# data[].attributes.attachment_link.readable_text
A hog farm in Vanceboro, N.C., is surrounded by floodwater in the aftermath of 2018's Hurricane Florence. (Alex Wroblewski/Bloomberg News)

Comment
Article
The smell of hog feces was overwhelming, Elsie Herring said. The breezes that wafted from the hog farm next to her mother's Duplin County, N.C., home carried hazardous gases: methane, ammonia, hydrogen sulfide.
10 steps you can take to lower your carbon footprint
"The odor is so offensive that we start gagging, we start coughing," she told a congressional committee in November 2019. Herring, who died last week, said she and other residents developed headaches, breathing problems and heart conditions from the fumes.

Now, a first-of-its-kind study shows that air pollution from Duplin County farms is linked to roughly 98 premature deaths per year, 89 of which are linked to emissions directly caused by hogs. Those losses are among more than 17,000 annual deaths attributable to pollution from farms across the United States, according to research published today in the Proceedings of the National Academy of Sciences.

Advertisement

Animal agriculture is the worst emitter, researchers say, responsible for 80 percent of deaths from pollution related to food production. Gases associated with manure and animal feed produce small, lung-irritating particles capable of drifting hundreds of miles. These emissions now account for more annual deaths than pollution from coal power plants. Yet while pollution from power plants, factories and vehicles is restricted under the Clean Air Act, there is less regulation of air quality around farms.

"The food system has really flown under the radar" as a source of deadly pollution, said University of Minnesota professor Jason Hill, the lead author of the new report. "But what we eat affects not just our own health, but the health of others. We're showing that directly."

Jim Monroe, a spokesman for the National Pork Producers Council, criticized the study as "highly suspect," saying it "irresponsibly draws conclusions based on modeling and estimates."

Advertisement

"U.S. pork producers have a strong track record of environmental stewardship," he wrote in an email, citing a 2019 study from Harper Consulting and Southern Utah University that found significant reductions in ammonia content from pig farms.

A spokesman for Smithfield Foods, which operates industrial hog operations in Duplin County, referred The Washington Post to a 2019 report in which the North Carolina Department of Environmental Quality said it did not find significant air-quality problems in the region.

Ethan Lane, vice president of government affairs for the National Cattlemen's Beef Association, also questioned the methodology of the study, which utilized relatively new air-quality models. "It appears to be based on faulty assumptions and riddled with data gaps," he said in a statement.

Advertisement

This is the first major report to link air-pollution deaths to specific food items, Hill said. While greenhouse gases cause the same amount of warming no matter where on the planet they're produced, the health effects of air pollution are dependent on atmospheric chemistry, local weather, and the size and health of communities living nearby. Only with advanced new air-quality models has it become possible to pinpoint the consequences of pollution produced hundreds of miles away.

"Agriculture is a tough industry" to monitor, said environmental scientist Maya Almaraz, who was not involved in the study. "They're already working at such thin margins, and really important to the economy. Regulations are not taken lightly in those systems."

But, she added, "we have to be working with those systems to protect the people who live in those communities."

Advertisement

Farm pollution is most dangerous when it occurs upwind of densely populated areas, Hill said. Most of the deaths in his analysis happened in California's Central Valley, eastern North Carolina and the Corn Belt of the Upper Midwest.

The most insidious kinds of air pollution are known as particulate matter (PM) 2.5 - tiny particles one-thirtieth the width of a human hair, which can become lodged in lungs or absorbed into the bloodstream. Exposure to PM 2.5 can lead to asthma and other breathing problems, and over the long term increases the risk of dying of heart disease, cancer and stroke.

These particles are directly produced when farmers till fields or burn crops before harvest. They can also come in the form of dust kicked up by livestock in large animal feeding operations.

This "primary" PM 2.5 is associated with about 4,800 premature deaths per year, the study found.

But "secondary" particulate matter, which is generated when emissions from farms interact with other gases in the atmosphere, is even more problematic. This is especially true for ammonia, a highly reactive molecule released by manure and fertilizer, which can combine with other pollutants such as nitrogen and sulfur compounds to create small, hazardous particles.

"Of all pollutants, ammonia is the one that has the greatest impact on mortality," Hill said. His analysis suggests that ammonia emissions contribute to about 12,400 deaths per year.

Advertisement

This is what makes pollution from animal agriculture so dangerous, Hill added. At many beef, pork and dairy facilities, animal waste is stored in massive "lagoons," such as the one near Herring's mother's home in Duplin County. There, the microbes that break down feces release huge amounts of ammonia. Many facilities spray nitrogen-rich liquid waste on nearby farm fields, another source of contamination.

Ammonia is also produced from over-application of fertilizer on such crops as corn. Because much of the nation's corn goes to animal feed, Hill counted those emissions toward animal agriculture's footprint.

All those emissions added up to make meat the biggest source of deadly emissions, Hill said. Per serving, the rate of air-pollution deaths linked to red meat was twice as high as that of eggs, three times as high as that of dairy, and at least 15 times as high as that of all fruits and vegetables.

Advertisement

"This type of research is extremely important," said Blakely Hildebrand, an attorney at the Southern Environmental Law Center who has fought emissions from North Carolina hog farms. "The lagoon system that has existed for decades harms people and harms the environment and it's time for a change."

Yet because ammonia is so reactive, it's difficult to detect unless huge amounts are released at once. When the North Carolina Department of Environmental Quality agreed to monitor air pollution in Duplin County as part of a settlement with Rural Empowerment Association for Community Help (REACH) and other civil rights groups, it found just five instances of elevated ammonia levels, none of which were high enough to trigger federal action. The program was discontinued after a year, when the department said it found no significant air-quality problems.

But the survey was criticized as inadequate because the environment department intentionally situated its monitoring stations far from hog farms. Almost all Duplin County residents live within three miles of at least one of these operations.

Advertisement

And the health disparities in Duplin County and places like it are substantial. A 2018 study by researchers at Duke University found that mortality rates in North Carolina communities with hog farms were 30 percent higher than in the rest of the state. California's San Joaquin Valley, another hot spot for ammonia pollution, has the highest rate of childhood asthma in the United States, according to the American Lung Association.

"You go through the central valley and it's just this thick layer of gray," said Almaraz, who is the program manager for the Working Lands Innovation Center at the University of California at Davis.

Although California has some of the country's strictest air-quality standards for cars and smokestacks, she said, "we're not really doing anything at a regulatory standpoint to decrease emissions coming from farms."

Advertisement

"But recognizing these sources really provides mitigation opportunities," she added. "Now that we know this is an important source, what can we do about it?"

Hill and his colleagues found that farmers could halve the number of air-pollution deaths from food production by changing their practices. Instead of leaving manure to decompose in lagoons, they could incorporate it into soil as fertilizer. Covering lagoons, separating urine from feces, and controlling the acidity and temperature of lagoons would also reduce ammonia emissions.

"We know the technology is there," said Devon Hall, an environmental justice advocate who co-founded REACH in Duplin County. "And we would hope that the industry would do the right thing."

Targeted fertilizer applications would reduce the amount of ammonia released into the air on croplands, Hill said. Reducing tillage and burning of waste and cutting emissions from equipment could also lead to small health gains.

But the greatest power to save lives lies with consumers, the scientists found. If Americans switched to a "flexitarian" diet, getting at least half their calories from fruits and vegetable and limiting animal protein to just a few meals per week, air-pollution mortality from agriculture would fall 68 percent.

That cultural shift would deliver a host of other benefits. Research suggests that reducing meat consumption could reduce global mortality by 6 to 10 percent - preventing hundreds of thousands of premature deaths.

Meat production is also the most resource-intensive form of agriculture. A whopping 30 percent of Earth's ice-free land mass is used for pasture for livestock, and red meat requires more water and carbon than any other food. If Earth's biggest beef eaters limited their intake to 1.5 hamburgers a week, they could avoid about 5.5 billion tons of greenhouse gas emissions per year - twice the annual emissions of India.

Discussions about dietary changes are always sensitive, Hill acknowledged. When Colorado Gov. Jared Polis (D) declared a "MeatOut" day in March, Republican state Sen. Barbara Kirkmeyer called it an attack against her county and the Colorado Cattlemen's Association called for people to flock to restaurants and order meat dishes.

But Hill hoped the study would give consumers one more thing to consider when they're putting food on their plates.

"It's one thing to eat a low-carbon diet," he said. "But it's another to say, 'Gosh, if I eat this delicious lentil dish instead of a hamburger, it might be better for my own health but also for other people.' "

# data[].attributes.attachment_link.title
Air pollution from farms leads to 17,900 U.S. deaths per year, study finds

# data[].attributes.attachment_link.description
CommentArticle The smell of hog feces was overwhelming, Elsie Herring said. The breezes that wafted from the hog farm next to her mother's Duplin County, N.C., home carried hazardous gases: methane, ammonia, hydrogen sulfide. 10 steps you can take to lower your carbon footprint ArrowRight "The odor is so offensive that we start gagging, we start coughing," she told a congressional committee in November 2019.

# data[].attributes.attachment_link.readable_text
Between 2010 and 2011, the U.S. population increased by 0.7 percent, after averaging 0.9 percent growth each year from 2000 through 2010. ¹ The United States added just 2.3 million people from 2010 to 2011, compared with 2.9 million from 2005 to 2006, just five years earlier. The decline in U.S. population growth is likely due to a confluence of factors: lower levels of immigration, population aging, and declining fertility rates.

A drop in net immigration to the United States is a key factor in the country's declining population growth rate. Around the turn of the millennium, the Census Bureau was estimating net international migration at about 1.4 million per year. By late in the decade, that annual number had been adjusted downward to less than 900,000. Between 2010 and 2011, net migration was estimated at around 700,000. The drop in immigration levels means that a smaller share of U.S. population growth is directly attributable to immigration, as opposed to natural increase (the excess of births over deaths). In the early 2000s, immigration accounted for roughly 40 percent of U.S. population growth, leaving 60 percent from natural increase. ² During the past few years, however, net international migration is estimated to have accounted for only 30 percent of the annual population growth.

The decline in immigration has been linked to job losses in construction, manufacturing, and other occupations that are often filled by recent immigrants, as well as stricter enforcement of immigration laws. Net immigration levels from Mexico are estimated to have reached zero in recent years as an equal number of people entering the United States from Mexico are now returning to their home country. ³

Slower Latino and Asian Population Growth

Because most immigrants to the United States arrive from Latin America or Asia, the decline in net international immigration has contributed to slower growth in the Latino and Asian American populations. Latinos and Asians remain the country's two fastest-growing minority groups, but their growth rates have dropped below the peaks reported just a few years ago.

Population growth for Latinos averaged 3.6 percent per year during the previous decade, but fell to just 2.5 percent between 2010 and 2011 (see Figure 1). There was a similar drop for Asian Americans during the same period, from 3.6 percent to 2.2 percent. ⁴ Although the rate of change fell for both groups, the number of Asians and Latinos is still increasing. And both groups are still growing faster than African Americans (1 percent) and non-Hispanic whites (0.1 percent).
Percent Annual Change in U.S. Population, by Racial/Ethnic Group
Source: U.S. Census Bureau, population estimates.

Population Aging

The recent decline in immigration has also accelerated population aging in the United States. Most immigrants are working-age adults, and many start families after they arrive in the U.S., creating an immigrant youth bulge. ⁵ Less immigration therefore reduces the potential number of young people in the population. But even if immigrant levels had held steady during the recession, the U.S. population would still be growing older as the large cohort of baby boomers starts to reach retirement age.

A decade ago, children under age 18 made up a significant component of annual population growth and exceeded the growth of those ages 65 and older (see Figure 2). But by 2011, these patterns had reversed: The number of people under age 18 declined by 190,000 between 2010 and 2011, while the number of elderly increased by 917,000. Growth in the number of working-age adults, including those in prime childbearing ages, is also down sharply.
Annual Change in U.S. Population, by Age Group
Source: U.S. Census Bureau, population estimates.

Because of its relatively young age structure, the United States still has a great deal of population momentum compared to many other developed countries. ⁶ But as more baby boomers enter retirement and there are fewer people of reproductive age, we could see further declines in the number of births, and the age structure of the United States could start to resemble that of Europe.

Declining Fertility Rates

U.S. fertility rates have also declined in recent years, reducing levels of natural increase in the population. There were an estimated 4 million births between 2010 and 2011, down from 4.2 million at the recent peak of U.S. population growth between 2005 and 2006. The total fertility rate (TFR) stood at 2.0 births per woman in 2009-down from 2.1 a few years ago-but preliminary data from the National Center for Health Statistics (NCHS) suggest that the TFR could drop below 2 births per woman in 2010.

Latinos currently account for more than one-fourth of all births in the United States. Yet the Latina general fertility rate (births per 1,000 Latinas ages 15 to 44) dropped from 102 in 2007 to 80 in 2010, according to preliminary NCHS estimates. This represents a significant decline for a group with historically high fertility rates-approaching 3 births per woman just a few years ago. If current trends continue, the Latina TFR could drop below 2.5 in the near future.

The U.S. population is currently projected to reach "majority minority" status (the point at which less than 50 percent of the population is non-Hispanic white) in 2042. However, a sustained drop in immigration levels and fertility rates would slow the pace of minority population growth. It's too soon to tell whether these are short-term trends resulting from the U.S. economic downturn, or whether they will continue in the future. But either way, these current trends represent a significant departure from developments over the past decade.

References

1. Population estimates are from the U.S. Census Bureau and are reported as of July 1 of each year.

2. Mary M. Kent and Mark Mather, "What Drives U.S. Population Growth?" Population Bulletin 57, no. 4 (2002), accessed on May 17, 2012.

3. Jeffrey Passel, D'Vera Cohn, and Ana Gonzalez-Barrera, "Net Migration from Mexico Falls to Zero-and Perhaps Less" (May 3, 2012), accessed on May 17, 2012.

4. Data are shown for the Asian alone population.

5. Mark Mather, "Children in Immigrant Families Chart New Path," PRB Reports on America (Washington, DC: Population Reference Bureau, 2009), accessed on May 17, 2012.

6. Mark Mather, Kelvin Pollard, and Linda A. Jacobsen, "First Results from the 2010 Census," PRB Reports on America (Washington DC: Population Reference Bureau, 2011), accessed on May 17, 2012.

# data[].attributes.attachment_link.title
What's Driving the Decline in U.S. Population Growth?

# data[].attributes.attachment_link.description
(2012) Between 2010 and 2011, the U.S. population increased by 0.7 percent, after averaging 0.9 percent growth each year from 2000 through 2010.1 The United States added just 2.3 million people from 2010 to 2011, compared with 2.9 million from 2005 to 2006, just five years earlier.

# data[].attributes.headline
Human Population Growth and Demographic Transition

# data[].attributes.subject
Human Population Growth and Demographic Transition

# data[].attributes.attachment_link.readable_text
Abstract

The world and most regions and countries are experiencing unprecedentedly rapid demographic change. The most obvious example of this change is the huge expansion of human numbers: four billion have been added since 1950. Projections for the next half century expect a highly divergent world, with stagnation or potential decline in parts of the developed world and continued rapid growth in the least developed regions. Other demographic processes are also undergoing extraordinary change: women's fertility has dropped rapidly and life expectancy has risen to new highs. Past trends in fertility and mortality have led to very young populations in high fertility countries in the developing world and to increasingly older populations in the developed world. Contemporary societies are now at very different stages of their demographic transitions. This paper summarizes key trends in population size, fertility and mortality, and age structures during these transitions. The focus is on the century from 1950 to 2050, which covers the period of most rapid global demographic transformation.

Keywords: population growth, demographic transition, fertility, mortality, age structure

1. Introduction

After centuries of very slow and uneven growth, the world population reached one billion in 1800. The modern expansion of human numbers started then, rising at a slow but more steady pace over the next 150 years to 2.5 billion in 1950. During the second half of the twentieth century, however, growth rates accelerated to historically unprecedented levels. As a result, world population more than doubled to 6.5 billion in 2005 (United Nations 1962, 1973, 2007). This population expansion is expected to continue for several more decades before peaking near 10 billion later in the twenty-first century. Around 2070, the world's population will be 10 times larger than in 1800.

The recent period of very rapid demographic change in most countries around the world is characteristic of the central phases of a secular process called the demographic transition. Over the course of this transition, declines in birth rates followed by declines in death rates bring about an era of rapid population growth. This transition usually accompanies the development process that transforms an agricultural society into an industrial one. Before the transition's onset, population growth (which equals the difference between the birth and death rate in the absence of migration) is near zero as high death rates more or less offset the high birth rates typical of agrarian societies before the industrial revolution. Population growth is again near zero after the completion of the transition as birth and death rates both reach low levels in the most developed societies. During the intervening transition period, rapid demographic change occurs, characterized by two distinct phases. During the first phase, the population growth rate rises as the death rate declines while the birth rate remains high. In the second phase, the growth rate declines (but remains positive) due to a decline in the birth rate. The entire transition typically takes more than a century to complete and ends with a much larger population size.

The plot of world population size over time in figure 1 (top solid line) shows the typical S-shaped pattern of estimated and projected population size over the course of the transition. Population growth accelerated for most of the twentieth century reaching the transition's midpoint in the 1980s and has recently begun to decelerate slightly. Today, we are still on the steepest part of this growth curve with additions to world population exceeding 75 million per year between 1971 and 2016.

Contemporary societies are at very different stages of their demographic transitions. Key trends in population size, fertility and mortality during these transitions are summarized below. The focus is on the century from 1950 to 2050, covering the period of most rapid global demographic change. The main source of data is the United Nation's 2006 world population assessment, which provides estimates for 1950-2005 and projections from 2005 to 2050 ( United Nations 2007).

2. Future population trends

The projected rise in world population to 9.2 billion in 2050 represents an increase of 2.7 billion over the 2005 population of 6.5 billion. Nearly all of this future growth will occur in the 'South'-i.e. Africa, Asia (excluding Japan, Australia and New Zealand), and Latin America-where population size is projected to increase from 5.3 to 7.9 billion between 2005 and 2050 ( table 1 ). In contrast, in the 'North' (Europe, Northern America, Japan and Australia/New Zealand), population size is forecast to remain virtually stable, growing slightly from 1.22 to 1.25 billion between 2005 and 2050. The difference in trends between these two world regions reflects the later stage of the transition in the North compared with the South.

Table 1.

population (billions)

% increase

1950

2005

2050

1950-2005

2005-2050

The global demographic transition began in the nineteenth century in the now economically developed parts of the world (the North) with declines in death rates. Large reductions in birth rates followed in the early part of the twentieth century. These transitions are now more or less complete. But, as shown in table 1 , trends for the two principal regions in the North are expected to diverge between 2005 and 2050: an increase from 0.33 to 0.45 billion in Northern America, and a decline from 0.73 to 0.66 billion in Europe. In fact, several countries in Europe (e.g. Russia) and East Asia (e.g. Japan) face significant population declines as birth rates have fallen below death rates.

