

Better spectrography in the 1950s showed that CO ₂ and water vapor absorption lines did not overlap completely. Climatologists also realized that little water vapor was present in the upper atmosphere. Both developments showed that the CO ₂ greenhouse effect would not be overwhelmed by water vapor.

In 1955 Hans Suess's carbon-14 isotope analysis showed that CO ₂ released from fossil fuels was not immediately absorbed by the ocean. In 1957, better understanding of ocean chemistry led Roger Revelle to a realization that the ocean surface layer had limited ability to absorb carbon dioxide, also predicting the rise in levels of CO ₂ and later being proven by Charles David Keeling. By the late 1950s, more scientists were arguing that carbon dioxide emissions could be a problem, with some projecting in 1959 that CO ₂ would rise 25% by the year 2000, with potentially "radical" effects on climate. In the centennial of the American oil industry in 1959, organized by the American Petroleum Institute and the Columbia Graduate School of Business, Edward Teller said "It has been calculated that a temperature rise corresponding to a 10 per cent increase in carbon dioxide will be sufficient to melt the icecap and submerge New York. ... At present the carbon dioxide in the atmosphere has risen by 2 per cent over normal. By 1970, it will be perhaps 4 per cent, by 1980, 8 per cent, by 1990, 16 per cent if we keep on with our exponential rise in the use of purely conventional fuels.". In 1960 Charles David Keeling demonstrated that the level of CO ₂ in the atmosphere was in fact rising. Concern mounted year by year along with the rise of the " Keeling Curve" of atmospheric CO ₂.

Another clue to the nature of climate change came in the mid-1960s from analysis of deep-sea cores by Cesare Emiliani and analysis of ancient corals by Wallace Broecker and collaborators. Rather than four long ice ages, they found a large number of shorter ones in a regular sequence. It appeared that the timing of ice ages was set by the small orbital shifts of the Milankovitch cycles. While the matter remained controversial, some began to suggest that the climate system is sensitive to small changes and can readily be flipped from a stable state into a different one.

Scientists meanwhile began using computers to develop more sophisticated versions of Arrhenius's calculations. In 1967, taking advantage of the ability of digital computers to integrate absorption curves numerically, Syukuro Manabe and Richard Wetherald made the first detailed calculation of the greenhouse effect incorporating convection (the "Manabe-Wetherald one-dimensional radiative-convective model"). They found that, in the absence of unknown feedbacks such as changes in clouds, a doubling of carbon dioxide from the current level would result in approximately 2 °C increase in global temperature. For this, and related work, Manabe was awarded a share of the 2021 Nobel Prize in Physics.

By the 1960s, aerosol pollution ("smog") had become a serious local problem in many cities, and some scientists began to consider whether the cooling effect of particulate pollution could affect global temperatures. Scientists were unsure whether the cooling effect of particulate pollution or warming effect of greenhouse gas emissions would predominate, but regardless, began to suspect that human emissions could be disruptive to climate in the 21st century if not sooner. In his 1968 book The Population Bomb, Paul R. Ehrlich wrote, "the greenhouse effect is being enhanced now by the greatly increased level of carbon dioxide... [this] is being countered by low-level clouds generated by contrails, dust, and other contaminants... At the moment we cannot predict what the overall climatic results will be of our using the atmosphere as a garbage dump."

Efforts to establish a global temperature record that began in 1938 culminated in 1963, when J. Murray Mitchell presented one of the first up-to-date temperature reconstructions. His study involved data from over 200 weather stations, collected by the World Weather Records, which was used to calculate latitudinal average temperature. In his presentation, Murray showed that, beginning in 1880, global temperatures increased steadily until 1940. After that, a multi-decade cooling trend emerged. Murray's work contributed to the overall acceptance of a possible global cooling trend.