The demographic transitions in Africa, Asia and Latin America started later and are still underway. In 2005, Asia had a population of 3.94 billion, more than half of the world total, and its population is expected to grow by 34 per cent to 5.27 billion by 2050. Africa, with 0.92 billion inhabitants in 2005, is likely to experience by far the most rapid relative expansion, more than doubling to 2.0 billion by 2050. Latin America, with 0.56 billion in 2005, is the smallest of the regions of the South; its projected growth trend is similar to that of Asia.

It may seem surprising that population growth continues at a rapid pace in sub-Saharan Africa, where the AIDS epidemic is most severe. This epidemic has indeed caused many deaths, but population growth continues because the epidemic is no longer expanding and the birth rate is expected to remain higher than the elevated death rate in the future ( UNAIDS 2007; Bongaarts et al. 2008). The epidemic's demographic impact can be assessed by comparing the standard UN population projection (which includes the epidemic's effect) with a separate hypothetical projection in which AIDS mortality is excluded ( United Nations 2007). In sub-Saharan Africa, the former projects a 2050 population of 1.76 billion and the latter a population of 1.95 billion. The difference of 0.2 billion in 2050 between these projections with and without the epidemic is due to deaths from AIDS as well as the absence of the descendents from people who died from AIDS. According to these projections, the population of sub-Saharan Africa will grow by one billion between 2005 and 2050 despite the substantial impact of the AIDS epidemic. In fact, no country is expected to see a decline in its population size between 2005 and 2050 due to high AIDS mortality. Most populations in sub-Saharan Africa will more than double in size, several will triple and Niger is expected to quadruple by 2050 ( United Nations 2007).

Transitions in the developing world have generally produced more rapid population growth rates in mid-transition than historically observed in the North. In some developing countries (e.g. Kenya and Uganda), peak growth rates approached four per cent per year in recent decades (implying a doubling of population size in two decades), levels that were very rarely observed in developed countries except with massive immigration. Two factors account for this very rapid expansion of population in these still largely traditional societies: the spread of medical technology (e.g. immunization, antibiotics) after World War II, which led to extremely rapid declines in death rates, and a lag in declines in birth rates.

Population sizes for the 10 largest countries in 2005 and in 2050 are presented in table 2 . In 2005, China (1.31 billion) and India (1.13 billion) were by far the largest countries, together accounting for nearly half the South's total. The top 10 include six Asian countries and only one country each in Latin America and Africa. By 2050, the ranking is expected to have shifted substantially, with India's population exceeding China's, and with Ethiopia and DR Congo rising to the top 10, replacing Japan and the Russian Federation.

Table 2.

rank

1995

2050

country

population size (millions)

country

projected population (millions)

To simplify the presentation of results, all projections discussed in this study are taken from the medium variant of the UN projections ( United Nations 2007). The UN has a good record of making relatively accurate projections ( National Research Council 2000), but the future is of course uncertain and actual population trends over the next half century will likely diverge to some extent from current projections. The UN makes an effort to capture this uncertainty by publishing separate high and low projections. For the world, the high and low variants reach 7.8 and 10.8 billion, respectively, in 2050, indicating a rather wide range of possible outcomes (see dashed lines in figure 1 ).

3. Drivers of population growth: fertility and mortality

The world's population increases every year because the global birth rate exceeds the death rate. For example, in 2000-2005 population size increased at a rate of 1.17 per cent per year, which equals the difference between a birth rate of 2.03 per cent and a death rate of 0.86 per cent. At the country level, population growth is also affected by migration, but for the regional aggregates of population used in this analysis, migration is usually a minor factor, and it will therefore not be discussed in detail.

The annual birth and death rates of populations are in turn primarily determined by levels of fertility and mortality experienced by individuals. The most widely used fertility indicator is the total fertility rate (TFR), which equals the number of births a woman would have by the end of her reproductive years if she experienced the age-specific fertility rates prevailing in a given year. Mortality is often measured by the life expectancy (LE) at birth, which equals the average number of years a newborn would live if subjected to age-specific mortality rates observed in a given year.

(a) Fertility

The UN's past estimates and future projections of fertility levels by region for the period 1950-2050 are presented in figure 2 . In the 1950s, the TFR in the South was high and virtually stable at around six births per woman on average. This high level of fertility reflects a near absence of birth control, a condition that has prevailed for centuries before the middle of the twentieth century. In the late 1960s, a rapid decline in fertility started nearly simultaneously in Asia and Latin America. In contrast, Africa has experienced only limited reproductive change. As a result of these divergent past trends, fertility levels in 2000-2005 differed widely among regions from as high as 5 births per woman (bpw) in Africa, to 2.5 bpw in Asia and Latin America. Average fertility in the North was already low in the early 1950s and has since declined to 2.0 bpw in Northern America and to 1.4 bpw in Europe.

The decline in the average fertility in the South from 6 to 3 bpw over the past half century has been very rapid by historical standards. This reproductive revolution is mainly due to two factors. First, desired family size of parents has declined as the cost of children rose and child survival increased. Second, government intervention played a key role. In China this took the form of a coercive and unpopular one-child policy, but most other countries implemented voluntary family planning programmes. The aim of these programmes is to provide information about and access to contraceptives at subsidized prices so that women who want to limit their childbearing can more readily do so.

UN projections for the South assume that the TFR will eventually reach and then fall slightly below the so-called 'replacement' level in all regions. Replacement fertility is just above 2 bpw and it represents the level at which each generation just replaces the previous one, thus leading to zero population growth (in the absence of mortality change and migration). Below-replacement fertility produces, in the long run, population decline. As is evident from figure 2 , the TFRs in Asia and Latin America are expected to reach the replacement level around 2020. Africa is assumed to be on a much slower trajectory towards replacement fertility because of its lower level of socio-economic development. High fertility therefore remains a key cause of future population growth in this region. In contrast, the already low fertility of the North is expected to remain below replacement and is no longer driving population growth.

(b) Mortality and life expectancy

Mortality levels have also changed rapidly over the past several decades ( figure 3 ). The South experienced exceptional improvements in LE from an average of 41 years in 1950-1955 to 64 years in 2000-2005. By the early 2000, Latin America reached mortality levels similar to those prevailing in the North in the 1970s, and Asia was just a few years behind. Africa experienced the highest mortality and improvements in LE stalled in the 1990s due to the AIDS epidemic. As a result, Africa's LE, at 52 years in 2000-2005, was still substantially below that of Asia (68) and Latin America (72). As expected, Europe and Northern America already achieved relatively low levels of mortality by 1950, but they have nevertheless seen significant further improvements since then. Europe's LE (74) is now lower than North America's (78) because of a rise in mortality in Eastern Europe after the break-up of the Soviet Union.

Projections of future LEs by the UN assume continued improvements over time in all regions. The North is expected to reach 82 years in 2050 despite the increasing difficulty in achieving increments as countries reach ever higher levels of LE. Asia and Latin America are expected to continue to close the gap with the North, and Africa will continue to lag, in part because the continent remains affected by the AIDS epidemic.

It should be noted that the assumptions made by the UN about future trends in fertility and mortality are not based on a firm theoretical basis. Instead, the UN relies on empirical regularities in past trends in countries that have completed their transitions, mostly in the North, where fertility declined to approximately the replacement level, and increases in LE became smaller over time. This is a plausible approach that unfortunately leaves room for potential inaccuracies in projection results.

4. Changing population age composition

Over the course of the demographic transition, declines in fertility and mortality cause important changes in a population's age composition. In general, countries in the early stages of the transition have a younger age structure than countries in the later stages.

Figure 4 presents the distribution of the 2005 population in four broad age groups: 0-14, 15-24, 25-64 and 65+ by region. Most of the regions in the South-Africa, Latin America, South Asia and West Asia-have very young age structures with about half of the population under age 25 (62% in Africa). The exception is East Asia (mostly China) where this proportion is 37 per cent. In the North, the population under 25 is still smaller: 35 per cent in North America and just 30 per cent in Europe. The reverse pattern is observed for the proportion 65+, which is much higher in the North than in the South, ranging from as high as 15 per cent in Europe to as low as just 3 per cent in Africa.

(a) The age-dependency ratio

A changing age distribution has significant social and economic consequences, e.g. for the allocation of education, healthcare and social security resources to the young and old. Assessments of this impact often rely on the so-called age-dependency ratio (DR) that summarizes key changes in the age structure. The DR at a given point in time equals the ratio of population aged below 15 and over 65 to the population of age 15-64. This ratio aims to measure how many 'dependents' there are for each person in the 'productive' age group. Obviously, not every person below 15 and over 65 is a dependent and not every person between ages 15 and 65 is productive. Despite its crudeness, this indicator is widely used to document broad trends in the age composition.

Over the course of a demographic transition, the DR shows a characteristic pattern of change. Figure 5 presents this pattern as observed in the South from 1950 to 2005 and projected from 2005 to 2050. Early in the transition, the DR typically first rises slightly as improvements in survival chances of children raise the number of young people. Next, the DR falls sharply as declines in fertility reduce the proportion of the population under age 15. This decline has important economic consequences because it creates a so-called 'demographic dividend', which boosts economic growth by increasing the size of the labour force relative to dependents and by stimulating savings ( Birdsall et al. 2001). Finally, at the end of the transition, the DR increases again as the proportion of the population over age 65 rises. Figure 5 also plots the DR of the North from 1950-2050. From 1950 to 2010 it showed a slight decline, but after 2010 it rises steeply as very low fertility and increasing longevity increases the proportion 65+. This ageing of the North poses serious challenges to support systems for the elderly (OECD 1998, 2001).

(b) Population momentum

At the end of the demographic transition natural population growth reaches zero once three conditions are met:

1. Fertility levels-off at the replacement level of about 2.1 bpw (more precisely, the net reproduction rate should be 1). If fertility remains above replacement, population growth continues.

2. Mortality stops declining. In practice, this is not likely to happen because improvements in medical technology and healthcare as well as changes in lifestyles, etc. will probably ensure continued increases in LE.

3. The age structure has adjusted to the post-transitional levels of fertility and mortality.

The adjustment of the age structure at the end of the transition takes many decades to complete. A key implication of this slow adjustment process is that population growth continues for many years after replacement fertility is reached if, as is often the case, the population is still relatively young when fertility reaches the replacement level. The tendency of population size to increase after a two-child family size has been reached is referred to as population momentum; it is the consequence of a young population age structure ('young' is defined relative to the age structure in the current life table) ( Bongaarts & Bulatao 1999).

The population momentum inherent in the age structure of a particular population at a given point in time can be estimated with a hypothetical population projection in which future fertility is set instantly to the replacement level, mortality is held constant and migration is set to zero. Since such a variant is not directly available from UN projections, it will not be presented here. However, the UN does provide 'instant replacement' projections in which mortality and migration trends are the same as in the standard projection. This projection gives an approximation of the combined effect on future growth of population momentum and declining mortality in the South because the role of migration is small. The difference between this hypothetical projection and the standard medium UN projection is a measure of the impact of high fertility on future population growth.

Results of these two projections are presented in figure 6 , which compares the per cent growth between 2005 and 2050 for regions in the South. The black bars give the growth in the standard (medium variant) projection and the grey bars give the growth in the 'instant replacement' projection. Three results are noteworthy. First, the two projections differ most in Africa (+117% versus +50%) which is as expected because fertility is still very high in this region. Second, in all regions of the South outside China, populations would be expected to rise by 50 per cent (62% in West Asia) if fertility were set to replacement in 2005. This implies that momentum and declining mortality are responsible for nearly half of the projected future population growth in Africa and for the large majority of growth in Latin America, and South and West Asia. Third, in East Asia and in Latin America the replacement projection exceeds the medium UN projection. This finding is explained by the fact that fertility in these regions is assumed to average below the replacement level over the next half century.

5. Conclusion

The world and most countries are going through a period of unprecedentedly rapid demographic change. The most obvious example of this change is the huge expansion of human numbers: four billion have been added since 1950. Other demographic processes are also experiencing extraordinary change: women are having fewer births and LEs have risen to new highs. Past trends in fertility and/or mortality have led to very young populations in high fertility countries in the South and to increasingly older populations in the North. Still other important demographic changes which were not reviewed here include rapid urbanization, international migration, and changes in family and household structure.

Global population growth will continue for decades, reaching around 9.2 billion in 2050 and peaking still higher later in the century. The demographic drivers of this growth are high fertility in parts of the South, as well as declining mortality and momentum. This large expansion in human numbers and of the accompanying changes in the age structure will have multiple consequences for society, the economy and the environment as discussed in the subsequent chapters in this issue.

Articles from Philosophical Transactions of the Royal Society B: Biological Sciences are provided here courtesy of The Royal Society

# data[].attributes.attachment_link.title
Human population growth and the demographic transition

# data[].attributes.attachment_link.description
The world and most regions and countries are experiencing unprecedentedly rapid demographic change. The most obvious example of this change is the huge expansion of human numbers: four billion have been added since 1950. Projections for the next half ...

# data[].attributes.headline
Wolf Reintroduction Changes Ecosystem in Yellowstone

# data[].attributes.subject
Wolf Reintroduction Changes Ecosystem in Yellowstone

# data[].attributes.attachment_link.readable_text
On a quiet spring morning, a resounding "Slap!" reverberates through the air above a remote stream leading to Lake Yellowstone. Over much of the past century, it has been a rarely heard noise in the soundscape that is Yellowstone National Park, but today is growing more common-the sound of a beaver slapping its tail on the water as a warning to other beavers.

When the grey wolf was reintroduced into the Greater Yellowstone Ecosystem in 1995, there was only one beaver colony in the park, said Doug Smith, a wildlife biologist in charge of the Yellowstone Wolf Project.

Today, the park is home to nine beaver colonies, with the promise of more to come, as the reintroduction of wolves continues to astonish biologists with a ripple of direct and indirect consequences throughout the ecosystem.

A flourishing beaver population is just one of those consequences, said Smith.

A Yellowstone Beaver's Tale of Elk

What happened, said Smith, is that the presence of wolves triggered a still-unfolding cascade effect among animals and plants-one that will take decades of research to understand.

"It is like kicking a pebble down a mountain slope where conditions were just right that a falling pebble could trigger an avalanche of change," Smith mused.

So how did this avalanche of change work out for the beaver?

To answer that, you have to go back to the 1930s, when the wolf was killed off in Yellowstone. Even though Yellowstone elk were still preyed upon by black and grizzly bears, cougars and, to a lesser extent, coyotes, the absence of wolves took a huge amount of predatory pressure off the elk, said Smith. As a result, elk populations did very well-perhaps too well. Two things happened: the elk pushed the limits of Yellowstone's carrying capacity, and they didn't move around much in the winter-browsing heavily on young willow, aspen and cottonwood plants. That was tough for beaver, who need willows to survive in winter.

Healthier Willow Stands in Yellowstone

This created a counterintuitive situation. Back in 1968, said Smith, when the elk population was about a third what it is today, the willow stands along streams were in bad shape. Today, with three times as many elk, willow stands are robust. Why? Because the predatory pressure from wolves keeps elk on the move, so they don't have time to intensely browse the willow.

Indeed, a research project headed by the U.S. Geological Survey in Fort Collins found that the combination of intense elk browsing on willows and simulated beaver cuttings produced stunted willow stands. Conversely, simulated beaver cutting without elk browsing produced verdant, healthy stands of willow. In the three-year experiment, willow stem biomass was 10 times greater on unbrowsed plants than on browsed plants. Unbrowsed plants recovered 84 percent of their pre-cut biomass after only two growing seasons, whereas browsed plants recovered only 6 percent.

With elk on the move during the winter, willow stands recovered from intense browsing, and beaver rediscovered an abundant food source that hadn't been there earlier.

As the beavers spread and built new dams and ponds, the cascade effect continued, said Smith. Beaver dams have multiple effects on stream hydrology. They even out the seasonal pulses of runoff; store water for recharging the water table; and provide cold, shaded water for fish, while the now robust willow stands provide habitat for songbirds.

"What we're finding is that ecosystems are incredibly complex," he said. In addition to wolves changing the feeding habits of elk, the rebound of the beaver in Yellowstone may also have been affected by the 1988 Yellowstone fires, the ongoing drought, warmer and drier winters and other factors yet to be discovered, Smith said.

Yellowstone Wolf Trophic Cascade

Biologists are often faced with the grim task of documenting the cascade effects of what happens when a species is removed from an ecosystem, by local extirpation or even extinction. In Yellowstone, biologists have the rare, almost unique, opportunity to document what happens when an ecosystem becomes whole again, what happens when a key species is added back into the ecosystem equation.

"In the entire scientific literature, there are only five or six comparable circumstances," Smith said. "What we're seeing now is a feeding frenzy of scientific research."

Scott Creel, an ecology professor at Montana State University, is hip-deep in that feeding frenzy.

"My research has been in the Gallatin Canyon," said Creel, where elk inhabit four drainages. Wolves come and go, he said, enabling him to study what elk do in the presence and absence of wolves.

"Elk have proven to be pretty adaptable," Creel said. "When wolves are around, they're more vigilant and do less foraging."

Elk move into heavy timber when wolves are around, Creel added, but return to the grassy, open meadows when wolves go away. Creel and other researchers are still working out what that means in terms of the elk's diet and whether there are costs associated with this behavior.

Rather surprisingly, elk herd size breaks up into smaller units when wolves are around, said Creel, who had expected herd size to get bigger as a defense mechanism. "I think they're trying to avoid encounters with wolves," he said, by being more vigilant, moving into the timber and gathering in smaller herd units.

Yellowstone Wolves are Food Distributors

Researchers have also determined that wolves, in the recent absence of hard winters, are now the primary reason for elk mortality. Before wolf reintroduction, deep snows were the main determinant of whether an elk was going to die.

Researchers from the University of California at Berkeley determined that the combination of less snow and more wolves has benefited scavengers both big and small, from ravens to grizzly bears.

Instead of a boom and bust cycle of elk carrion availability-as existed before wolves and when winters were harder-there's now a more equitable distribution of carrion throughout winter and early spring, said Chris Wilmers in the on-line journal Public Library of Science Biology. He added that scavengers that once relied on winter-killed elk for food now depend on wolf-killed elk. That benefits ravens, eagles, magpies, coyotes and bears (grizzly and black), especially as the bears emerge hungry from hibernation.

"I call it food for the masses," said Ed Bangs, wolf recovery coordinator for the U.S. Fish and Wildlife Service. He said he was genuinely surprised by the vast web of life that is linked to wolf kills. "Beetles, wolverine, lynx and more," he said. "It turns out that the Indian legends of ravens following wolves are true-they do follow them because wolves mean food."

# data[].attributes.attachment_link.title
Wolf Reintroduction Changes Ecosystem in Yellowstone

# data[].attributes.attachment_link.description
Wolves are causing a tropic cascade of ecological change, including helping to increase beaver numbers and bring back aspen and vegetation.

# data[].attributes.attachment_link.readable_text
Image

The food source for the Karner blue butterfly caterpillar ( Lycaeides melissa samuelis) is a plant called wild lupine ( Lupine perennis). The wild lupine requires fire to reduce overhanging plants that otherwise would outcompete it for needed sunlight. Thus, indirectly, the caterpillar needs fire to complete its life cycle.

Photograph by Science Stock

Wednesday, January 15, 2020

The year 2019 marked 75 years of Smokey Bear, the advertising icon of the United States Forest Service who encourages visitors and campers to prevent wildfires. Wildfires are destructive forces that can result from natural causes (like lightning), human-caused accidents (like cigarettes and campfires), or deliberate acts of arson. Despite Smokey's education campaigns, wildfires burned about four million hectares (10 million acres) of land during 2017, and in 2018, a single California wildfire, the "Camp Fire" destroyed nearly 20,000 structures and killed more than 80 people, with insured losses topping $10 billion. However, while these frightening and negative consequences dominate news headlines, forest fires have a positive side. Controlled use of wildland fires for positive environmental effects is common around the world.

While a wildfire refers to an unintentional, uncontrolled fire, the term "wildland fire" is broader and includes fires purposefully set as part of prescribed burns. While all fires have the potential to become dangerous to property and life, prescribed, or controlled, burns are planned extensively and performed with tight safety parameters. Humans have been performing such burns for thousands of years and for multiple reasons, but, today, they are mainly used to promote ecological health and prevent larger, more damaging, uncontrolled fires.

It might seem counterintuitive that a fire, which burns plant life and endangers animals within an ecosystem, could promote ecological health. But fire is a natural phenomenon, and nature has evolved with its presence. Many ecosystems benefit from periodic fires, because they clear out dead organic material-and some plant and animal populations require the benefits fire brings to survive and reproduce.

For example, as dead or decaying plants begin to build up on the ground, they may prevent organisms within the soil from accessing nutrients or block animals on the land from accessing the soil. This coating of dead organic matter can also choke outgrowth of smaller or new plants. When humans perform a prescribed burn, the goal is to remove that layer of decay in a controlled manner, allowing the other, healthy parts of the ecosystem to thrive. Moreover, nutrients released from the burned material, which includes dead plants and animals, return more quickly into the soil than if they had slowly decayed over time. In this way, fire increases soil fertility-a benefit that has been exploited by farmers for centuries.

Several plants actually require fire to move along their life cycles. For example, seeds from many pine tree species are enclosed in pine cones that are covered in pitch, which must be melted by fire for the seeds to be released. Other trees, plants, and flowers, like certain types of lilies, also require fire for seed germination.

Even some animals depend on fire. The sole food source for the endangered Karner blue butterfly caterpillar ( Lycaeides melissa samuelis) is a plant called wild lupine ( Lupine perennis). Wild lupine requires fire to maintain an ecosystem balance in which it can thrive. Without fire, the lupines do not flourish, and the caterpillars cannot consume enough food to undergo metamorphosis and become butterflies. In this way, healthier, post-burn plant populations generally have broad food web effects that trickle up to the foragers and other animals in the ecosystem. Similarly, animals that use pine trees for their homes benefit from the germinating powers of fire.

Perhaps surprisingly, the animal casualties from wildfires are low-animals survive by burrowing into the ground or fleeing to safer areas. Conversely, fires can help rid an ecosystem of invasive species that have not adapted to regular wildland fires. While animals and plants within fire-prone ecosystems have adapted to thrive within a cycle of wildfires, invasive plants and animals are less likely to recover and could thus be controlled or even eradicated from the ecosystem they invaded.

Moreover, prescribed burns are well established as a way to prevent more devastating naturally occurring fires. The buildup of decaying organic matter on the ground is fuel for wildfires. Without periodic fire to clear this out, a naturally occurring fire may grow and move quickly, doing much more damage that a prescribed burn-and without its safety parameters.

In the end, it is true that the burden of preventing uncontrolled wildfires lies with humanity. Smokey Bear's message is right-nearly 85 percent of wildfires originate from human activity, and we have to take action to prevent these damaging fires. But suppression is not enough. Nature needs fire, and ecologically benefits from periodic burning. In fact, suppression alone might make matters worse, depriving nature of its equivalent of spring cleaning and leading to hotter, larger blazes when built-up forest decay finally catches flame. Understanding and appreciating the benefits of fire is the only way to truly keep our homes, population, and ecosystem safe from its dangers.

Credits

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society
Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society
Margot Willis, National Geographic Society

Producer

Clint Parks

Last Updated

Jan. 15, 2020

User Permissions

For information on user permissions, please read our Terms of Service. If you have questions about licensing content on this page, please contact ngimagecollection@natgeo.com for more information and to obtain a license. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. She or he will best know the preferred format. When you reach out to him or her, you will need the page title, URL, and the date you accessed the resource.

Media

If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

Text

Text on this page is printable and can be used according to our Terms of Service.

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.

Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society
Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society
Margot Willis, National Geographic Society

Producer

Clint Parks

# data[].attributes.attachment_link.description
Wildfires are destructive forces, but they can occur naturally. Because of this, certain plants and animals have evolved to depend on periodic wildfires for ecological balance. Prescribed burns can mimic the benefits of wildfires while also lowering the risks associated with larger, uncontrolled fires.

# data[].attributes.headline
Which Animals will Survive Climate Change?

# data[].attributes.subject
Which Animals will Survive Climate Change?

# data[].attributes.attachment_link.readable_text
Climate change is exacerbating problems like habitat loss and temperatures swings that have already pushed many animal species to the brink. But can scientists predict which animals will be able to adapt and survive? Using genome sequencing, researchers from McGill University show that some fish, like the threespine stickleback, can adapt very rapidly to extreme seasonal changes. Their findings could help scientists forecast the evolutionary future of these populations.

A popular subject of study among evolutionary ecologists, stickleback are known for their different shapes, sizes, and behaviours -- they can even live in both seawater and freshwater, and under a wide range of temperatures. But what makes this species so resilient?

Identifying the genetic basis of adaptations, for example, to freshwater or in response to climate change, can be challenging. "The modern version of Darwin's idea of evolution by natural selection posits that organisms with genes that favour survival and reproduction will tend to leave more offspring than their peers, causing the genes to increase in frequency over generations. As a result, populations become adapted or better-suited to their environments over time," says lead author Alan Garcia-Elfring, a Doctoral Candidate under the supervision of Rowan Barrett, the Canada Research Chair of Biodiversity Science at McGill University.

"However, this process has typically been studied retrospectively, in populations that adapted to their current environments long in the past. This can make it difficult to understand the sequence of events -- for example, which traits were most important and when -- that led to their adaptation," he adds.
Natural selection in real-time
To study natural selection in action, the researchers tracked six populations of threespine stickleback fish before and after seasonal changes to their environment, using genome sequencing. Stickleback found in different estuaries along coastal California provide a rare opportunity to study natural selection in real-time. Seasonal changes driven by wet winters and dry summers result in drastic shifts in habitat structure and balance of salt versus freshwater, and only those fish able to tolerate these rapid changes survive into the next season.

Estuaries are periodically isolated from the ocean due to sandbar formation during dry summer months. "These changes probably resemble the habitat shifts experienced by stickleback populations when they colonized many newly created freshwater lakes from the ocean after the glaciers receded 10,000 years ago" says Professor Barrett. "We hope to gain insight into the genetic changes that may have resulted from natural selection long in the past."

Remarkably, the researchers discovered evidence of genetic changes driven by the seasonal shifts in habitat that mirrored the differences found between long-established freshwater and saltwater populations. "These genetic changes occurred in independent populations over a single season, highlighting just how quickly the effects of natural selection can be detected," says Alan Garcia-Elfring.

"The findings are important because they suggest that we may be able to use the genetic differences that evolved in the past as a way to predict how populations may adapt to environmental stressors like climate change in the future" he says.

The research underscores the importance of studying species in dynamic environments, like bar-built estuaries, to gain a better understanding of how natural selection operates. In further research, they plan to investigate how repeatable the observed genetic shifts are, by testing whether they show up year after year. Doing so would demonstrate their ability to reliably forecast the evolutionary future of these populations.

# data[].attributes.attachment_link.keywords[]
evolutionary biology; nature; wild animals; ecology research; environmental awareness; climate; global warming; ecology

# data[].attributes.attachment_link.title
Which animals will survive climate change? Genetic changes in threespine stickleback fish driven by seasonal shifts could help scientist predict how certain species will adapt to new environments

# data[].attributes.attachment_link.description
Climate change is exacerbating problems like habitat loss and temperatures swings that have already pushed many animal species to the brink. But can scientists predict which animals will be able to adapt and survive? Using genome sequencing, researchers show that some fish, like the threespine stickleback, can adapt very rapidly to extreme seasonal changes.

# data[].attributes.attachment_link.readable_text
Mangrove ecosystems should be better protected, the UN's food agency has warned as it published new figures showing that 20% of the world's mangrove area has been destroyed since 1980

A study by the Rome-based Food and Agriculture Organisation (FAO) said that the environmental and economic damages caused by the "alarming" loss of mangroves in many countries should be urgently addressed.

Countries must engage in more effective conservation and sustainable management of the world's mangroves and other wetland ecosystems, it warned, ahead of World Wetlands day tomorrow.

The world has lost around 3.6m hectares (20%) of mangroves since 1980, the report showed.

The total mangrove area has declined from 18.8m ha (46.4m acres) in 1980 to 15.2m ha (37.5m acres) in 2005. However the report did show that there has been a slowdown in the rate of mangrove loss: from some 187,000 ha destroyed annually in the 1980s to 102,000 ha a year between 2000 and 2005. This reflected an increased awareness of the value of mangrove ecosystems, the report said.

Mangroves are salt-tolerant evergreen forests that are found along coastlines, lagoons, rivers or deltas in 124 tropical and subtropical countries and areas around the world, providing protection against erosion, cyclones and wind.

Around 50% of the world's total mangrove area is found in Indonesia, Australia, Brazil, Nigeria and Mexico.
Their important ecosystems provide wood, food, fodder, medicine and honey for humans, and habitats for many animals like crocodiles and snakes, tigers, deer, otters, dolphins and birds. A wide range of fish and shellfish also depend on mangroves as the swamps help to filter sediment and pollution from water upstream and stop it disturbing the delicate balance of ecosystems like coral reefs.

The main causes of the destruction of mangrove swampland include population pressure, conversion for shrimp and fish farming, agriculture, infrastructure and tourism, as well as pollution and natural disasters, the FAO said.

"Mangroves are important forested wetlands and most countries have now banned the conversion of mangroves for aquaculture and they assess the impact on the environment before using mangrove areas for other purposes," said Wulf Killmann, the director of the FAO's forest products and industry division.
"This has lead to better protection and management of mangroves in some countries. But overall, the loss of these coastal forests remains alarming. The rate of mangrove loss is significantly higher than the loss of any other types of forests.

Shrinking mangrove forests "can lead to severe losses of biodiversity and livelihoods, in addition to salt intrusion in coastal areas and siltation of coral reefs, ports and shipping lanes," Killmann said.

Asia suffered the largest net loss of mangroves since 1980, with more than 1.9m ha destroyed, mainly due to changes in land use.
North and central America and Africa also contributed significantly to the decrease in mangrove area, with losses of about 690,000 and 510,000 ha respectively over the last 25 years. At the country level, Indonesia, Mexico, Pakistan, Papua New Guinea and Panama recorded the largest losses of mangroves during the 1980s. A total of some 1m ha were lost in these five countries - a land area equivalent to Jamaica. In the 1990s, Pakistan and Panama succeeded in reducing their rate of mangrove loss, while Vietnam, Malaysia and Madagascar suffered increased clearing and moved into the top five countries with major area losses in the 1990s and 2000-05.

"On a positive note, a number of countries have had an increase in mangrove area over time, including Bangladesh," said senior forestry officer, Mette Wilkie.
"Part of the largest mangrove area in the world, the Sundarbans reserved forest in Bangladesh, is well protected and no major changes in the extent of the area have occurred during the last few decades, although some damage to the mangroves was reported after the recent cyclone in 2007. In Ecuador, the abandoning of ponds and structures for shrimp and salt production led to a rebuilding of various mangrove sites," she said.

The assessment of the world's mangroves from 1980-2005 was prepared in collaboration with mangrove specialists throughout the world and was co-funded by the International Tropical Timber Organisation (ITTO).

The FAO and ITTO are currently working with the International Society for Mangrove Ecosystems and other partner organisations to produce a World Atlas of Mangroves to be published later this year.
Topics

# data[].attributes.attachment_link.title
Report reveals 'alarming' rate of mangrove habitat loss

# data[].attributes.attachment_link.description
Mangrove ecosystems should be better protected, the UN's food agency has warned as it published new figures showing that 20% of the world's mangrove area has been destroyed since 1980 A study by the Rome-based Food and Agriculture Organisation (FAO) said that the environmental and economic damages caused by the "alarming" loss of mangroves in many countries should be urgently addressed.

# data[].attributes.attachment_link.readable_text
New research shows that concentrations of the toxic element mercury in rivers and fjords connected to the Greenland Ice Sheet are comparable to rivers in industrial China, an unexpected finding that is raising questions about the effects of glacial melting in an area that is a major exporter of seafood.

"There are surprisingly high levels of mercury in the glacier meltwaters we sampled in southwest Greenland," said Jon Hawkings, a postdoctoral researcher at Florida State University and and the German Research Centre for Geosciences. "And that's leading us to look now at a whole host of other questions such as how that mercury could potentially get into the food chain."

The study was published today in Nature Geoscience.

The international study began as a collaboration between Hawkings and glaciologist Jemma Wadham, a professor at the University of Bristol's Cabot Institute for the Environment.

Initially, researchers sampled waters from three different rivers and two fjords next to the ice sheet to gain a better understanding of meltwater water quality from the glacier and how nutrients in these meltwaters may sustain coastal ecosystems.

One of the elements they measured for was the potentially toxic element mercury, but they had no expectation that they would find such high concentrations in the water there.

Typical dissolved mercury content in rivers are about 1 -- 10 ng L-1 (the equivalent of a salt grain-sized amount of mercury in an Olympic swimming pool of water). In the glacier meltwater rivers sampled in Greenland, scientists found dissolved mercury levels in excess of 150 ng L-1, far higher than an average river. Particulate mercury carried by glacial flour (the sediment that makes glacial rivers look milky) was found in very high concentrations of more than 2000 ng L-1.

With any unusual finding, the results raise more questions than answers. Researchers are unclear if the mercury levels will dissipate farther away from the ice sheet and whether this "glacier" derived mercury is making its way into the aquatic food web, where it can often concentrate further.

"We didn't expect there would be anywhere near that amount of mercury in the glacial water there," said Associate Professor of Earth, Ocean and Atmospheric Science Rob Spencer. "Naturally, we have hypotheses as to what is leading to these high mercury concentrations, but these findings have raised a whole host of questions that we don't have the answers to yet."

Fishing is Greenland's primary industry with the country being a major exporter of cold-water shrimp, halibut and cod.

"We've learned from many years of fieldwork at these sites in Western Greenland that glaciers export nutrients to the ocean, but the discovery that they may also carry potential toxins unveils a concerning dimension to how glaciers influence water quality and downstream communities, which may alter in a warming world and highlights the need for further investigation," Wadham said.

The finding underscores the complicated reality of rapidly melting ice sheets across the globe. About 10 percent of the Earth's land surface is covered by glaciers, and these environments are undergoing rapid change as a result of rising temperatures. Scientists worldwide are working to understand how warming temperatures -- and thus more rapidly melting glaciers -- will affect geochemical processes critical to life on Earth.

"For decades, scientists perceived glaciers as frozen blocks of water that had limited relevance to the Earth's geochemical and biological processes," Spencer said. "But we've shown over the past several years that line of thinking isn't true. This study continues to highlight that these ice sheets are rich with elements of relevance to life."

Hawkings also said it was worth noting that this source of mercury is very likely coming from the Earth itself, as opposed to a fossil fuel combustion or other industrial source. That may matter in how scientists and policymakers think about the management of mercury pollution in the future.

"All the efforts to manage mercury thus far have come from the idea that the increasing concentrations we have been seeing across the Earth system come primarily from direct anthropogenic activity, like industry," Hawkings said. "But mercury coming from climatically sensitive environments like glaciers could be a source that is much more difficult to manage."

Journal Reference:

Jon R. Hawkings, Benjamin S. Linhoff, Jemma L. Wadham, Marek Stibal, Carl H. Lamborg, Gregory T. Carling, Guillaume Lamarche-Gagnon, Tyler J. Kohler, Rachael Ward, Katharine R. Hendry, Lukáš Falteisek, Anne M. Kellerman, Karen A. Cameron, Jade E. Hatton, Sarah Tingey, Amy D. Holt, Petra Vinšová, Stefan Hofer, Marie Bulínová, Tomáš Větrovský, Lorenz Meire, Robert G. M. Spencer. Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet. Nature Geoscience, 2021; DOI: 10.1038/s41561-021-00753-w

# data[].attributes.attachment_link.keywords[]
nature; extreme survival; drought; fisheries; global warming; water; snow and avalanches; environmental science

# data[].attributes.attachment_link.title
Greenland glacial meltwaters rich in mercury

# data[].attributes.attachment_link.description
New research shows that concentrations of the toxic element mercury in rivers and fjords connected to the Greenland Ice Sheet are comparable to rivers in industrial China, an unexpected finding that is raising questions about the effects of glacial melting in an area that is a major exporter of seafood.

# data[].attributes.headline
Biodiversity protects Fish from Climate Change

# data[].attributes.subject
Biodiversity protects Fish from Climate Change

# data[].attributes.attachment_link.readable_text
Fish provide protein to billions of people and are an especially critical food source in the developing world. Today marine biologists confirmed a key factor that could help them thrive through the coming decades: biodiversity. Communities with more fish species are more productive and more resilient to rising temperatures and temperature swings, according to a new study from the Smithsonian's Tennenbaum Marine Observatories Network and other international institutions.

The accelerating loss and rearrangement of species all over the globe have troubled scientists and the public for decades. But the question of whether biodiversity offers practical value-for humans and ecosystems-remained controversial. The new study, published May 16 in the Proceedings of the National Academy of Sciences, offers the most thorough proof yet that preserving marine biodiversity can benefit people as much as it benefits the oceans.