In 1965, the landmark report "Restoring the Quality of Our Environment" by U.S. President Lyndon B. Johnson's Science Advisory Committee warned of the harmful effects of fossil fuel emissions:

The part that remains in the atmosphere may have a significant effect on climate; carbon dioxide is nearly transparent to visible light, but it is a strong absorber and back radiator of infrared radiation, particularly in the wave lengths from 12 to 18 microns; consequently, an increase of atmospheric carbon dioxide could act, much like the glass in a greenhouse, to raise the temperature of the lower air.

The committee used the recently available global temperature reconstructions and carbon dioxide data from Charles David Keeling and colleagues to reach their conclusions. They declared the rise of atmospheric carbon dioxide levels to be the direct result of fossil fuel burning. The committee concluded that human activities were sufficiently large to have significant, global impact-beyond the area the activities take place. "Man is unwittingly conducting a vast geophysical experiment", the committee wrote.

Nobel Prize winner Glenn T. Seaborg, Chairperson of the United States Atomic Energy Commission warned of the climate crisis in 1966: "At the rate we are currently adding carbon dioxide to our atmosphere (six billion tons a year), within the next few decades the heat balance of the atmosphere could be altered enough to produce marked changes in the climate--changes which we might have no means of controlling even if by that time we have made great advances in our programs of weather modification."

A 1968 study by the Stanford Research Institute for the American Petroleum Institute noted:

If the earth's temperature increases significantly, a number of events might be expected to occur, including the melting of the Antarctic ice cap, a rise in sea levels, warming of the oceans, and an increase in photosynthesis.... Revelle makes the point that man is now engaged in a vast geophysical experiment with his environment, the earth. Significant temperature changes are almost certain to occur by the year 2000 and these could bring about climatic changes.

In 1969, NATO was the first candidate to deal with climate change on an international level. It was planned then to establish a hub of research and initiatives of the organization in the civil area, dealing with environmental topics as acid rain and the greenhouse effect. The suggestion of US President Richard Nixon was not very successful with the administration of German Chancellor Kurt Georg Kiesinger. But the topics and the preparation work done on the NATO proposal by the German authorities gained international momentum, (see e.g. the Stockholm United Nations Conference on the Human Environment 1970) as the government of Willy Brandt started to apply them on the civil sphere instead.[clarification needed ]

Also in 1969, Mikhail Budyko published a theory on the ice-albedo feedback, a foundational element of what is today known as Arctic amplification. The same year a similar model was published by William D. Sellers. Both studies attracted significant attention, since they hinted at the possibility for a runaway positive feedback within the global climate system.

In the early 1970s, evidence that aerosols were increasing worldwide and that the global temperature series showed cooling encouraged Reid Bryson and some others to warn of the possibility of severe cooling. The questions and concerns put forth by Bryson and others launched a new wave of research into the factors of such global cooling. Meanwhile, the new evidence that the timing of ice ages was set by predictable orbital cycles suggested that the climate would gradually cool, over thousands of years. Several scientific panels from this time period concluded that more research was needed to determine whether warming or cooling was likely, indicating that the trend in the scientific literature had not yet become a consensus. For the century ahead, however, a survey of the scientific literature from 1965 to 1979 found 7 articles predicting cooling and 44 predicting warming (many other articles on climate made no prediction); the warming articles were cited much more often in subsequent scientific literature. Research into warming and greenhouse gases held the greater emphasis, with nearly six times more studies predicting warming than predicting cooling, suggesting concern among scientists was largely over warming as they turned their attention toward the greenhouse effect.

John Sawyer published the study Man-made Carbon Dioxide and the "Greenhouse" Effect in 1972. He summarized the knowledge of the science at the time, the anthropogenic attribution of the carbon dioxide greenhouse gas, distribution and exponential rise, findings which still hold today. Additionally he accurately predicted the rate of global warming for the period between 1972 and 2000.