"Biodiversity is more than a pretty face," said lead author Emmett Duffy, director of the Tennenbaum Marine Observatories Network and senior scientist at the Smithsonian Environmental Research Center. "Preserving biodiversity is not just an aesthetic or spiritual issue-it's critical to the healthy functioning of ecosystems and the important services they provide to humans, like seafood."

The discovery came out of the Reef Life Survey, a comprehensive program that has conducted surveys of more than 3,000 fish species in 44 countries around the world. Many of the surveyors were volunteer citizen scientists, about a third of whom had no scientific background. Volunteer divers from 11 countries received training from the program's lead scientists at the University of Tasmania to collect data using standardized methods.

"This study is based on more than 4,000 underwater surveys," said co-author Rick Stuart-Smith of the University of Tasmania. "It was only possible with the enthusiastic contributions of highly trained volunteer divers in the Reef Life Survey program, which allowed us to achieve this comprehensive coverage of the world's reefs, from tropical to polar waters."

Armed with the most comprehensive global dataset on marine biodiversity involving standardized counts, the researchers tracked how 11 different environmental factors influenced total fish biomass on coral and rocky reefs around the world. Surprisingly, one of the strongest influences was biodiversity: The number of species (species richness) and the variety in how they use their environment (functional diversity)enhanced fish biomass. The boost in fish resources provided by biodiversity was second only to that of warm temperatures.

Temperature had a more complex relationship with fish biomass: Warmer ocean temperatures tended to boost fish biomass on average, while wider temperature fluctuations hindered it. But biodiversity made fish communities more resilient against changing climate. In communities with only a few species, fish biomass tended to increase with rising temperatures until seas warmed above 20 degrees Celsius (68 degrees Fahrenheit)-at which point biomass started to fall. But communities with many species remained stable at these higher temperatures.

The researchers found a similar buffering effect of diversity against temperature swings. While both high- and low-diversity communities were less productive under fluctuating temperatures, high-diversity communities suffered only half as much as low-diversity ones. The researchers suspect communities with more species are better equipped to handle temperature changes because they have more of their bases covered. When temperatures fluctuate, a community with numerous species has better odds that at least a few species can thrive in the new normal.

"This work is a critical step forward in linking insights from experiments in buckets and garden plots to the larger world," said co-author Jonathan Lefcheck of the Virginia Institute of Marine Science, referring to earlier biodiversity experiments done with plants and small animals in gardens or greenhouses. "It shows that experimental ecologists have in fact been on the right track for 20 years, and that biodiversity is paramount to how natural systems work."

"Preserving local biodiversity is not only an ethical directive with aesthetical and genetic insurance value," said co-author Sergio Navarrete of the Pontifical Catholic University of Chile. "It is an imperative for human life because of the critical role it plays in providing an essential ecosystem function."

For images, an advance copy of the paper or to speak to the authors, contact Kristen Minogue at 443-482-2325 or minoguek@si.edu.

# # #

SI-250-2016

# data[].attributes.attachment_link.title
Biodiversity Protects Fish From Climate Change

# data[].attributes.attachment_link.description
Fish provide protein to billions of people and are an especially critical food source in the developing world. Today marine biologists confirmed a key factor that could help them thrive through the coming decades: biodiversity.

# data[].attributes.attachment_link.readable_text
1. Introduction

Pollination by insects is a critical ecosystem service that is necessary for production of most crops, including those providing essential micronutrients, and is thus essential for food security [ 1]. In the USA, the production of pollinator-dependent crops is valued at over $50 billion per year [ 2, 3]. Recent evidence that both European honeybees ( Apis mellifera) and some native wild bee species are declining [ 4- 6] raises concern about negative impacts on crop yield (amount produced per area). However, a decline in pollinators will only affect crop yield if yield is limited by a lack of pollination. Research on pollinator limitation, or the degree to which a lack of pollinators is restricting full seed or fruit production, has focused mainly on wild plant species [ 7- 8], with little information available about the frequency or circumstances in which pollination limits crop production [ 9- 13].

Theoretically, for any pollinator-dependent crop, we expect a relationship between pollination and crop yield, such that yield increases with pollination until the crop is fully pollinated, at which point additional pollinators contribute no further service ( figure 1) [ 7]. When a crop is pollination limited, we expect a positive relationship between pollination and yield, such that crop fields receiving more pollination also produce higher yields. Conversely, if pollination is not limiting, we expect no relationship between pollination and yield. Across farms that differ in pollination, we would expect farms with lower visitation to show lower yield, but there might not be a relationship between visitation and yield among farms with high visitation rates. Pollination may not be limiting for two fundamentally different reasons. First, yield is not pollination limited if the crop plant's pollination threshold is met (i.e. the number of pollen grains deposited is sufficient for maximum fruit production under ideal growth conditions). Second, even if the plant's pollination threshold is not met, pollination will not be a limiting factor if some other factor is more limiting to yield (e.g. [ 14- 16]). Common limiting factors for crop production include a lack of water or nutrients (fertilizer) and injury from plant pests and diseases [ 7, 17]. When other factors are limiting, crop yield will not increase with increasing pollination, even if pollination is insufficient. Thus, we expect that commercial farms, which typically have high inputs for irrigation, fertilizer and pest management, would be particularly sensitive to deficits in pollination. However, whether intensively managed crops in major production areas are in fact limited by pollination has rarely been tested (but see [ 12]).

In many agricultural situations, pollination is provided by a combination of managed honeybees (or sometimes other managed bees) and wild insects (primarily wild bees). While honeybees have long been considered the most economically valuable pollinators, recent global syntheses have revealed that wild pollinators are often as abundant as honeybees on crop flowers [ 18- 20], and that the diversity of wild bee visitors is higher when crops are grown in their biogeographic region of origin [ 21]. Furthermore, flower visits by wild bees are more strongly correlated with crop yields than are visits by honeybees [ 18, 22, 23]. The reason for this association is not known, but could include some wild bee species depositing more pollen per visit than honeybees [ 22, 24], wild bees moving more often between compatible plants, or wild bees increasing the pollination provided by honeybees through interspecific interactions [ 25, 26]. Wild pollinators might be contributing significantly to crop pollination at the national scale in the USA, but this has not been evaluated in a comprehensive way.

An ideal nationwide assessment of crop pollination should study multiple economically important bee-pollinated crops, each in its main region(s) of production. An assessment should also capture the effects of typical management practices, including honeybee stocking rates. We expect high stocking density in major production regions because in intensively managed landscapes many wild bee species have reduced abundance or fail to persist [ 24, 27- 30]. Thus, in the settings where most crop production occurs, the contribution of wild bees might be considerably less than that of honeybees.

The economic value of honeybees and wild bees can be estimated based on their relative contributions to crop pollination. The production value method, which has most often been used to economically value pollination [ 2, 31], begins with the market value (price × quantity) of the crop and attributes to pollinators the fraction of this value that would be lost in the absence of pollination. This fraction can be less than the entire market value for crops that still produce some yield when pollinators are absent [ 32]. This total economic value can then be partitioned into components attributable to honeybees and to wild bees. Estimates from the production value method are best interpreted as short term, on a time scale in which alternative strategies such as switching to less pollinator-dependent varieties are not available [ 33].

In this paper, we report the results of a national-scale empirical study of seven pollinator-dependent crops and 131 commercially managed fields across the USA and part of Canada. We answer the following questions. (i) How prevalent is pollinator limitation? (ii) What are the relative contributions of wild bees and the honeybees to crop production or yields? (iii) How do these contributions translate into economic value?

2. Methods

(a) Study design

We collected data on insect pollination and crop production for highbush blueberry ( Vaccinium corymbosum), apple ( Malus pumila), sweet cherry ( Prunus avium), tart cherry ( Prunus cerasus), almond ( Prunus dulcis), watermelon ( Citrullus lanatus) and pumpkin ( Cucurbita pepo) at farms across the USA and part of Canada (electronic supplementary material, figure S1). All of these crops depend very strongly or absolutely on insect pollination [ 32]. For each crop, we selected study farms within economically important areas for the national production of that crop, so these farms were representative of the majority of production in terms of growing conditions, pollinator communities and farm management practices. In addition, the individual farm fields selected were reasonably large and well-maintained as per standard agricultural practice, and were growing a regionally common cultivar. All fields were stocked with honeybee hives at rates typical for the region. For pumpkin and apple in Pennsylvania, not all farmers routinely stock honeybees because native bees are thought to provide sufficient pollination (e.g. [ 34]). However, even when honeybees were not stocked at our study sites, they were still found on crop flowers.

(b) Data collection: pollinator visitation rates and crop production metrics

Within each crop field, insect pollinators were observed during bloom along four 100 m transects, positioned approximately 0, 25, 50 and 100 m into the field from one edge. Along each transect, observers stopped every few metres and observed a small patch of flowers to which all visiting bees could reliably be counted. Each visiting bee was identified to an on-the-wing species group, such as ' Bombus', ' Xylocopa' or 'green bee' (electronic supplementary material, table S2). Bee species were grouped based on body size and hairiness, which are the two main predictors of pollen deposition per visit [ 35, 36]. Honeybees were always identified uniquely to species. In each year (two or three years depending on crop), bees were counted on up to three different days during peak crop bloom, and up to three times per day, during weather conditions when bees were active. Methods for observing bee visits were standardized to the extent possible, but also tailored to each crop based on, for example, the density and distribution of flowers. Crop-specific visitation assessment protocols are listed in electronic supplementary material, table S3.

Crop production data were collected for each crop field within the same four transects where bee observations were performed. In each transect, production was assessed for a standard number of trees (orchard crops), bushes (berry crops) or quadrats (field crops). For each crop, we measured a crop production variable that was potentially related to pollination and also relevant to economic value. We used fruit weight when available or otherwise fruit set or number of fruit. Thus for some crops (watermelon and pumpkin), our crop production measurements are explicitly per area and thus correspond directly to yield. For the other crops, our measurements are not explicitly per area and are thus better referred to more generally as 'production'. Regardless, our measures of production match commonly used proxies for yield in the insect pollination literature [ 18, 37]. Flower counts were performed during peak bloom, then paired later with post-bloom fruit counts from the same sample locations to determine fruit set. Fruit weights and fruit counts were measured just prior to harvest. Crop-specific protocol details are listed in electronic supplementary material, table S4.

(c) Analysis 1: frequency of pollinator limitation

To measure the frequency of pollinator limitation across all locations for a given crop, we created three potential statistical models relating the number of bee visits observed to crop production and used AIC to choose between them ( figure 1; electronic supplementary material, Methods). The three models were: (i) a linear positive relationship, implying that all locations were pollinator limited; (ii) no relationship (an intercept only model), implying that no locations were limited; or (iii) an asymptotic (piecewise) regression model in which production increases with visitation to a certain visit rate breakpoint, then remains flat, implying that the crop is pollinator limited in some locations and not others. If the third model was selected, we estimated the frequency of pollinator limitation as the proportion of locations falling below the breakpoint.

(d) Analysis 2: contribution of honeybees versus wild bees

For each crop, the fraction of total pollen grains deposited by honeybees and each species group of wild bee was estimated by multiplying flower visits by that bee group (data collection described above) with an estimate of pollen grains deposited per visit (pollinator efficiency) for that group, and then calculating the proportion of the total pollination provided by each bee group (details in electronic supplementary material, Methods). Values of pollinator efficiency were taken from the literature and are listed in electronic supplementary material, table S2, along with associated sample sizes.

(e) Analysis 3: economic valuation

The economic value delivered to each crop in each state by honeybees and wild bees was calculated using the equation

where V pollinator is the annual economic value attributable to a particular pollinator group (either wild bees or honeybee), V crop is the annual production value of the crop, D is the pollinator dependency value for the crop (the proportion by which yield is reduced in the absence of pollination [ 32]) and P pollinator is the proportion of total pollination of the crop provided by the pollinator group, as estimated above.

Our approach updates previous national-scale estimates of the value of wild and honeybee pollination in several ways. First, previous national valuations (e.g. [ 2, 38]) did not have access to empirical data for the percentage of pollinator visits provided by each pollinator group ( P pollinator), but rather assumed a P honeybee value of 0.9 for crops in which honeybees were routinely supplied, unless expert opinion suggested the use of a different value [ 39]. In our study, we actually measured honeybee and wild bee visitation to each crop. Second, most previous studies come from one area in the USA, which often is not within the main production area for the crop. Our field sites were in states that are among the top national producers of each crop (electronic supplementary material, table S5), which is essential when such estimates are used to extrapolate to national value. Third, we based our economic valuations on estimated pollen deposition by each type of pollinator (by weighting flower visitation rates by the number of pollen grains deposited per flower visit), not merely on flower visitation rates, as has been done by most previous national-scale valuations. Details of our valuation methods, including extrapolations to the national level, are discussed in the electronic supplementary material, Methods.

3. Results

(a) Frequency of pollinator limitation

For each crop-state combination in our study, we used AIC model selection to estimate the frequency of pollinator limitation ( figure 2; electronic supplementary material, tables S6 and S7). For tart cherry in Michigan, sweet cherry in Washington, and for blueberry in Michigan, Oregon and British Columbia, we found evidence of pollinator limitation for most sampled areas (64-94% of transects). For watermelon, pumpkin and almond, we found little to no evidence of pollinator limitation. For apple in both Michigan and Pennsylvania, the best model was a linear relationship between visitation and crop production across all transects with no evidence of an asymptote, suggesting pollinator limitation across all sampled areas. Apples are typically thinned to achieve fruit that meet fresh-market standards; thus, our apple fruit counts were taken post-thinning to be more directly related to harvestable yield. This is a conservative approach, because post-thinning measurements are less likely than those taken pre-thinning to detect the effect of pollinator limitation. Plots of best-fit lines for each of the three models and estimated breakpoints between limiting and asymptotic pollination are shown in electronic supplementary material, figure S2. For blueberry, we performed a second analysis of pollen limitation using additional field data from hand-pollination experiments (electronic supplementary material, supplementary analysis 3). Results from this analysis were qualitatively similar to the results from the main analysis, in that they showed pollen limitation in farms with lower visitation, but not in farms with higher visitation (i.e. the segmented relationship was selected) for northern blueberry and showed no evidence of pollen limitation in Florida blueberry.

(b) Contribution of honeybees versus wild bees

On average across the 13 crop-state combinations measured in our study, 74% of observed visits were performed by honeybees and the other 26% by wild bees. However, this proportion differed greatly by crop (electronic supplementary material, figure S3). Wild bee visits accounted for the largest proportion in pumpkin (74.6%) and the lowest in almond (0%). The proportion of wild bee visits was higher for cherry and apple (average of 43.5% in sweet cherry, 34.7% in tart cherry, and 32.9% in apple) than for blueberry (average of 8.9%). The proportion of visits from each type of bee was remarkably consistent across states within each crop, with the exception of watermelon, for which wild bees were four times as abundant in Florida as compared with California.

Incorporating the data on pollen deposition per visit into the calculations increased the relative contribution of wild bees for most crops ( figure 3). Although visitation rates of honeybees were higher than those of wild bees in apple and tart cherry, the amount of pollen deposited by wild bees was equal or even somewhat greater because wild bee groups deposited an estimated 1.5 to 2 times more pollen per visit in these crops (electronic supplementary material, table S2). Wild bees contributed slightly more in Florida watermelon, and continued to be dominant in pumpkin. Incorporating pollen deposition per visit into calculations for blueberry, almond and California watermelon made little difference due to the low abundance of wild bees. The exception was sweet cherry, in which wild bees provided 43% of visits, but only 28% of pollen deposition. This was because the most abundant wild pollinators in this system were bumblebees, which have been shown to be ineffective pollinators of cherry flowers [ 40].

(c) Economic valuation

For the crops in our study, a high value of wild bees was estimated when the relative importance of wild bees was greater than that of honeybees (e.g. in pumpkin in Pennsylvania), or when the value of the crop was high overall (e.g. in Washington cherry and Michigan apple). However, for almond, which had the largest total national value, the subset of value attributable to wild bees was negligible because they were very rare or absent in the observations of pollinators in those farms. At the national level, we estimated the value of wild pollinators to be highest in apple, with a value of $1.06 billion, with significant value also in sweet cherry ($145 million), watermelon ($146 million), pumpkin ($101 million), blueberry ($50 million) and tart cherry ($32 million) ( figure 4), totalling approximately $1.5 billion across these crops alone. By contrast, wild bees provided very limited value to almond (actually $0 based on our study farms). The economic value of honeybees to crop yield across these crops, when estimated in the same manner, totalled about $6.4 billion, with this value dominated by their $4.2 billion value to almond. An alternative analysis that accounts for the potential for farmers to reduce financial losses by limiting other input costs when pollination fails and the crop will not be harvested is presented as electronic supplementary material, analysis 1. Using this method, estimated values are considerably lower for both wild bees and honeybees because variable production costs are subtracted from the yield value attributable to bees.

4. Discussion

Global reliance on pollinator-dependent crops has increased over the past several decades [ 1, 41], while wild and managed pollinators have declined in many places (e.g. [ 5, 42, 43]), prompting concern that pollinator limitation could pose a risk to yield stability and food security [ 44, 45]. In a multi-region study focusing on major production regions for fruits, vegetables and nuts in North America, we found evidence of pollinator limitation in five of the seven pollinator-dependent crops we examined. This is consistent with a growing body of literature that suggests pollination may be limiting across a wide range of crops worldwide [ 11- 13, 18, 44, 46]. An earlier meta-analysis found little or no evidence of limitation in most global crop systems [ 47], but these conclusions were based on an indirect analysis of temporal trends in yield, rather than measuring the relationship between bee abundance and yield directly. Our new evidence of pollinator limitation is particularly valuable in comparison to previous analyses, because we specifically targeted larger commercial farms that represent the context for the majority of production.

We found the overall contribution of wild bees to be similar to (or higher than) that of honeybees in most of the crops we studied ( figure 3). This result is in contrast to our expectation that sampling in agriculturally intensive areas would reveal greatly reduced wild bee contributions to crop pollination. Our data suggest that instead, wild bees are able to persist in many of these managed landscapes and make a significant, although variable, contribution to crop pollination. Furthermore, in all six crops we studied, the wild bee species, on average, deposited more pollen per visit than did the honeybee, by a factor of 1.4 to 3.2. (electronic supplementary material, table S2 and figure S4). We found a predominance of pollination by honeybees in certain crops (blueberry, California watermelon and almond), and this may be due to landscape factors, farm management intensity and/or pesticide use patterns that limit the ability of wild bees to persist and contribute to crop yield in these crops, in addition to differences in honeybee stocking rates. For instance, in California almond, visitation rates by wild bees are much lower (or more often non-existent) in the large-scale orchards we surveyed than in smaller farms surrounded by natural habitat [ 48] where much of the previous research on wild bees and almond pollination has been conducted. This pattern has also been seen in watermelon [ 24] and blueberry [ 10].

Our study reconciles previous conflicting evidence for the relative importance of honeybees, a managed agricultural input that growers must pay for each year, and wild bees, which provide a free ecosystem service, in pollination of crops grown across the United States. Previous national-level studies of the USA have estimated honeybees to be much more important than wild bees [ 2, 38, 39], but did not actually measure wild bee abundance in crop fields. By contrast, more recent syntheses of global literature have concluded wild bees may be at least as important as honeybees, if not more so [ 18, 19, 28]. We found that wild bee abundance on crop flowers in major US and Canadian production regions is higher than previously thought, and that this, combined with the greater pollination efficiency of many native bees, makes their importance in agricultural pollination more in line with previous estimates from other parts of the world than with previous estimates from the USA.

It is important to note that even when the proportion of visits by wild bees was fairly similar between two crops, including crops that are in the same genus and flower at the same time of year, the actual species of wild bee pollinating each crop differed (e.g. [ 49]). For instance, the vast majority of wild bee visits in sweet cherry in Washington were performed by bumblebees, while most wild insect visits in tart cherry in the eastern USA were performed by distantly related bee species (in this case various species in the genus Andrena). Similar differences are also known for squash/pumpkin in the Northeast and mid-Atlantic, where bumblebees and squash bees comprise most of the wild bee visits [ 50, 51], versus California, where bumblebee visits are relatively rare [ 52]. This variability in bee fauna highlights the need to sample broadly across production regions [ 49, 53] to better understand the role of specific types of wild bees for crop yields.

The natural history of specific crops and pollinators may explain some of the variation in pollinator limitation that we found among crops. The most obvious difference appeared to be between the early spring-blooming tree and perennial bush crops (apple, cherry and blueberry) that generally had much higher levels of pollinator limitation than the later summer-blooming annual crops (watermelon and pumpkin). Early bloom phenology is expected to negatively affect the abundance of both honeybees and wild bees. In the early spring, cool or rainy weather often suppresses bee visitation [ 54- 56], and if too few bees are active when flowers are blooming, pollinator limitation can result. Honeybees, even if maintained at high densities, do not typically fly in inclement weather, making spring-blooming crops more dependent on wild pollinators than those flowering in summer. These include species that are adapted to spring weather, but often do not achieve high abundance both due to lack of suitable habitat or, in the case of Bombus spp., because bees present at that time are foraging queens who have yet to produce a worker-filled colony. Later in the season, temperatures are more suitable for bee flight in general, resulting in a greater chance of good foraging weather during bloom of summer crops such as watermelon and pumpkin.

Another possible explanation for the pattern we observed is that apples, cherries and blueberries have intrinsically much higher flower densities than watermelon and pumpkin. This is at least somewhat mitigated by higher recommended honeybee stocking densities [ 57, 58], but nevertheless the bee to flower ratio is likely lower in these crops. An exception to this pattern is almond, which is the earliest blooming crop in its region (February) and yet showed little evidence of limitation at the sites we sampled. One might expect pollination limitation in almond, because wild bees of most local species have not yet emerged from winter diapause. However, an entire beekeeping industry has focused on providing large numbers of honeybees for this crop, and extensive research and management effort is allocated to insure reliable pollination. In fact, during almond bloom, two thirds of all honeybee colonies in the United States are employed for California almond pollination [ 59].

Given the evidence of widespread pollinator limitation, especially in tree fruits and blueberry, our results suggest that the adoption of practices that conserve or augment wild bees, such as wildflower enhancements [ 60, 61] and the use of alternative managed pollinators [ 62, 63], is likely to be successful for increasing yields. Furthermore, the high value (over $1.5 billion for the crops in this study alone) we estimate for the contribution of wild bees to crops underscores the importance of their conservation, as well as the economic benefits that investment in conservation and augmentation strategies could bring. Increasing investment in honeybee colonies is an alternative approach to reducing pollinator limitation. Traditionally recommended stocking rates could be too low for several reasons, including the use of modern cultivars and horticultural practices that result in greater flower density per unit area, and more intensive agricultural practices, whereby fertilizer, pests and water are often less limiting than in the past. Most recommendations for honeybee stocking densities in fruit and vegetable crops were developed decades ago [ 57, 64] when production levels were lower, honeybee colonies were stronger, and feral honeybees and wild bees were more numerous. Research on optimal honeybee colony stocking density has generally not been updated to keep pace with horticultural advances (but see [ 65]), even though these changes can have significant implications for yield [ 66]. In cases where pollination is limiting, there may be little benefit to spending large amounts of money on pest control (US farms currently spend about $9 billion annually on pesticides [ 67]), fertilizer (about $23 billion [ 68]), water, or other farming practices without also finding ways to reduce pollinator limitation. Additionally, addressing pollinator limitation should increase yields and food security.

Data accessibility

Datasets used in this study are available online from the Dryad Digital Repository: https://doi.org/10.5061/dryad.hdr7sqvfj [ 69].

Authors' contributions

R.I., R.W. and J.G. conceived and designed the study. D.R.A., D.B., K.B., N.K.B., C.B., J.B., J.W.C., J.D., E.E., J.D.E., S.J.F., J.G., R.L.G., K.B.G., L.G., G.H., N.J., O.L., K.M., C.M.M., S.S.P., T.L.P.-S., S.R., N.R., L.R., K.L.W., N.M.W. and J.K.W. carried out the observations and experiments. J.R.R. designed and performed the analyses. J.R.R., R.W. and R.I. wrote the manuscript. All authors assisted with interpretation of the data and revision of the manuscript.

Competing interests

We declare we have no competing interests.

Funding

The authors acknowledge funding provided by the United States Department of Agriculture, National Institute for Food and Agriculture through the Specialty Crop Research Initiative Projects 2012-01534 (Developing Sustainable Pollination Strategies for US Specialty Crops) and PEN04398 (Determining the Role of and Limiting Factors Facing Native Pollinators in Assuring Quality Apple Production in Pennsylvania; a Model for the Mid-Atlantic Tree Fruit Industry), the State Horticultural Association of Pennsylvania, the Michigan Apple Committee, and the Michigan Cherry Committee, Operation Pollinator, the Almond Board of California (grant no.13.Poll13A), and the 2017-2018 Belmont Forum and BiodivERsA joint call for research proposals, under the BiodivScen ERA-Net COFUND programme, and with the funding organisations AEI, NWO, ECCyT and NSF.

Acknowledgements

We thank the numerous research technicians and students for their work to collect the bee and crop data for this project, including Christine Bell, Andrew Buderi, Mike Epperly, Jillian Gall, Alisa Kim, Betty Kwan, Justin Scioli, Kevin Tahara, Rachael Troyer, Kristal Watrous and Stephanie Wilson. Special thanks to the many grower collaborators and their families and staff who hosted our research at their farms and facilitated the logistics of this project, and to the project's advisory board for the input and feedback.

Footnotes

Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.5063437.

References

1.

IPBES. 2016 The assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on pollinators, pollination and food production (eds Potts S, Imperatriz-Fonseca V, Ngo H). Bonn, Germany: IPBES. Google Scholar

58.

Woodcock T. 2012Pollination in the Agricultural Landscape: Best Management Practices for Crop Pollination. Canadian Pollination Initiative (NSERC-CANPOLIN): University of Guelph. Google Scholar

59.

American Beekeeping Federation. 2018Pollination facts. See http://www.abfnet.org/page/PollinatorFacts. Google Scholar

67.

EPA. 2017 Pesticides industry sales and usage: 2008-2012 market estimates. Washington, DC: EPA. Google Scholar

68.

USDA-NASS. 2017 QuickStats online database. See https://quickstats.nass.usda.gov. Google Scholar

69.

Reilly JRet al. . 2020 Data from: Crop production in the USA is frequently limited by a lack of pollinators. Dryad Digital Repository. ( doi:10.5061/dryad.hdr7sqvfj) Google Scholar

# data[].attributes.attachment_link.title
Crop production in the USA is frequently limited by a lack of pollinators

# data[].attributes.attachment_link.description
Pollination by insects is a critical ecosystem service that is necessary for production of most crops, including those providing essential micronutrients, and is thus essential for food security [ 1]. In the USA, the production of pollinator-dependent crops is valued at over $50 billion per year [ 2, 3].

# data[].attributes.attachment_link.title
How Anthropogenic Drought Plays Out - Eos

# data[].attributes.attachment_link.description
Drought should be considered and modeled as a process, including human-nature interactions, and not merely a product of water deficit.

# data[].attributes.headline
All About American's National Mammal, The Bison

# data[].attributes.subject
All About American's National Mammal, The Bison

# data[].attributes.attachment_link.readable_text
Bison have roamed North American prairies and grasslands for thousands of years. Just recently, in 2016, they were officially named the national mammal when President Barack Obama signed the National Bison Legacy Act. According to the National Park Service, "This majestic animal joins the ranks of the bald eagle as the official symbol of our country - and much like the eagle, it's one of the greatest conservation success stories of all time."

But first: What's the difference between bison and buffalo?

Although these terms are often used interchangeably due to their similar body structure and coloring, they are actually different animals.

Both bison and buffalo are in the Bovidae family, along with sheep, goat and domestic cattle. One can spot bison from a protruding hump near their shoulders and long goatee. Their horns are shorter than a buffalo's, and they have larger heads, as well.

There are two types of buffalo: those native to Africa (African or Cape buffalo) and Asia (water buffalo), the latter of which were introduced in Europe (think buffalo-milk mozzarella). Bison are found in North America and Europe.

Gentle giants they are not

Bison are not particularly docile animals. Males can weigh up to 2,000 pounds, and females weigh up to 1,000 pounds. Although nearsighted, they have keen hearing and smell, and they can run up to 35 miles per hour. If they feel threatened, bison will show aggression and should be treated with caution.

So how did buffalo become synonymous with American bison?

There is no definitive answer why or when bison became synonymous with buffalo. According to the National Park Service, it's possible it stemmed from the French word "boeuf," meaning beef. Others suggest explorers called them buffalo because they resemble the familiar water buffalo seen throughout Europe. Another theory speculates that bison hides resemble those used to make the European buff coats commonly worn by military men at the time, inspiring the name.

The analogy continues today, even among those who raise bison.

South Dakota's Lakota Sioux refer to bison either as buffalo or with the word in their native language, tatanka. This has been the case for hundreds of years. The word, buffalo, meaning bison, is mentioned in Lakota treaties with the United States in the 19th century.

The history of the bison - and where they stand today

"In prehistoric times, millions of bison roamed North America - from the forests of Alaska and the grasslands of Mexico to Nevada's Great Basin and the eastern Appalachian Mountains. But by the late 1800s, there were only a few hundred bison left in the United States after European settlers pushed west, reducing the animal's habitat and hunting the bison to near extinction. Had it not been for a few private individuals working with tribes, states and the Interior Department, the bison would be extinct today," according to the U.S. Department of the Interior.

Today, there are roughly a half million bison in the United States. Nearly all are raised for livestock, which will be processed for meat. It is estimated that about 30,000 are managed on tribal property and federal land including some national parks.

Although their numbers have steadily increased over the past 100 years, they are still considered threatened, and bison's survival is dependent on conservation efforts. Fortunately, there are programs today, such as the Wolakota Buffalo Range , which aims to reconnect the bison with their native habitat on the Lakota Rosebud Reservation in South Dakota. Once it is fully stocked with 1,500 bison, the project will be the largest Native-owned and -managed buffalo herd.

Essential for environmental harmony

Bison are a keystone species and play a role in their biome. Keystone animals have a symbiotic relationship with other species and their environment; plants and animals are interdependent. When a keystone species is removed from its native habitat, its loss impacts the environment, resulting in an imbalance of the ecosystem.

The American bison creates favorable habitats for the variety of animals and plants of the Great Plains grasslands. Accordingly, the bison trap plant seeds within their fur resulting in the distribution of those seeds across the region as the bison move about the Plains. The bison also use their large head and horns to search for food, scooping large swaths of snow out of the way which exposes vegetation. This allows prairie dogs, another keystone species, to find spots to burrow for shelter, according to North American Nature.

The loss of a keystone species ultimately has cascading effects on humans. The threat to these habitats have lasting economic and social consequences globally. Establishing environmental harmony and biodiversity, including the reintroduction of bison to North America, is one way to preserve the fragile ecosystem for future generations.

# data[].attributes.attachment_link.authors[].name
Evelyn Red Lodge  •  Bison photography by Zach Straw

# data[].attributes.attachment_link.title
All about America's national mammal, the bison

# data[].attributes.attachment_link.description
Bison have roamed North American prairies and grasslands for thousands of years. Just recently, in 2016, they were officially named the national mammal when President Barack Obama signed the National Bison Legacy Act.

# data[].attributes.headline
10 Species Evolving Because of Climate Change

# data[].attributes.subject
10 Species Evolving Because of Climate Change

# data[].attributes.headline
The Animals that will Survive Climate Change

# data[].attributes.subject
The Animals that will Survive Climate Change

# data[].attributes.attachment_link.readable_text
"I don't think it will be the humans. I think we'll go quite early on," says Julie Gray with a laugh. I've just asked Gray, a plant molecular biologist at the University of Sheffield, which species she thinks would be the last ones standing if we don't take transformative action on climate change. Even with our extraordinary capacity for innovation and adaptability, humans, it turns out, probably won't be among the survivors.

This is partly because humans reproduce agonisingly slowly and generally just one or two at a time - as do some other favourite animals, like pandas. Organisms that can produce many offspring quickly may have a better shot at avoiding extinction.

It may seem like just a thought experiment. But discussing which species are more, or less, able to survive climate change is disturbingly concrete. As a blockbuster biodiversity report stated recently, one in every four species currently faces extinction. Much of this vulnerability is linked to climate change, which is bringing about higher temperatures, sea level rise, more variable conditions and more extreme weather, among other impacts.

You might also like:
* Could wooden buildings be a climate change solution?
* How catastrophes can change the course of humanity
* Ten simple ways to act on climate change

Some caveats are in order. While the seriousness of climate change is undeniable, it's impossible to know exactly how those effects will play out for species vulnerability, especially far into the future. Methods of forecasting vulnerability are ever evolving, while limited and inconsistent data, plus the complex interactions of policies, land-use changes, and ecological effects, mean that projections aren't set in stone. Climate change vulnerability assessments have had biases and blind spots (just as humans do more generally). (Read more about how our cognitive biases prevent climate action). Moreover, the indirect effects that are responsible for many climate change impacts on populations, such as in the food chain, are more complex to model than direct effects.

Another source of uncertainty has to do with life forms' capacity to adapt. Take ectotherms (cold-blooded animals like reptiles and amphibians), which have historically been slower to adapt to climatic change than endotherms. For one thing, they are less able to adjust their body temperatures. But there are exceptions, like the American bullfrog, which may actually find more habitable environments as a consequence of warming.

And, of course, there is an alternative: we humans could get our acts together and stop the climate crisis from continuing to snowball by adopting policies and lifestyles that reduce greenhouse gases. But for the purposes of these projections, we're assuming that's not going to happen.
Tenacious trends
Even with the uncertainties, we can make some educated guesses about broad patterns.

Heat tolerant and drought resistant plants, like those found in deserts rather than rainforests, are more likely to survive. So are plants whose seeds can be dispersed over long distances, for instance by wind or ocean currents (like coconuts), rather than by ants (like some acacias). Plants that can adjust their flowering times may also be better able to deal with higher temperatures. Jen Lau, a biologist at Indiana University Bloomington, suggests that this may give non-native plants the advantage when it comes to responding to climate change.

We also can look to history as a guide. The fossil record contains signs of how species have coped with previous climatic shifts. There are genetic clues to long-term survival too, such as in the hardy green microalgae that adapted to saltier environments over millions of years - a finding only made in September 2018 by Fatima Foflonker of Rutgers and colleagues.

Importantly, though, the uniquely devastating nature of the current human-made climate crisis means that we can't fully rely on benchmarks from the past.

"The climate change that we see in the future will differ in many ways from the climate change that we've seen in the past", notes Jamie Carr, an outreach officer for the Climate Change Specialist Group of the IUCN Species Survival Commission.

The historical record does point to the tenacity of cockroaches. These largely unloved critters "have survived every mass extinction event in history so far", says Asmeret Asefaw Berhe, a soil biogeochemist at the University of California, Merced. For instance, cockroaches adapted to an increasingly arid Australia, tens of millions of years ago, by starting to burrow into soil.

This shows two characteristics, says Robert Nasi, the director general of the Center for International Forestry Research (CIFOR): an "ability to hide and protect in buffered conditions (e.g. underground)" and a long evolutionary history, as in general "ancient species appear more resilient than younger ones". These are among the traits that, Nasi says, are linked to surviving large catastrophic events which triggered major changes in climate.

Cockroaches also tend to not be picky eaters. Having broad diets means that climate change will be less of a threat to the food sources of species that are not too fussy about their food, such as rats, opportunistic birds, and urban raccoons.

As a comparison, take an animal like the koala. Koalas eat primarily eucalyptus leaves, which are becoming less nutritious due to increasing CO2 levels in the atmosphere. As a result, climate change is increasing their risk of starvation.

As well as having a specialised diet, koalas have low genetic diversity - one reason that chlamydia has ravaged wild koala populations. These are worrying traits in terms of extinction risk. "In many cases, specialised species are those that we expect to see disappear first," says Carr. This extends to species in microhabitats like high elevation montane forests, or those in narrow ranges, like some tropical birds or small-island plants. Also vulnerable are species that depend on pristine environments.

That's compared to the "early successional" species that succeed in disturbed habitats, such as grasslands and young forest. These species "might do well under climate change because they thrive in states of change and transition", says Jessica Hellmann, who leads the Institute on the Environment at the University of Minnesota. "For example, deer (in the US) are common in suburban areas and thrive where forests have been removed or are regularly disturbed."

Species that Carr calls "mobile generalists", which can move and adapt to different environments, are likely to be more durable in the face of climate change. While this adaptability is generally positive, it might come at a cost to other parts of an ecosystem. Invasive species like cane toads, which are poisonous, have led to local extinctions of other species like quolls (carnivorous marsupials) and monitors (large lizards) in Australia. And Hellmann says that the versatility of invasive plant species "leads to the worry that, in addition to losing vulnerable species, a warmer world will be a weedier world". The weeds typically found along roadsides may be especially long-lasting in comparison with other plants.