The increase of 25% CO2 expected by the end of the century therefore corresponds to an increase of 0.6 °C in the world temperature - an amount somewhat greater than the climatic variation of recent centuries. - John Sawyer, 1972

The first satellite records compiled in the early 1970s showed snow and ice cover over the Northern Hemisphere to be increasing, prompting further scrutiny into the possibility of global cooling. J. Murray Mitchell updated his global temperature reconstruction in 1972, which continued to show cooling. However, scientists determined that the cooling observed by Mitchell was not a global phenomenon. Global averages were changing, largely in part due to unusually severe winters experienced by Asia and some parts of North America in 1972 and 1973, but these changes were mostly constrained to the Northern Hemisphere. In the Southern Hemisphere, the opposite trend was observed. The severe winters, however, pushed the issue of global cooling into the public eye.

The mainstream news media at the time exaggerated the warnings of the minority who expected imminent cooling. For example, in 1975, magazine published a story titled "The Cooling World" that warned of "ominous signs that the Earth's weather patterns have begun to change." The article drew on studies documenting the increasing snow and ice in regions of the Northern Hemisphere and concerns and claims by Reid Bryson that global cooling by aerosols would dominate carbon dioxide warming. The article continued by stating that evidence of global cooling was so strong that meteorologists were having "a hard time keeping up with it." On 23 October 2006, Newsweek issued an update stating that it had been "spectacularly wrong about the near-term future". Nevertheless, this article and others like it had long-lasting effects on public perception of climate science.

(within 60 years:) Because of the "greenhouse effect" of atmospheric CO2 the increased concentration will induce a global climatic warming of anywhere from 0.5 to 5 °C.
... The potential effect on the environment of a climatic fluctuation of such rapidity could be catastrophic and calls for an impact assessment of unprecedented importance and difficulty. A rapid climatic change may result in large scale crop failures at a time when an increased world population taxes agriculture to the limits of productivity.
... The urgency of the problem derives from our inability to shift rapidly to non-fossil fuel sources once the climatic effects become evident not long after the year 2000; ...

-Frank Press, 7 July 1977
Chief science adviser to U.S. President Carter

Such media coverage heralding the coming of a new ice age resulted in beliefs that this was the consensus among scientists, despite this is not being reflected by the scientific literature. As it became apparent that scientific opinion was in favor of global warming, the public began to express doubt over how trustworthy the science was. The argument that scientists were wrong about global cooling, so therefore may be wrong about global warming has been called "the "Ice Age Fallacy" by TIME author Bryan Walsh.

In the first two "Reports for the Club of Rome" in 1972 and 1974, the anthropogenic climate changes by CO ₂ increase as well as by waste heat were mentioned. About the latter John Holdren wrote in a study cited in the 1st report, "... that global thermal pollution is hardly our most immediate environmental threat. It could prove to be the most inexorable, however, if we are fortunate enough to evade all the rest". Simple global-scale estimates that recently have been actualized and confirmed by more refined model calculations show noticeable contributions from waste heat to global warming after the year 2100, if its growth rates are not strongly reduced (below the averaged 2% p.a. which occurred since 1973).

Evidence for warming accumulated. By 1975, Manabe and Wetherald had developed a three-dimensional global climate model that gave a roughly accurate representation of the current climate. Doubling CO ₂ in the model's atmosphere gave a roughly 2 °C rise in global temperature. Several other kinds of computer models gave similar results: it was impossible to make a model that gave something resembling the actual climate and not have the temperature rise when the CO ₂ concentration was increased.

In a separate development, an analysis of deep-sea cores published in 1976 by Nicholas Shackleton and colleagues showed that the dominating influence on ice age timing came from a 100,000-year Milankovitch orbital change. This was unexpected, since the change in sunlight in that cycle was slight. The result emphasized that the climate system is driven by feedbacks, and thus is strongly susceptible to small changes in conditions.

A 1977 memo (see quote box) from President Carter's chief science adviser Frank Press warned of the possibility of catastrophic climate change. However, other issues-such as known harms to health from pollutants, and avoiding energy dependence on other nations-seemed more pressing and immediate. Energy Secretary James Schlesinger advised that "the policy implications of this issue are still too uncertain to warrant Presidential involvement and policy initiatives", and the fossil fuel industry began sowing doubt about climate science.

The 1979 World Climate Conference (12 to 23 February) of the World Meteorological Organization concluded "it appears plausible that an increased amount of carbon dioxide in the atmosphere can contribute to a gradual warming of the lower atmosphere, especially at higher latitudes. ... It is possible that some effects on a regional and global scale may be detectable before the end of this century and become significant before the middle of the next century."

In July 1979 the United States National Research Council published a report, concluding (in part):

When it is assumed that the CO ₂ content of the atmosphere is doubled and statistical thermal equilibrium is achieved, the more realistic of the modeling efforts predict a global surface warming of between 2 °C and 3.5 °C, with greater increases at high latitudes. ... we have tried but have been unable to find any overlooked or underestimated physical effects that could reduce the currently estimated global warmings due to a doubling of atmospheric CO ₂ to negligible proportions or reverse them altogether.

By the early 1980s, the slight cooling trend from 1945 to 1975 had stopped. Aerosol pollution had decreased in many areas due to environmental legislation and changes in fuel use, and it became clear that the cooling effect from aerosols was not going to increase substantially while carbon dioxide levels were progressively increasing.

Hansen and others published the 1981 study Climate impact of increasing atmospheric carbon dioxide, and noted:

It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980s. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.

In 1982, Greenland ice cores drilled by Hans Oeschger, Willi Dansgaard, and collaborators revealed dramatic temperature oscillations in the space of a century in the distant past. The most prominent of the changes in their record corresponded to the violent Younger Dryas climate oscillation seen in shifts in types of pollen in lake beds all over Europe. Evidently drastic climate changes were possible within a human lifetime.

In 1973 James Lovelock speculated that chlorofluorocarbons (CFCs) could have a global warming effect. In 1975 V. Ramanathan found that a CFC molecule could be 10,000 times more effective in absorbing infrared radiation than a carbon dioxide molecule, making CFCs potentially important despite their very low concentrations in the atmosphere. While most early work on CFCs focused on their role in ozone depletion, by 1985 Ramanathan and others showed that CFCs together with methane and other trace gases could have nearly as important a climate effect as increases in CO ₂. In other words, global warming would arrive twice as fast as had been expected.

In 1985 a joint UNEP/WMO/ICSU Conference on the "Assessment of the Role of Carbon Dioxide and Other Greenhouse Gases in Climate Variations and Associated Impacts" concluded that greenhouse gases "are expected" to cause significant warming in the next century and that some warming is inevitable.

Meanwhile, ice cores drilled by a Franco-Soviet team at the Vostok Station in Antarctica showed that CO ₂ and temperature had gone up and down together in wide swings through past ice ages. This confirmed the CO ₂-temperature relationship in a manner entirely independent of computer climate models, strongly reinforcing the emerging scientific consensus. The findings also pointed to powerful biological and geochemical feedbacks.

In June 1988, James E. Hansen made one of the first assessments that human-caused warming had already measurably affected global climate. Shortly after, a " World Conference on the Changing Atmosphere: Implications for Global Security" gathered hundreds of scientists and others in Toronto. They concluded that the changes in the atmosphere due to human pollution "represent a major threat to international security and are already having harmful consequences over many parts of the globe," and declared that by 2005 the world would be well-advised to push its emissions some 20% below the 1988 level.

The 1980s saw important breakthroughs with regard to global environmental challenges. Ozone depletion was mitigated by the Vienna Convention (1985) and the Montreal Protocol (1987). Acid rain was mainly regulated on national and regional levels.