Of course, many organisms are intrinsically less mobile. Most plants will be unable to move quickly enough to keep pace with rapid heating, although they've done so in response to the slower climatic changes of the past.
Buffer zones
The good news is that some specialised species might have a buffer known as climate change refugia: areas that are relatively protected from climate change's consequences, such as deep sea canyons. Although deep sea zones are heating up and declining in oxygen concentrations, Jonathon Stillman, a marine environmental physiologist at San Francisco State University, suggests that deep sea hydrothermal vent ecosystems, specifically, might be one bright spot in an otherwise mostly bleak situation.

"They are pretty much uncoupled from the surface of our planet and I doubt that climate change will impact them in the least," he says. "Humanity didn't even know they existed until 1977. Their energy comes from the core of our Earth rather than from the Sun, and their already extreme habitat is unlikely to be altered by changes happening at the ocean surface."

Similarly, Douglas Sheil, a tropical forest ecologist at the Norwegian University of Life Sciences, suggests that "at some point in the future the only vertebrate species surviving in Africa might be a blind cave fish deep underground". As in the deep sea hydrothermal vents, "many species remain undiscovered and thus unknown - Europe's first cave fish was only found in Germany in 2015."

Thermophiles (heat-adapted organisms) living in extreme environments like volcanic springs are also likely to be less affected by surface temperature changes. Indeed, the organisms best able to live in severe circumstances are microbes, as noted by many of the scientists I've surveyed. Computer modelling suggests that only microbes would be able to survive increasing solar intensity. Soil biogeochemist Berhe says of archaea, one of the major types of microbes, "these critters have figured out how to live in the most extreme of environments".

Not quite as tiny but also nearly indestructible are tardigrades, commonly known as water bears. Environmental physiologist Stillman enthuses: "They can survive the vacuum of outer space, extreme dehydration, and very high temperatures. If you are a Star Trek fan, you have learned about them in a sci-fi setting, but they are real creatures that live across most habitats on Earth."

The future will have not only more extreme environments, but also more urban, human-altered spaces. So "resistant species would likely be the ones that are well attuned to living in human-modified habitats such as urban parks and gardens, agricultural areas, farms, tree plantations, and so on", says Arvin C Diesmos, a herpetology curator at the Philippine National Museum of Natural History.

CIFOR's Nasi sums it up. "The winners will be very small, preferably endotherms if vertebrates, highly adaptable, omnivorous or able to live in extreme conditions."

In the words of the IUCN's Carr, "It doesn't sound like a very pretty world."

Of course, to some extent we already know what's needed to limit the bleakness of the future natural world. This includes reducing greenhouse gases; protecting biodiversity; restoring connectivity between habitats (rather than building endless dams, roads and walls); and reducing interrelated threats like pollution and land harvesting. Even species that are close to extinction, like Saiga antelopes, can be brought back from the brink with enough conservation effort. To reflect the power of sustained conservation, scientists are developing a Green List of species on the road to recovery and full health, to complement the IUCN's Red List of threatened species.

The political barriers are daunting. But scaling them, it seems, would beat surrendering the planet to the microbes.
If you liked this story, sign up for the weekly bbc.com features newsletter, called "The Essential List". A handpicked selection of stories from BBC Future, Culture, Capital, and Travel, delivered to your inbox every Friday.

# data[].attributes.attachment_link.title
The animals that will survive climate change

# data[].attributes.attachment_link.description
"I don't think it will be the humans. I think we'll go quite early on," says Julie Gray with a laugh. I've just asked Gray, a plant molecular biologist at the University of Sheffield, which species she thinks would be the last ones standing if we don't take transformative action on climate change.

# data[].attributes.attachment_link.readable_text
Hydraulic fracturing drives earthquakes in western Canada, according to research published Thursday in Science. The results defy the often-touted belief that the disposal of wastewater is the sole source of man-made earthquakes with fossil fuel extraction technique.

The small earthquakes "were always during or right after fracking, and they're also confined to a limited area," University of Calgary geophysicist, and co-author of the research paper David Eaton told NewsHour. Before fracking, the sparsely populated area in Alberta, Canada did not have a history of seismic activity.

Hydraulic fracturing involves drilling a long steel pipe - a vertical wellbore - into the earth until it hits the ground layer containing oil or natural gas. The wellbore then turns and extends horizontally, before "fracking fluid" is pumped through the pipe at high pressure. Fracking fluid, which contains water, salt, sand and additives, cracks the underground rocks to release natural gas and oil.

The U.S. Geological Survey has maintained that fracking is not the cause of most induced earthquakes. However, earthquakes have occurred in Oklahoma and nearby states as a result of wastewater disposal. Some hazardous wastewater returns to the surface, so speculators inject back into the ground in deep disposal wells.

Eaton and his co-author Xuewei Bao demonstrated hydraulic fracturing itself caused earthquakes in western Canada, by adding pressure to tectonic faults. When the pressure builds up enough, the tectonic plates slip. Other studies in Canada, including papers in Geophysical Research Letters and Seismological Research Letters had found correlations between fracking and timing of earthquakes, but Eaton and Bao's research provides a blueprint for how fracking induces seismic activity.

Most of the tremors studied by Eaton and Bao's team were too small to cause damage in the sparsely populated area. One incident registered 4.6 magnitude, though it happened after fracking and wastewater disposal had occurred. By comparison, in 2013 and 2014, the Oklahoma Geological Survey and USGS warned the state may see earthquakes as strong as 5.5-magnitude.

"I think the activities in that area are highly regulated to reduce the impact on wildlife, but nevertheless there are always concerns," said Eaton. "I think that the government regulators in western Canada are very diligent in trying to reduce the impact of these activities."

So why have Canadian researchers found fracking-related earthquakes, whereas in the U.S. wastewater disposal has been thought to be the culprit?

"I don't think we have a perfect answer yet," said Han Kao, a research scientist at the Geological Survey of Canada who wasn't involved in the study. "One possibility is that the geological setting is different."

Another possibility is that both actions trigger earthquakes, but some are measured better in one area over another.

"The neat part about this story is that [it demonstrates] that when you inject into the ground and you elevate the pore pressure, the pore pressure can prime a fault, to prime it to slip," said Kao. Even once a fracking operation has ceased, the pressure remains and can still induce seismic activity.

# data[].attributes.attachment_link.title
Earthquakes triggered by fracking, not just wastewater disposal, study finds

# data[].attributes.attachment_link.description
Hydraulic fracturing drives earthquakes in western Canada, according to research published Thursday in Science. The results defy the often-touted belief that the disposal of wastewater is the sole source of man-made earthquakes with fossil fuel extraction technique.

# data[].attributes.headline
West Virginia’s coal mine cleanup process is an underfunded ‘house of cards.’

# data[].attributes.subject
West Virginia’s coal mine cleanup process is an underfunded ‘house of cards.’

# data[].attributes.attachment_link.readable_text
Betsy Lawson was young and in love when she moved to the outskirts of Morgantown, West Virginia, in 1978. The 24-year-old and her soon-to-be husband bought 11 acres of land covered in green pastures and thriving woodland. They ate deer hunted by their neighbors* and fish caught out of nearby streams.

But in 2007, coal mining companies began buying up land near her property, seeking to turn a profit on the energy sources stored underneath the community. Lawson threw herself into trying to prevent mine construction - attending public hearings and sending letters to decision makers - but the industry won out. She remembers being told that the companies would be required to clean up the land after they were done mining it, leaving it in better condition than before.

That didn't happen. Shafer Brothers Construction Inc., the company that ran the coal mine closest to Lawson's home, filed for bankruptcy in 2014 and abandoned the mine. Today, Lawson looks out her window at an enormous mountain of excavated rocks and dirt. There are cracks in her floors from the frequent explosions companies used to blast their way down into the earth. She and her husband no longer eat local fish and deer - the streams and rivers have taken on a bright orange color from the heavy metals that drain out of the mine.

"That's what we're left with," said Lawson, who is now 67 years old. "What used to be a really attractive, traditional farming community now looks more like an industrial wasteland."

It's possible to clean up, or reclaim, abandoned mines like the ones around Lawson's home, but the costs can be mind-bogglingly high, sometimes totaling tens of millions of dollars for a single mine. In West Virginia, the question of who foots that bill has gotten messy, with bankrupt coal companies, insurers, and the state government lacking the capital to pay for full-mine reclamation.

The state's reclamation funding system is broken and needs to be improved immediately - at least that's the argument laid out in a lawsuit filed last week by the Sierra Club and West Virginian environmental groups against the U.S. Office of Surface Mining, Reclamation, and Enforcement, or OSMRE.

"All of the backstops that are supposed to be in place to make sure that at the end of the day nobody has to live next to an abandoned coal mine - all of those backstops are now threatened," said Peter Morgan, a senior attorney for the Sierra Club.

In their complaint, filed in the Southern District of West Virginia, the Sierra Club, Ohio Valley Environmental Coalition, and West Virginia Highlands Conservancy accused OSMRE of failing to require the state to improve its dangerously underfunded coal mine reclamation program. Under the 1977 Surface Mining Control and Reclamation Act, or SMCRA, states are encouraged to develop their own programs to reclaim abandoned mines, but the federal government oversees the programs and is obligated to require amendments when necessary.

Before a coal mining company begins operating in West Virginia, it must post a penal bond with an insurance company to cover a portion of the mine cleanup costs. The amount of the bond, however, is not based on an estimate of the real cleanup cost, but rather a per-acre rate of $1,000 to $5,000. "The understanding is it's always going to be smaller than the actual cost," Morgan said. "That's where the bond pool comes in." The state also maintains a bond pool, which coal mining companies pay into through a tax on every ton of coal mined. West Virginia can dip into this bond pool when mine reclamation costs are higher than the penal bond posted by a mining company. Morgan said this system is flawed, since it was created on the premise that there would always be a robust demand for coal - an assumption that has been proven false as the industry has tanked in recent years.

This growing financial gap is worrisome to environmentalists. Of the 636 mines that have been shuttered in West Virginia in recent decades, 118 still have yet to be reclaimed. And without proper funding, could they remain that way?

"The problem is now that we are seeing the permanent decline of the coal industry, the bond pool is being threatened from both sides," Morgan said, likening West Virginia's program to a house of cards. "Fewer tons of coal are being mined in West Virginia every year, so there's less and less money coming into the fund. At the same time, the risk of abandonments and the state being responsible for paying for reclamation out of the fund is just increasing."

Last year, the cracks in this funding system became starkly apparent. The coal mine operator ERP Environmental Fund Inc., which owns over 100 in-state coal mines, was financially drowning. Rather than allowing the company to go bankrupt, leaving cleanup costs to its penal bond and the bond pool, the state took matters into its own hands. "West Virginia said 'We cannot let ERP go down that path," Morgan said. "'Instead, we're going to take the extraordinary step of getting the state to appoint a special receiver to take control of the company." The appointment shielded ERP from lawsuits by creditors, and the special receiver was permitted to prioritize the cleanup of some sites over others, since state regulators acknowledged it didn't have enough money to begin reclamation of all sites at once.

In the lawsuit West Virginia was required to file in order to appoint the special receiver, the state's then-Director of Mining and Reclamation, Harold Ward, filed affidavits stating that ERP's inability to pay its debts threatened the state's own mine reclamation funding program. It was the smoking gun environmental groups needed to show that the program is teetering on the edge of disaster.

"West Virginia, in pursuing the extraordinary step of getting that special receivership, had to make certain statements on the record," Morgan said. "And so that provides all the evidence we need to bring this lawsuit."

Bright orange drainage from one of the mines near Lawson's home flowed into roadside runoff on Feb. 11, 2011. Photo courtesy Betsy Lawson

This isn't the first time alarm bells have been raised over the instability of reclamation funding in coal country. Many states across Appalachia have similar financial sets up as West Virginia, including Kentucky, Virginia, and Ohio. In 2018, the U.S. Government Accountability Office published a report recommending changes be made to bonding systems so that states aren't on the hook for reclamation funding when companies go bankrupt.

Last year, after West Virginia appointed a special receiver to ERP, the same environmental groups who filed this most recent lawsuit sued the West Virginia Department of Environmental Protection, or DEP, arguing that it had failed to notify the federal surface mining office, OSMRE, that its reclamation program was underfunded. The groups dropped last year's suit after the state DEP made the requested notification in December. However, they filed last week's lawsuit because they believe the federal agency should have required improvements to West Virginia's reclamation program after being notified of its risky funding status. Neither the West Virginia DEP nor OSMRE responded to Grist's requests for comment by the time of publication.

If the environmental groups win this most recent lawsuit and West Virginia is required to amend their mine reclamation bond program, the state will go through the time-consuming process of holding public hearings and getting federal approval for those changes. That's why Morgan of the Sierra Club wants the case to be handled urgently. While the government and courts deliberate, people like Lawson will be staring out their window at the carcass of what was once farmland, a forest, or grazing land for wild animals.

"I don't think it'll ever look like it did when we first moved here," Lawson said. "That's the curse of West Virginia, that in so many places, the coal companies just declare bankruptcy and disappear."
*Correction: This story originally misstated who caught the deer eaten by the Lawsons.

# data[].attributes.attachment_link.title
West Virginia's coal mine cleanup process is an underfunded 'house of cards.'

# data[].attributes.attachment_link.description
Betsy Lawson was young and in love when she moved to the outskirts of Morgantown, West Virginia, in 1978. The 24-year-old and her soon-to-be husband bought 11 acres of land covered in green pastures and thriving woodland.

# data[].attributes.attachment_link.readable_text
Frank Voris
November 29, 2017

Submitted as coursework for PH240, Stanford University, Fall 2017

Introduction

Fig. 1: Earthquakes per year in California. [2] (Source: F. Voris)

Since earthquake tracking began, it has always been clear that seismic events occur most commonly at the boundaries of tectonic plates. At these faults, plates moving in opposite directions push, pull, or slide against one another until the Earths crust can no longer resist these forces. Once this occurs, the effects are felt on the surface in the event of an earthquake. [1]

These boundaries where tectonic plates meet and earthquakes regularly occur are known as faults. It stands to reason that states which lie on fault lines would experience the highest propensity of earthquakes. California and Alaska, home to the world renowned San Andreas fault and Denali fault, respectively, have historically proven this axiom. In years past, they have often been at the top of earthquake frequency charts, joined by Hawaii, an island on top of a perpetually active volcano. For reference, we can see that in the last three reported years California has experienced between 100-200 earthquakes per year with a relatively uniform distribution. [2] (See Fig. 1.) In this sense, nature has been predictable and works as expected. Earthquakes happen in places of high geothermal and tectonic activity.

This held true until 2011, when occurrences of earthquakes in Oklahoma made an exponential leap compared to previous years. [3] (See Fig. 2.) What could possibly justify Oklahoma, a state that meets neither of the tectonic or geothermal criteria, being the undisputed leader in earthquakes per square mile within The United States?

Environmental Effects

Geologists attribute the environmental impact to human causes. In the years that correlate to Oklahomas earthquake boom, Hydraulic Fracturing in the area has seen the same meteoric rise. [4] Hydraulic Fracturing is a process that requires pumping high pressured liquid thousands of feet underground. The high pressure fluids then crack the shale rocks that contain natural gas making the resource far easier and more efficient to extract. The method of extraction has increased in popularity in The United States, putting thousands to work and providing relatively easy access to clean burning natural gas. Many have seen this boom as having a positive impact, and indeed natural gas produces fewer emissions than the burning of coal or oil. [5] Information regarding Oklahomas earthquake epidemic paints a much darker and less environmentally friendly picture of Hydraulic Fracturing.

Fig. 2: Earthquakes per year in Oklahoma. [3] (Source: F. Voris)

The detriment to the environment is thought to come not from the fracking process itself, but from the methods used to dispose of waste from the extraction. [2] After pumping the high pressure liquid into the Earth it becomes contaminated with metals, the oil/gas itself, and the hydraulic fluid used to reach ground-breaking pressures. Once this water is retrieved it is not safe for drinking, or any other industrial purpose. In order to dispose of this waste, as of 2014, over 10,000 wastewater sites have been constructed in Oklahoma alone. These sites pump the wastewater below the water table to be disposed of forever. In doing so, they increase the subterranean pressure and disrupt the delicate equilibrium of inactive faults well below Oklahomas surface inducing seismic events. [2] Earthquake maps support this theory, as the location of seismic events are concentrated in locations where dormant faults meet wastewater disposal sites. [2]

Conclusion

These events have been noticed by the United States Geological Service, and they predict that serious harm might come from mans alteration of the Earths crust. While many small tremors might not get the attention of the population or its lawmakers, the continued escalation of the threat will surely be noticed. The stakes became clear on September 3rd, 2016 when a 5.8 magnitude Earthquake struck Pawnee, Oklahoma. This was the strongest earthquake in Oklahoma history and the USGS predicts a 40% chance that another major earthquake will strike Oklahoma in 2017.

© Frank Voris. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] H. Kanamori and E. E. Brodsky, "The Physics of Earthquakes," Rep. Prog. Phys. 67, 1429 (2004).

[2] E. Hand, "Injection Wells Blamed in Oklahoma Earthquakes," Science 345, 13 (2014).

[3] J. Schlaffer, "Is the use of Hydraulic Fracturing by the Energy Industry Causing More Frequent Earthquakes in Oklahoma?," Scholars Strategy Network, (2013).

[4] K. M. Keranen et al., "Sharp Increase in Central Oklahoma Seismicity Since 2008 Induced By Massive Wastewater Injection," Science 345, 448 (2014).

[5] H. Boudet et al., "Fracking Controversy and Communication: Using National Survey Data to Understand Public Perceptions of Hydraulic Fracturing," Energy Policy 65, 57 (2014)

# data[].attributes.attachment_link.title
Analysis of Fracking-Induced Seismic Events

# data[].attributes.attachment_link.description
Fig. 1: Earthquakes per year in California. [2] (Source: F. Voris) Since earthquake tracking began, it has always been clear that seismic events occur most commonly at the boundaries of tectonic plates. At these faults, plates moving in opposite directions push, pull, or slide against one another until the Earths crust can no longer resist these forces.

# data[].attributes.headline
Mount Nyiragongo just erupted—here's why it's one of Africa's most dangerous volcanoes

# data[].attributes.subject
Mount Nyiragongo just erupted—here's why it's one of Africa's most dangerous volcanoes

# data[].attributes.attachment_link.readable_text
A structure is surrounded by lava on May 23, 2021, during the eruption of Mount Nyiragongo, which can be seen in the background. A river of lava came to a halt on the outskirts of Goma, sparing the city in the eastern Democratic Republic of the Congo from disaster after the nighttime eruption prompted thousands of residents to evacuate.

Photograph by Moses Sawasawa, AFP via Getty Images

Lava from the recent eruption stopped just short of the city of Goma in the Democratic Republic of the Congo. But geologic factors and inconsistent monitoring make the volcano a perpetual threat.