In 1988 the WMO established the Intergovernmental Panel on Climate Change with the support of the UNEP. The IPCC continues its work through the present day, and issues a series of Assessment Reports and supplemental reports that describe the state of scientific understanding at the time each report is prepared. Scientific developments during this period are summarized about once every five to six years in the IPCC Assessment Reports which were published in 1990 ( First Assessment Report), 1995 ( Second Assessment Report), 2001 ( Third Assessment Report), 2007 ( Fourth Assessment Report), 2013/2014 ( Fifth Assessment Report). and 2021 Sixth Assessment Report The 2001 report was the first to state positively that the observed global temperature increase was "likely" to be due to human activities. The conclusion was influenced especially by the so-called hockey stick graph showing an abrupt historical temperature rise simultaneous with the rise of greenhouse gas emissions, and by observations of changes in ocean heat content that had a "signature" matching the pattern that computer models calculated for the effect of greenhouse warming. By the time of the 2021 report, scientists had much additional evidence. Above all, measurements of paleotemperatures from several eras in the distant past, and the record of temperature change since the mid 19th century, could be matched against measurements of CO ₂ levels to provide independent confirmation of supercomputer model calculations.

These developments depended crucially on huge globe-spanning observation programs. Since the 1990s research into historical and modern climate change expanded rapidly. International coordination was provided by the World Climate Research Programme (established in 1980) and was increasingly oriented around providing input to the IPCC reports. Measurement networks such as the Global Ocean Observing System, Integrated Carbon Observation System, and NASA's Earth Observing System enabled monitoring of the causes and effects of ongoing change. Research also broadened, linking many fields such as Earth sciences, behavioral sciences, economics, and security.

Dessler, Andrew E. and Edward A. Parson, eds. The science and politics of global climate change: A guide to the debate (Cambridge University Press, 2019). excerpt

Edwards, Paul N. "History of climate modeling." Wiley Interdisciplinary Reviews: Climate Change 2.1 (2011): 128-139. online

Edwards P. N. A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming (MIT Press; 2010).

Weart S. R. The Discovery of Global Warming (2nd ed 2008) excerpt
Weart S. R. The discovery of global warming: a hypertext history of how scientists came to (partly) understand what people are doing to cause climate change (American Institute of Physics, College Park; revised annually since 2003) online

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History of climate change science - Wikipedia

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The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change Earth's energy balance and climate.

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analysis of data for chart 2

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On September 16, Arctic sea ice appeared to have reached its minimum extent for the year of 3.41 million square kilometers (1.32 million square miles). This is the lowest seasonal minimum extent in the satellite record since 1979 and reinforces the long-term downward trend in Arctic ice extent. The sea ice extent will now begin its seasonal increase through autumn and winter.
Please note that this is a preliminary announcement. Changing winds could still push ice floes together, reducing ice extent further. NSIDC scientists will release a full analysis of the melt season in early October, once monthly data are available for September.
Overview of conditions

On September 16, 2012 sea ice extent dropped to 3.41 million square kilometers (1.32 million square miles). This appears to have been the lowest extent of the year. In response to the setting sun and falling temperatures, ice extent will now climb through autumn and winter. However, a shift in wind patterns or a period of late season melt could still push the ice extent lower. The minimum extent was reached three days later than the 1979 to 2000 average minimum date of September 13.

This year's minimum was 760,000 square kilometers (293,000 square miles) below the previous record minimum extent in the satellite record, which occurred on September 18, 2007. This is an area about the size of the state of Texas. The September 2012 minimum was in turn 3.29 million square kilometers (1.27 million square miles) below the 1979 to 2000 average minimum, representing an area nearly twice the size of the state of Alaska. This year's minimum is 18% below 2007 and 49% below the 1979 to 2000 average.

Overall there was a loss of 11.83 million square kilometers (4.57 million square miles) of ice since the maximum extent occurred on March 20, 2012, which is the largest summer ice extent loss in the satellite record, more than one million square kilometers greater than in any previous year.

Conditions in context

The six lowest seasonal minimum ice extents in the satellite record have all occurred in the last six years (2007 to 2012). In contrast to 2007, when climatic conditions (winds, clouds, air temperatures) favored summer ice loss, this year's conditions were not as extreme. Summer temperatures across the Arctic were warmer than average, but cooler than in 2007. The most notable event was a very strong storm centered over the central Arctic Ocean in early August. It is likely that the primary reason for the large loss of ice this summer is that the ice cover has continued to thin and become more dominated by seasonal ice. This thinner ice was more prone to be broken up and melted by weather events, such as the strong low pressure system just mentioned. The storm sped up the loss of the thin ice that appears to have been already on the verge of melting completely.