Mount Nyiragongo is rarely calm. The mountainous volcano in the east of the Democratic Republic of the Congo (DRC) is one of the few places in the world to feature a persistent lake of lava bubbling within its summit crater.

And late on May 22, local time, things abruptly escalated: Fractures opened up in the volcano's rocky sides, spilling fast-moving lava down its slopes. Some of it headed toward the city of Goma, a metropolis just six miles away that's home to around 1.5 million people. The night sky shimmered with a crimson hue as lava, sometimes piling up to three stories high, speedily invaded the streets of several villages surrounding Goma and swallowed any buildings it encountered, setting them ablaze. As of this writing, there have been 15 confirmed casualties, a number expected to rise in the coming days.

Two of Nyiragongo's recent eruptions, in 1977 and 2002, were full-blown disasters. In 1977, estimates suggest somewhere between 600 and 2,000 people were killed by lava flows. In 2002, molten rock destroyed up to a fifth of Goma, leaving 120,000 people homeless and killing around 250 people through carbon dioxide asphyxiation, burns, and the lava-triggered explosion of a gas station.

These past disasters have left volcanologists nervous every time Nyiragongo shows signs of life. "It's one of the most dangerous volcanoes in Africa," says Benoît Smets, a geohazards expert at the Royal Museum for Central Africa in Tervuren, Belgium.

Nyiragongo's deadly reputation is due to a perfect storm of factors. Because of the geologic complexities of the region, its lava is remarkably fluid, able to move at up to 40 miles an hour. Eruptions can also send large amounts of lethal carbon dioxide gas to the surface. That's extremely worrying, since millions of people live in the volcano's shadow.

Debris engulfs buildings in Bushara village, near the city of Goma in the Democratic Republic of the Congo, on May 23, 2021, after Mount Nyiragongo erupted.

Photograph by Justin Katumwa, AFP via Getty Images

Add in the region's political instability and bouts of conflict, and Nyiragongo is a profoundly difficult volcano to monitor. Despite the best efforts of the Goma Volcano Observatory-set up in the eponymous city in 1986-no clear warning signals were detected prior to its latest eruption.

Fuel their curiosity with your gift

With all these factors in play, the fiery mountain is capable of producing "the kind of eruptions you really fear," says Corentin Caudron, a volcanologist at the Institute of Earth Sciences in Grenoble, France.

A tectonic rift

Nyiragongo, whose peak stands 11,400 feet above the DRC's Virunga National Park, owes its existence to two things. One is the leisurely geologic fragmentation of Eastern Africa. A strip of land from the Red Sea down to Mozambique is being pulled asunder, with the Nubian plate to the northwest and the Somalian plate to the southeast moving in opposite directions by a few inches every decade. This tectonic divide is known as the East African Rift.

Among other things, this rifting action makes pathways for magma to rise and create volcanoes. What's more, a plume of superheated but solid mantle material is rising from considerable depth to interact with the underbellies of the tectonic plates. This combination of rifting and pluming creates some strange magmatic concoctions, says Christopher Jackson, a geologist at the University of Manchester in the U.K.

Most magma has a decent amount of silica in it, a compound that acts as a sort of skeleton in molten rock. The less silica you have, the less viscous or goopy the lava is once it erupts. Basaltic magma, the stuff erupting out of Iceland's Reykjanes Peninsula right now, has a low proportion of silica in it, making it fairly runny, but on a flat surface it can easily be outwalked.

Not so for Nyiragongo's molten matter: Its lava has such a deficit of silica that it zips across the ground, especially if the lava is erupting at a high rate. If the lava erupts from a high elevation, the volcano's steep slope may give it an additional speed boost.

A person at the border point known as "Petite Barriere" in Gisenyi, Rwanda, on May 23, 2021, carries a suitcase on their head as people flee from Goma, Democratic Republic of Congo, after Mount Nyiragongo erupted.

Photogrpah by Simon Wohlfahrt, AFP via Getty Images

The volcano's magma is also particularly rich in carbon dioxide, an invisible, odorless gas. This gas often quietly exudes to the surface via aquifers above deep-seated bodies of degassing magma. Being denser than air, the gas gathers unnoticed in low-lying areas. Locals refer to it as mazuku, or "evil wind."

"We have many people die because of mazuku every year in the area," Smets says. If carbon dioxide-rich magma is tapped by Nyiragongo, dangerous volumes of the gas may also gush out of fissures and flood areas rather suddenly.

A volcanic ambush

Eruptions at Nyiragongo generally transpire when the pressure of accumulating magma or an earthquake forces open fissures in the sides of the mountain, leading to the catastrophic draining of the lava lake or the eruption of magma stored deeper down.

But like the volcanoes that make them, individual eruptions have their own unique behaviors and properties, and no two are identical. Monitoring volcanoes for signs of upcoming paroxysms is therefore fraught with difficulties, and Nyiragongo's latest flare-up is a perfect example of these challenges.

Between eruptions, Nyiragongo's summit crater tends to fill up with magma, and it has been doing just that since the 2002 eruption. In 2016, a second vent opened at the summit. In 2020, volcanologists flown in by UN peacekeepers, who shielded the scientists from armed rebels in the area, noticed the lava lake was filling up faster than ever. A worrying sight, but scientists can't be sure whether the height of the lava lake is an indicator of the volcano's readiness to erupt.

On May 10, 2021, the Goma Volcano Observatory detected an uptick in seismic activity at the summit. This was perhaps suggestive of magma moving about at shallow depths, but it was not a surefire harbinger of an upcoming eruption.

The observatory's efforts to keep an eye on Nyiragongo have been somewhat stymied as of late. Some of its seismic stations had been subjected to theft and vandalism, with the risk of violence leaving many of them unrepaired. The observatory also lost financial support from the World Bank last year amid allegations of embezzlement.

Consequently, for several months, remote sensors lacked an internet connection, and regular on-site measurements of the volcano were not possible. Despite these ongoing issues, the observatory, with a small budget from the DRC government, and in cooperation with other international partners, kept up its efforts to monitor Nyiragongo.

But in the end, the volcano erupted unexpectedly, providing no clear geologic hints that it was about to blow. "There was absolutely no precursor for this eruption," Smets says. "Nobody could have detected this eruption" in advance.

This weekend's eruption surprised a city haunted by Nyiragongo's past infernos. Down to luck alone, the lava missed Goma. By Sunday morning, the eruption had lost its intensity. The lava stopped less than 1,000 feet from Goma's edge, leaving behind a frozen, hissing river of volcanic rock.

Even so, tragedy struck 17 nearby villages, which suffered incursions of lava, leading to the loss of hundreds of houses, a school, three health-care centers, and a water pipeline. As of this writing, two people burned to death, nine died in a traffic collision during the chaotic evacuation, and four prisoners were killed as they attempted to escape their cells.

A future of fire

Nyiragongo is still making a lot of seismic noise, and some significant earthquakes are shaking the region, hinting at turbulence below. But scientists don't know whether another eruption could happen soon.

This past weekend is the first time that an expansive suite of monitoring equipment-as opposed to the small assortment of seismic stations in the past-has been up and running during a Nyiragongo eruption. That's great news for those wishing to study the current geologic activity, but without older data to compare it with, the recent volcanic activity is difficult to interpret. But, Caudron says, these records will be invaluable to scientists working to understand the churnings of the volcano in the run up to the next eruption.

Nyiragongo will certainly erupt again, eventually. Lava could tear through Goma next time. If the area's Lake Kivu is disturbed by major underwater volcanic activity, significant quantities of carbon dioxide may flood its shores. And if the magma moves elsewhere below ground, a new volcanic vent could open up in the middle of the city.

The hazards are plentiful and omnipresent around this hyperactive volcano. Goma, along with Gisenyi-a Rwandan city contiguous with Goma-are in near-perpetual peril.

But work is continuously being done to bolster scientists' understanding, from determining how often it erupts to mapping out the likely future paths of lava flows, says Matthieu Kervyn, a natural hazards expert at the Free University of Brussels in Belgium.

Whatever the science reveals, many of the city's residents likely can't or won't move to somewhere safer, even those who live in the eventual paths of the volcano's future flows. Should lava once again slither through the streets of Goma, it could inflict great harm and lasting trauma on millions of people.

But perhaps the recent close encounter with widespread destruction will spark a renewed mitigation effort, leading to more robust scientific work on the ground, more active monitoring, and renewed city planning in the most at-risk areas.

# data[].attributes.attachment_link.title
Mount Nyiragongo just erupted-here's why it's one of Africa's most dangerous volcanoes

# data[].attributes.attachment_link.description
Lava from the recent eruption stopped just short of the city of Goma in the Democratic Republic of the Congo. But geologic factors and inconsistent monitoring make the volcano a perpetual threat.

# data[].attributes.headline
Widening and weakening of the Hadley circulation under global warming

# data[].attributes.subject
Widening and weakening of the Hadley circulation under global warming

# data[].attributes.attachment_link.readable_text
Yongyun Hu is a professor in the Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University. He received his BS from Sun Yat-sen University, MS from Texas A&M University, and Ph.D. from the University of Chicago. He had worked as a postdoctoral scientist at the University of Washington as well as Columbia University and NASA-GISS. He has broad research interests in present, past, and planetary climates.

# data[].attributes.attachment_link.title
Widening and weakening of the Hadley circulation under global warming

# data[].attributes.attachment_link.description
Yongyun Hu is a professor in the Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University. He received his BS from Sun Yat-sen University, MS from Texas A&M University, and Ph.D. from the University of Chicago. He had worked as a postdoctoral scientist at the University of Washington as well as Columbia University and NASA-GISS.

# data[].attributes.headline
Climate change: Where we are in seven charts and what you can do to help

# data[].attributes.subject
Climate change: Where we are in seven charts and what you can do to help

# data[].attributes.attachment_link.readable_text
Climate change is set to cause major changes across the world: sea levels will rise, food production could fall and species may be driven to extinction.

The UN has warned that the world needs to limit climate change to below 1.5C above pre-industrial levels. But scientists say that keeping to the 1.5C target will require "rapid, far-reaching and unprecedented changes" in all aspects of society.

So how warm has the world got and what can we do about it?

The global average temperature for the first 10 months of 2018 was 0.98C above the levels of 1850-1900, according to five independently maintained global data sets.

(If you can't see this chart tap or click here)

The 20 warmest years on record have been in the past 22 years, with 2015-2018 making up the top four, the WMO says.

If this trend continues, temperatures may rise by 3-5C by 2100.

One degree may not sound like much, but, according to the IPCC, if countries fail to act, the world will face catastrophic change - sea levels will rise, ocean temperatures and acidity will increase and our ability to grow crops, such as rice, maize and wheat, would be in danger.

Almost 400 all-time high temperatures were set in the northern hemisphere during the summer of 2019.

Records were broken in 29 countries for the period between 1 May and 30 August. A third of the all-time high temperatures were in Germany, followed by France and the Netherlands.

These European records were set amid heatwaves across the continent that sent temperatures soaring in June and July.

Over the period shown on the map below (May to August 2019), the yellow dots show where a heat record was broken on a given date, pink indicates places that were the hottest they had ever been in the month shown, and dark red represents a place that was the hottest since records began.

More than 30 all-time records were broken in the US, according to the Berkeley Earth data. In Japan, where 11 people died as a result of the summer heatwave, 10 all-time temperature highs were set.

If we add up all the promises to cut emissions made by countries that are party to the Paris climate agreement, the world would still warm by more than 3C by the end of this century.

Over the past few years, climate scientists have shifted the definition of what they believe is the "safe" limit of climate change.

For decades, researchers argued the global temperature rise must be kept below 2C by the end of this century to avoid the worst impacts.

Countries signing up to the Paris agreement pledged to keep temperatures "well below 2C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5C".

But scientists now agree that we actually need to keep temperature rises to below 1.5C.

The countries emitting the most greenhouse gases by quite a long way are China and the US. Together they account for more than 40% of the global total, according to 2017 data from the European Commission's Joint Research Centre and PBL Netherlands Environmental Assessment Agency.

US environmental policy has shifted under the Trump administration, which has pursued a pro-fossil fuels agenda.

President Donald Trump has begun the process of withdrawing the US from the Paris climate change agreement.

Mr Trump said the deal struck in 2015 would disadvantage US businesses and workers.

And it's the faster-growing cities that are most at risk, including megacities like Lagos in Nigeria and Kinshasa in the Democratic Republic of Congo.

Some 84 of the world's 100 fastest-growing cities face "extreme" risks from rising temperatures and extreme weather brought on by climate change.

The extent of Arctic sea ice has dropped in recent years. It reached its lowest point on record in 2012.

The Arctic Ocean may be ice-free in the summer as soon as the 2050s, unless emissions are reduced, the committee has said.

The extent of Arctic sea ice in 2019 was tied with 2007 and 2016 as the second lowest on record. The maximum extent, reached in March 2019, was tied with 2007 as the seventh lowest in the 40-year satellite record.

While governments need to make big changes - individuals can play a role too.

Scientists say we all have to make major changes to our lifestyles, in order to avoid severely damaging climate change.

The IPCC says we need to: buy less meat, milk, cheese and butter; eat more locally sourced seasonal food - and throw less of it away; drive electric cars but walk or cycle short distances; take trains and buses instead of planes; use videoconferencing instead of business travel; use a washing line instead of a tumble dryer; insulate homes; demand low carbon in every consumer product.

Scientists say we ought to eat less meat because of the carbon emissions the meat industry produces, as well as other negative environmental impacts.

For example, beef cattle raised on deforested land produces 12 times more greenhouse gas emissions than those reared on natural pastures.

Crucially, the analysis shows that meat with the lowest environmental impact still creates more greenhouse gas emissions than growing vegetables and cereal crops in the least environmentally-friendly way.

By Nassos Stylianou, Clara Guibourg, Daniel Dunford, Lucy Rodgers, David Brown and Paul Rincon

Correction 24 February 2020: A previous version of this story said that "the single biggest way to reduce your environmental impact on the planet is to modify your diet to include less meat". This has been amended to now refer to "one of the biggest," taking account of different individual lifestyles and circumstances. We have also replaced the in-line link with a research article on 'The global impacts of food production'.

# data[].attributes.attachment_link.title
Climate change: Where we are in seven charts and what you can do to help

# data[].attributes.attachment_link.description
We look at how hot the world has got and what can we can all do to tackle global warming.

# data[].attributes.headline
Climate Change Indicators: Weather and Climate

# data[].attributes.subject
Climate Change Indicators: Weather and Climate

# data[].attributes.attachment_link.readable_text
Rising global average temperature is associated with widespread changes in weather patterns. Scientific studies indicate that extreme weather events such as heat waves and large storms are likely to become more frequent or more intense with human-induced climate change. This chapter focuses on observed changes in temperature, precipitation, storms, floods, and droughts.

Why does it matter?

Long-term changes in climate can directly or indirectly affect many aspects of society in potentially disruptive ways. For example, warmer average temperatures could increase air conditioning costs and affect the spread of diseases like Lyme disease, but could also improve conditions for growing some crops. More extreme variations in weather are also a threat to society. More frequent and intense extreme heat events can increase illnesses and deaths, especially among vulnerable populations, and damage some crops. While increased precipitation can replenish water supplies and support agriculture, intense storms can damage property, cause loss of life and population displacement, and temporarily disrupt essential services such as transportation, telecommunications, energy, and water supplies.

Summary of Key Points

U.S. and Global Temperature. Average temperatures have risen across the contiguous 48 states since 1901, with an increased rate of warming over the past 30 years. Nine of the top 10 warmest years on record have occurred since 1998. Average global temperatures show a similar trend, and all of the top 10 warmest years on record worldwide have occurred since 2005. Within the United States, temperatures in parts of the North, the West, and Alaska have increased the most.

Seasonal Temperature. As the Earth warms overall, average temperatures increase throughout the year, but the increases may be larger in certain seasons than in others. Since 1896, average winter temperatures across the contiguous 48 states have increased by nearly 3°F. Spring temperatures have increased by about 2°F, while summer and fall temperatures have increased by about 1.5°F.

High and Low Temperatures. Many extreme temperature conditions are becoming more common. Since the 1970s, unusually hot summer days (highs) have become more common over the last few decades in the United States. Unusually hot summer nights (lows) have become more common at an even faster rate. This trend indicates less "cooling off" at night. Although the United States has experienced many winters with unusually low temperatures, unusually cold winter temperatures have become less common-particularly very cold nights (lows). Record-setting daily high temperatures have become more common than record lows.

Heat Waves. Heat waves are occurring more than they used to in major cities across the United States. Heat waves are occurring three times more often than they did in the 1960s-about six per year compared with two per year. The average heat wave season is 49 days longer, and individual heat waves are lasting longer and becoming more intense.

U.S. and Global Precipitation. Total annual precipitation has increased over land areas in the United States and worldwide. Since 1901, precipitation has increased at an average rate of 0.2 inches per decade over the contiguous 48 states. However, shifting weather patterns have caused certain areas, such as the Southwest, to experience less precipitation than usual.

Heavy Precipitation. In recent years, a higher percentage of precipitation in the United States has come in the form of intense single-day events. The prevalence of extreme single-day precipitation events remained fairly steady between 1910 and the 1980s but has risen substantially since then. Nationwide, nine of the top 10 years for extreme one-day precipitation events have occurred since 1996. The occurrence of abnormally high annual precipitation totals (as defined by the National Oceanic and Atmospheric Administration) has also increased.

Tropical Cyclone Activity. Tropical storm activity in the Atlantic Ocean, the Caribbean, and the Gulf of Mexico has increased during the past 20 years. Storm intensity, a measure of strength, duration, and frequency, is closely related to variations in sea surface temperature in the tropical Atlantic and has risen noticeably during that time. However, changes in observation methods over time make it difficult to know for sure whether a longer-term increase in storm activity has occurred. Records collected since the late 1800s suggest that the actual number of hurricanes per year has not increased.

River Flooding. Increases and decreases in the frequency and magnitude of river flood events vary by region. Floods have generally become larger across parts of the Northeast and Midwest and smaller in the West, southern Appalachia, and northern Michigan. Large floods have become more frequent across the Northeast, Pacific Northwest, and parts of the northern Great Plains, and less frequent in the Southwest and the Rockies.

Drought. Average drought conditions across the nation have varied over time. The 1930s and 1950s saw the most widespread droughts, while the last 50 years have generally been wetter than average. Specific trends vary by region, as the West has generally experienced more drought while the Midwest and Northeast have become wetter. A more detailed index developed recently shows that over the period from 2000 through 2020, roughly 20 to 70 percent of the U.S. land area experienced conditions that were at least abnormally dry at any given time. However, this index has not been in use for long enough to compare with historical drought patterns.