Varying distribution of ice in 2012 vs. 2007

The spatial pattern of ice extent at this year's seasonal minimum is different than that observed for 2007. This year the ice is more extensive in some parts of the central Arctic Ocean. However, the ice is less extensive this year compared to 2007 in the Beaufort Sea, the western Laptev Sea, the East Greenland Sea, and parts of the Canadian Archipelago. As mentioned in our previous post, the Northern Sea Route opened around mid August this year, compared to 2007 when a tongue of ice extended to the coast, blocking the route throughout the summer.

Previous minimum Arctic sea ice extents
Note that the dates and extents of the minimums have changed since we originally posted in 2007; see our Frequently Asked Questions for more information.

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Arctic sea ice extent settles at record seasonal minimum

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On September 16, Arctic sea ice appeared to have reached its minimum extent for the year of 3.41 million square kilometers (1.32 million square miles). This is the lowest seasonal minimum extent in the satellite record since 1979 and reinforces the long-term downward trend in Arctic ice extent.

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recommendation

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What can we help you find?

Climate change is affecting everyone everywhere. Extreme weather events are more frequent and intense, sea levels are rising and many species are being driven to extinction. The good news is, you are not alone! People, communities, cities, businesses, schools, faith groups and organizations are taking action to help fight climate change. What changes will you make? Here are the top 10 things you can do about climate change. Choose just one to start.

2. Use energy wisely - and save money

Canada is the top per-capita energy consumer in the world! By becoming more energy-efficient, you pollute less and save money.

Consider making some or all of these small changes. Together, they really add up.

A house with a furnace is like a car that idles all day. Reduce or eliminate fossil fuels from your home by swapping your furnace for a heat pump.

Replace your gas water heater with a heat pump water heater.

Install a programmable or smart thermostat.

Swap your gas stove for an induction stove, which will also lower indoor air pollution.

Replace your gas fireplace with an electric one.

Unplug computers, TVs and other electronics when you're not using them.

Wash clothes in cold water. Hang your clothes to dry when you can and use  wool dryer balls to shrink drying time when you can't

Look for the ENERGY STAR label when buying new appliances.

Repair improperly sealed doors and windows and upgrade your insulation. Winterize your home  to prevent heat from escaping. Try to keep it cool in the summer  without an air conditioner.

Change to ENERGY STAR-certified LED light bulbs.

Get a home or workplace energy audit to identify where you can save the most.

Get tips and resources to live sustainably

6. Invest in renewables and divest from fossil fuels

Even if you can't install solar panels or a wind turbine, you can still be a part of the clean-energy economy. Search online for local renewable energy co-ops to join. As a member, you'll own part of the co-op's renewable energy projects and receive a return on your investment. You can also speak to your financial adviser about clean energy and/or technology investments.

Let industry know you care about climate change by meeting with your bank or investment adviser to make sure your investments do not include fossil fuels. And make sure your workplace, pension fund, university or bank doesn't invest in fossil fuels. If they do, join or start a divestment campaign.

Learn more about why it's important to divest from damage and invest in a healthier future.

9. Mobilize for local climate action

"What our cities do individually and in unison to address climate change can set the agenda for communities and governments everywhere." C40 Cities

In Canada, municipalities have influence over about 50 per cent of our emissions. And with about 80 per cent of people living in Canada living in cities, it's important - even crucial - that we focus on their potential to help stop climate change.

Citizens like you, willing to work with progressive local government leaders, stand to make a huge difference. Your role as a citizen with your local government is powerful.

We have created a comprehensive online resource to help you work with your local government on climate action.
Explore the guide

10. Get politically active and vote

It's important to take action to reduce individual carbon footprints, but changing the larger system is the greatest opportunity to reduce emissions.

Vote for leaders at all levels of government who take climate change seriously. They should commit to set science-based targets to reduce harmful carbon emissions, implement clear plans to reach those targets, adapt to climate change and shift to a clean-energy economy.

Your vote matters. Make sure you are registered to vote and then get informed for all elections - not just the ones that get the most media attention. Candidates' positions on climate change vary widely, so research the parties, ask questions about climate change at town halls or debates and let all candidates know you are voting for the climate.

If you're too young to vote, encourage your class or school to join a Student Vote program, which provides opportunities to experience participation in the election process. Talk to people in your life who are eligible to vote about the importance of voting for climate action.

The first step is registering to vote.

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Top 10 things you can do about climate change

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People, communities, cities, businesses, schools and other organizations are taking action to help fight climate change.

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Rising sea levels. Raging storms. Searing heat. Ferocious fires. Severe drought. Punishing floods. The effects of climate change are already threatening our health, our communities, our economy, our security, and our children's future.

What can you do? A whole lot, as it turns out. Americans, on average, produce 21 tons of carbon a year, about four times the global average. Personal action is, of course, no substitute for meaningful government policies. We still must limit carbon pollution and aggressively move away from dirty fossil fuels toward cleaner power.

But it's important to remember the equally vital contributions that can be made by private citizens-which is to say, by you. "Change only happens when individuals take action," says clean energy advocate Aliya Haq. "There's no other way, if it doesn't start with people."

Here are a dozen easy, effective ways each one of us can make a difference.

1. Speak up!

What's the single biggest way you can make an impact on global climate change? "Talk to your friends and family, and make sure your representatives are making good decisions," Haq says. By voicing your concerns-via social media or, better yet, directly to your elected officials-you send a message that you care about the warming world. Encourage Congress to enact new laws that limit carbon emissions and require polluters to pay for the emissions they produce. "The main reason elected officials do anything difficult is because their constituents make them," Haq says. You can help protect public lands, stop offshore drilling, and more here.

2. Power your home with renewable energy.

Choose a utility company that generates at least half its power from wind or solar and has been certified by Green-e Energy, an organization that vets renewable energy options. If that isn't possible for you, take a look at your electric bill; many utilities now list other ways to support renewable sources on their monthly statements and websites.

3. Weatherize, weatherize, weatherize.

"Building heating and cooling are among the biggest uses of energy," Haq says. Indeed, heating and air-conditioning account for almost half of home energy use. You can make your space more energy efficient by sealing drafts and ensuring it's adequately insulated. You can also claim federal tax credits for many energy efficiency home improvements. To help you figure out where to start, you could also get a home energy audit, which some utilities offer free of charge. (Alternatively, you can hire a professional to come to your home and perform one; the Inflation Reduction Act offers a partial tax credit for this.) The EPA's Home Energy Yardstick gives you a simple assessment of your home's annual energy use compared with similar homes.

4. Invest in energy-efficient appliances.

Since they were first implemented nationally in 1987, efficiency standards for dozens of appliances and products have kept 2.3 billion tons of carbon dioxide out of the air. That's about the same amount as the annual carbon pollution coughed up by nearly 440 million cars. "Energy efficiency is the lowest-cost way to reduce emissions," Haq says. When shopping for refrigerators, washing machines, heat pump water heaters, and other appliances, look for the Energy Star label. It will tell you which are the most efficient. (There may also be rebates to earn from your purchase of Energy Star-certified products.)

And when you're ready to swap out your old machines, don't just put them on the curb: Recycling an old refrigerator through the EPA's Responsible Appliance Disposal Program can prevent an additional 10,000 pounds of carbon pollution because the global-warming pollutants in the refrigerants and foam would be properly captured rather than vented to the air.

5. Reduce water waste.

Saving water reduces carbon pollution, too. That's because it takes a lot of energy to pump, heat, and treat your water. So take shorter showers, turn off the tap while brushing your teeth, and switch to WaterSense-labeled fixtures and appliances. The EPA estimates that if just one out of every 100 American homes were retrofitted with water-efficient fixtures, about 100 million kilowatt-hours of electricity per year would be saved-avoiding 80,000 tons of global warming pollution.

6. Actually eat the food you buy-and compost what you can't.

Approximately 10 percent of U.S. energy use goes into growing, processing, packaging, and shipping food-about 40 percent of which winds up in the landfill. "If you're wasting less food, you're likely cutting down on energy consumption," Haq says. As for the scraps you can't eat or the leftovers you don't get to, collect them in a compost bin instead of sending them to the landfill where they release methane. Recycling food and other organic waste into compost provides a range of environmental benefits, including improving soil health, reducing greenhouse gas emissions, recycling nutrients, and mitigating the impact of droughts.

7. Buy better bulbs.

LED light bulbs use one-sixth the amount of energy to deliver the same amount of light as conventional incandescents and last at least 10 times longer. They're also cheaper in the long run: A 10-watt LED that replaces your traditional 60-watt bulb will save you $125 over the light bulb's life. And because the average American home has around 40 to 50 light bulbs, this is a simple swap that will reap huge rewards. If every household in the United States replaced just one incandescent with an Energy Star-labeled LED, we would prevent seven billion pounds of carbon pollution per year. That's equivalent to the emissions of about 648,000 cars.

8. Pull the plug(s).

Taken together, the outlets in your home are likely powering about 65 devices-an average load for a home in the United States. Audio and video devices, cordless vacuums and power tools, and other electronics use energy even when they're not charging. This "idle load" across all U.S. households adds up to the output of 50 large power plants in the country. So don't leave fully charged devices plugged into your home's outlets, unplug rarely used devices or plug them into power strips and timers, and adjust your computers and monitors to automatically power down to the lowest power mode when not in use.

9. Drive a fuel-efficient vehicle.

Gas-smart cars, such as hybrids and fully electric vehicles, save fuel and money. And once all cars and light trucks meet 2025's clean car standards, which means averaging 54.5 miles per gallon, they'll be a mainstay. For good reason: Relative to a national fleet of vehicles that averaged only 28.3 miles per gallon in 2011, Americans will spend $80 billion less at the pump each year and cut their automotive emissions by half. Before you buy a new set of wheels, compare fuel-economy performance here.

10. Maintain your ride.

If all Americans kept their tires properly inflated, we could save 1.2 billion gallons of gas each year. A simple tune-up can boost miles per gallon anywhere from 4 percent to 40 percent, and a new air filter can get you a 10 percent boost. Also, remove unnecessary accessories from your car roof. Roof racks and clamshell storage containers can reduce fuel efficiency by as much as 5 percent.

11. Rethink planes, trains, and automobiles.

Choosing to live in walkable smart-growth cities and towns with quality public transportation leads to less driving, less money spent on fuel, and less pollution in the air. Less frequent flying can make a big difference, too. "Air transport is a major source of climate pollution," Haq says. "If you can take a train instead, do that." If you must fly, consider purchasing carbon offsets to counterbalance the hefty carbon pollution associated with flying. But not all carbon offset companies are alike. Do your homework to find the best supplier.

12. Reduce, reuse, and recycle.

In the United States, the average person generates 4.5 pounds of trash every day. Fortunately, not all the items we discard end up in landfills; we recycle or compost more than one-third of our trash. In 2014 this saved carbon emissions equivalent to the yearly output of 38 million passenger cars. But we could be doing so much more. "Reduce should always be the number-one priority," says NRDC senior resource specialist Darby Hoover. And to reap the environmental benefits of "recyclable" goods, you must recycle according to the rules of your municipality, since systems vary widely by location. Search your municipality's sanitation department (or equivalent) webpage to learn exactly what you can place in the recycling bin, as counties and cities often differ in what they accept.
This story was originally published on April 20, 2022 and has been updated with new information and links.

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There are many ways to prevent global warming from becoming worse. Many nations have put laws into place to fight climate change -- here's what you can do.