A Closer Look: Temperature and Drought in the Southwest. The southwestern United States is particularly sensitive to changes in temperature and thus vulnerable to drought, as even a small decrease in water availability in this already arid region can stress natural systems and further threaten water supplies. Several measures indicate persistent and more severe drought conditions in recent years.

# data[].attributes.attachment_link.title
Climate Change Indicators: Weather and Climate | US EPA

# data[].attributes.headline
The tropics are expanding, and climate change is the primary culprit

# data[].attributes.subject
The tropics are expanding, and climate change is the primary culprit

# data[].attributes.attachment_link.readable_text
Earth's tropics are expanding poleward and that expansion is driven by human-caused changes to the ocean, according to new research.

The tropics wrap around Earth's middle like a warm, wet belt. This part of the globe gets the most direct sunlight throughout the year and is characterized by high average temperatures and heavy rainfall. In contrast to the tropics' lush interior, however, this region's edges are hot and parched.

Scientists have noticed for the past 15 years that these arid bands are expanding toward the poles into regions like the Mediterranean, southern Australia and southern California. Interestingly, these dry areas have expanded more in the Southern Hemisphere than the Northern Hemisphere and researchers have struggled to pinpoint exactly what is driving the trend.

A new study in AGU's , Journal of Geophysical Research: Atmospheres argues that the failure to agree on an exact mechanism has been, in part, because most researchers have been looking in the wrong place. The new study found tropical expansion is driven primarily by ocean warming caused by climate change rather than direct changes to the atmosphere. A bigger shift is happening in the Southern Hemisphere because it has more ocean surface area, according to the new study.

Tropical expansion could have profound economic and social implications: the process could shift storm paths and cause more severe wildfires and droughts in places like California and Australia that are already water-stressed.

The new findings provide the clearest evidence yet that tropical expansion is in fact primarily driven by climate change, according to the study authors. While natural long-term climate fluctuations contribute to the observed trends, these variations alone cannot explain the extent to which expansion has already occurred.

This means, the authors argue, that climate change might have already significantly contributed to tropical expansion, especially in the ocean-dominated Southern Hemisphere.

"We demonstrate that the enhanced subtropical ocean warming is independent from the natural climate oscillations," said Hu Yang, a climate scientist at the Alfred Wegner Institute in Bremerhaven, Germany and lead author of the new study. "This is a result of global warming."
A disconcerting phenomenon
A 2006 paper published in the journal Science announced a troubling finding: in some parts of the world, the tropics were expanding. Researchers have attempted to figure out the culprit ever since that paper was published. Scientists estimate from satellite observations that this widening is happening at a rate of 0.25 to 0.5 degrees latitude per decade. But without pinpointing a root cause, they cannot accurately model how quickly the expansion will occur in the future or what regions it will impact.

Some researchers have suggested greenhouse gas emissions, ozone depletion and aerosols in the atmosphere are driving the expansion. But climate models using these variables to explain the expansion consistently underestimate the speed of the shift and do not account for why expansion is happening in some regions but not others. This has led some researchers to theorize that tropical expansion can simply be explained by natural oscillations in Earth's climate. But natural variation does not quite fit the patterns scientists have already observed.
Ocean versus atmosphere
Yang and colleagues began to take notice of tropical expansion in 2015, when analyzing ocean currents that carry warm water toward the poles. This got them thinking: what if tropical expansion was driven not by changes in the atmosphere, but changes in the ocean?

Because the ocean and atmosphere are highly connected systems, it is often difficult to tell which is driving the other, Yang said. In the new study, Yang and his colleagues analyzed water temperatures in the major ocean gyres, large circular ocean currents that carry warm water toward the poles and cold water toward the equator. They used satellite observations of sea surface temperature between 1982, the year observations began, and 2018, and compared these observations to data on the expanding tropics that stretches back to 1979.

They found excess heat building up in the subtropical oceans since global warming began in the mid-1800s has driven tropical edges and ocean gyres toward the poles. When the researchers compared movement of the ocean gyres to tropical expansion, they found the two phenomena matched: tropical expansion was happening in places where the ocean gyres were moving poleward.

"I actually am really impressed with this paper," said Kristopher Karnauskas, associate professor in the Department of Atmospheric and Oceanic Sciences at the University of Colorado Boulder who was not connected to the new study. "There really aren't a lot of papers out there that really investigate the role of the ocean in the tropical expansion problem."

# data[].attributes.attachment_link.keywords[]
climate; global warming; environmental awareness; environmental issues; earth science; oceanography; geography; water

# data[].attributes.attachment_link.title
The tropics are expanding, and climate change is the primary culprit

# data[].attributes.attachment_link.description
Earth's tropics are expanding poleward and that expansion is driven by human-caused changes to the ocean, according to new research. The tropics wrap around Earth's middle like a warm, wet belt. This part of the globe gets the most direct sunlight throughout the year and is characterized by high average temperatures and heavy rainfall.

# data[].attributes.headline
Thousands of leaking barrels containing insecticide DDT found in dumping ground off LA coast

# data[].attributes.subject
Thousands of leaking barrels containing insecticide DDT found in dumping ground off LA coast

# data[].attributes.attachment_link.title
Scientists ‘incredulous’ after thousands of leaking insecticide barrels found in ocean dumping ground

# data[].attributes.attachment_link.description
Researchers are concerned about the impact on the food chain after finding at least 27,000 DDT barrels, some of them leaking, on the ocean floor off the coast of Los Angeles.

# data[].attributes.headline
How Three States Are Repairing The Failing Recycling System

# data[].attributes.subject
How Three States Are Repairing The Failing Recycling System

# data[].attributes.attachment_link.readable_text
"We should reduce first and only then recycle," said David Allaway, senior policy analyst with the ... [+]
getty

States are reviving America's broken recycling system by emphasizing reducing and reusing first. And when it comes to recycling, they're holding the producers of material responsible for its fate.

"Right now producers are not doing enough to help communities make recycling more effective," said Sarah Nichols of the Natural Resources Council of Maine, "and part of the reason is because they're not the ones responsible for cleaning up the mess created by their businesses.

"They don't currently internalize any of those costs, and rather they externalize those on our municipalities and taxpayers, who have little to no control over this waste."

Representatives from three states highlighted their innovations last month in a webinar hosted by the The Environmental and Energy Study Institute:
Maine
Maine's legislature is considering tackling what Nichols calls the "tsunami of packaging materials" with a bill that would hold the producers of packaging responsible for its fate. "By packaging I mean things like cereal boxes and Amazon packaging and yogurt tubs, takeout containers, boxes, flexible packaging-basically all the stuff that ends up in your household," Nichols said.

If LD 1541 passes, producers will pay fees to a new stewardship organization for the packaging they sell to consumers in Maine. The organization would funnel the fees to the municipalities that handle the waste.

"I like to think that the stewardship organization connects the waste makers to the waste takers with oversight by the state," Nichols said, "and this oversight helps make sure we have transparency and accountability within the system and not necessarily letting the fox watch the henhouse."
Oregon
Advocates in Oregon are pushing for the Plastic Pollution and Recycling Modernization Act (SB 582A), which would require materials producers to help pay for the effort to collect and transport their materials for recycling. As in Maine, producers would have more incentive to promote reducing and reusing. The bill would also harmonize the jumble of local regulations with a single statewide list of recyclables based on economic and environmental benefits.

"It's a shared responsibility proposal that would continue the parts of our system that work well and improve the parts that don't," said David Allaway, senior policy analyst with the Oregon Department of Environmental Quality.
Iowa
Since 1990 Iowa has diverted an estimated 4 million tons of materials from the landfill-and saved $120 million-through the Iowa Waste Exchange, a program that pairs people who are seeking materials-everything from stuffed animals to industrial sludge-with people trying to get rid of them, said Jennifer Wright, a supervisor with the Iowa Department of Natural Resources. The reuse program is funded by about $400,000 per year in landfill tipping fees.

"Based on the fact that we provide them about an average of $400,000 per year and yet they are able to bring an annual savings back to iowa around $3 million dollars, we were able to determine that they have about a 650 percent return on that investment," Wright said.

MORE FROM FORBES Three Reasons Recycling Is Failing

... Read More

# data[].attributes.attachment_link.keywords[]
plastic pollution and recycling modernization act (sb 582a)

# data[].attributes.attachment_link.keywords[]
environmental and energy study institute

# data[].attributes.attachment_link.title
How Three States Are Repairing The Failing Recycling System

# data[].attributes.attachment_link.description
States are reviving America's broken recycling system by emphasizing reducing and reusing first. And when it comes to recycling, they're holding the producers of material responsible for its fate.

# data[].attributes.headline
Toxic “Dead Zone” – Surge in Nitrogen Has Turned Sargassum Into the World’s Largest Harmful Algal Bloom

# data[].attributes.subject
Toxic “Dead Zone” – Surge in Nitrogen Has Turned Sargassum Into the World’s Largest Harmful Algal Bloom

# data[].attributes.attachment_link.readable_text
For centuries, pelagic Sargassum, floating brown seaweed, have grown in low nutrient waters of the North Atlantic Ocean, supported by natural nutrient sources like excretions from fishes and invertebrates, upwelling and nitrogen fixation. Using a unique historical baseline from the 1980s and comparing it to samples collected since 2010, researchers from Florida Atlantic University's Harbor Branch Oceanographic Institute and collaborators have discovered dramatic changes in the chemistry and composition of Sargassum, transforming this vibrant living organism into a toxic "dead zone."

Their findings, published in Nature Communications, suggest that increased nitrogen availability from natural and anthropogenic sources, including sewage, is supporting blooms of Sargassum and turning a critical nursery habitat into harmful algal blooms with catastrophic impacts on coastal ecosystems, economies, and human health. Globally, harmful algal blooms are related to increased nutrient pollution.

Sargassum, floating brown seaweed, has grown in low nutrient waters of the North Atlantic Ocean for centuries. Scientists have discovered dramatic changes in the chemistry and composition of Sargassum, transforming this vibrant living organism into a toxic "dead zone." Credit: Brian Lapointe, Ph.D.

The study, led by FAU Harbor Branch, in collaboration with the University of South Florida, Woods Hole Oceanographic Institution, the University of Southern Mississippi, and Florida State University, was designed to better understand the effects of nitrogen and phosphorus supply on Sargassum. Researchers used a baseline tissue data set of carbon (C), nitrogen (N) and phosphorus (P) and molar C:N:P ratios from the 1980s and compared them with more recent samples collected since 2010.

Results show that the percentage of tissue N increased significantly (35 percent) concurrent with a decrease in the percentage of phosphorus (42 percent) in Sargassum tissue from the 1980s to the 2010s. Elemental composition varied significantly over the long-term study, as did the C:N:P ratios. Notably, the biggest change was the nitrogen:phosphorus ratio (N:P), which increased significantly (111 percent). Carbon:phosphorus ratios (C:P) also increased similarly (78 percent).

"Data from our study supports not only a primary role for phosphorus limitation of productivity, but also suggests that the role of phosphorus as a limiting nutrient is being strengthened by the relatively large increases in environmental nitrogen supply from terrestrial runoff, atmospheric inputs, and possibly other natural sources such as nitrogen fixation," said Brian Lapointe, Ph.D., senior author, a leading expert on Sargassum and a research professor at FAU Harbor Branch.

A total of 488 tissue samples of Sargassum were collected during various research projects and cruises in the North Atlantic basin between 1983-1989 and more recently between 2010-2019, and included seasonal sampling offshore Looe Key reef in the lower Florida Keys (1983 and 1984) and a broader geographic sampling (1986 and 1987) offshore the Florida Keys, Gulf Stream (Miami, Charleston and Cape Fear), and Belize, Central America. Oceanic stations included the northern, central and southern Sargasso Sea.

The highest percentage of tissue N occurred in coastal waters influenced by nitrogen-rich terrestrial runoff, while lower C:N and C:P ratios occurred in winter and spring during peak river discharges. The overall range for N:P ratios was 4.7 to 99.2 with the highest mean value in western Florida Bay (89.4) followed by locations in the Gulf of Mexico and Caribbean. The lowest N:P ratios were observed in the eastern Caribbean at St. Thomas (20.9) and Barbados (13.0).

Because of anthropogenic emissions of oxides of nitrogen (NOx), the NOx deposition rate is about five-fold greater than that of pre-industrial times largely due to energy production and biomass burning. Production of synthetic fertilizer nitrogen has increased nine-fold, while that of phosphate has increased three-fold since the 1980s contributing to a global increase in N:P ratios. Notably, 85 percent of all synthetic nitrogen fertilizers have been created since 1985, which was shortly after the baseline Sargassum sampling began at Looe Key in 1983.

"Over its broad distribution, the newly-formed Great Atlantic Sargassum Belt can be supported by nitrogen and phosphorus inputs from a variety of sources including discharges from the Congo, Amazon and Mississippi rivers, upwelling off the coast of Africa, vertical mixing, equatorial upwelling, atmospheric deposition from Saharan dust, and biomass burning of vegetation in central and South Africa," said Lapointe.

Long-term satellite data, numerical particle-tracking models, and field measurements indicate that the Great Atlantic Sargassum Belt has recurred annually since 2011 and extended up to 8,850 kilometers from the west coast of Africa to the Gulf of Mexico, peaking in July 2018.

"Considering the negative effects that the Great Atlantic Sargassum Belt is having on the coastal communities of Africa, the Caribbean, Gulf of Mexico and South Florida, more research is urgently needed to better inform societal decision-making regarding mitigation and adaptation of the various terrestrial, oceanic, and atmospheric drivers of the Sargassum blooms," said Lapointe.

Sargassum removal from Texas beaches during earlier, less severe inundations was estimated at $2.9 million per year and Florida's Miami-Dade County alone estimated recent removal expenses of $45 million per year. The Caribbean-wide clean-up in 2018 cost $120 million, which does not include decreased revenues from lost tourism. Sargassum strandings also impact marine life and cause respiratory issues from the decaying process and other human health concerns, such as increased fecal bacteria.

"Human activities have greatly altered global carbon, nitrogen, and phosphorus cycles, and nitrogen inputs are considered now 'high risk' and above a safe planetary boundary," said Lapointe. "Based on scientific research, population growth and land-use changes have increased nitrogen pollution and degradation of estuaries and coastal waters since at least the 1950s. Despite decreases in nitrogen loading in some coastal watersheds, N:P ratios remain elevated in many rivers compared to historic values. The trend toward higher N:P ratios in the major rivers in the Atlantic basin parallel the increased N:P ratios we now see in Sargasum."

Reference: "Nutrient content and stoichiometry of pelagic Sargassum reflects increasing nitrogen availability in the Atlantic Basin" by B. E. Lapointe, R. A. Brewton, L. W. Herren, M. Wang, C. Hu, D. J. McGillicuddy Jr., S. Lindell, F. J. Hernandez and P. L. Morton, 24 May 2021, Nature Communications.
DOI: 10.1038/s41467-021-23135-7

Study co-authors are Rachel Brewton, a research coordinator, and Laura Herren, a research biologist, both at FAU Harbor Branch; Chuanmin Hu, Ph.D., a professor of optical oceanography, University of South Florida; Mengqui Wang, Ph.D., a post-doctoral researcher in the College of Marine Science, University of South Florida; Dennis McGillicuddy, Jr., Ph.D., senior scientist and department chair of applied ocean physics and engineering, Woods Hole Oceanographic Institution; Scott Lindell, a research specialist, Woods Hole Oceanographic Institution; Frank J. Hernandez, Ph.D., an assistant professor, Division of Coastal Sciences, University of Southern Mississippi; and Peter Morton, Ph.D., Department of Earth, Ocean and Atmospheric Science, Florida State University.

This research was funded by the U.S. NASA Ocean Biology and Biogeochemistry Program (NNX14AL98G, NNX16AR74G) and Ecological Forecast Program (NNX17AE57G), NOAA RESTORE Science Program (NA17NOS4510099), National Science Foundation (NSF-OCE 85-701 15492 and OCE 88-12055) and a Red Wright Fellowship from the Bermuda Biological Station.

# data[].attributes.attachment_link.title
Toxic "Dead Zone" - Surge in Nitrogen Has Turned Sargassum Into the World's Largest Harmful Algal Bloom

# data[].attributes.attachment_link.description
FAU Harbor Branch unique historical baseline (1983-2019) reveals dramatic changes in composition of sargassum. For centuries, pelagic Sargassum, floating brown seaweed, have grown in low nutrient waters of the North Atlantic Ocean, supported by natural nutrient sources like excretions from fishes

# data[].attributes.headline
How soil can help solve our climate problem

# data[].attributes.subject
How soil can help solve our climate problem

# data[].attributes.attachment_link.readable_text
In brief

"I want to set the state record for corn in Iowa, and I want to do it in a sustainable way," he says. That means harvesting more than 442 bushels per acre (27,742 kg per hectare), the record set in 2002 by Francis Childs.

Garrett, a self-described extreme farmer, sounds confident in his chances. He is the seventh generation in his family to grow corn and graze cattle in western Iowa. "Everything we do is important," he says. But when it comes to huge corn yields, there is one crucial element: carbon.

Garrett says his farming methods accomplish two laudable goals at once: they remove carbon dioxide from the atmosphere, and they use the carbon to build healthy soil. "Everyone needs to understand that carbon is energy to the soil," he says. "The more carbon you can put in the soil, the more your plants can become. We need to put carbon in our soil to improve our yields and to make the world a better place. We need to put as much carbon in the soil as we can to improve our bottom line."

The idea that farmers can capture carbon and improve their bottom lines at the same time is gaining ground in the agriculture community and among business leaders and policy makers. They would like to pay farmers for adopting practices, such as using cover crops and low-till methods, that take carbon from the atmosphere and store it, presumably for centuries, in the soil. Large-scale adoption of so-called carbon farming, proponents say, can transform the industry from a greenhouse gas emitter to a global carbon absorber.

One way farmers can get paid is to sell carbon credits for each metric ton of carbon dioxide equivalent they sequester. Private marketplaces for those credits are popping up now, and while their methodologies for verifying carbon practices and certifying credits appear robust, they are not all the same.

Credit: Ted Kornecki/USDA

The Biden-Harris administration has directed the US Department of Agriculture to help farmers adopt practices that sequester carbon. And in the Senate, the bipartisan Growing Climate Solutions Act would enable the USDA to standardize private carbon credit markets and certify third-party verifiers to boost farmers' confidence in the schemes. The European Commission is crafting similar farm supports and plans to launch a verified carbon market this year for the European Union.

But opinions vary in the farm and environmental communities about the best ways to help growers transition to climate-smart practices. Some experts say focusing just on carbon credits takes too narrow a view of soil health practices, while others fear the programs will benefit only large landowners. Meanwhile, scientists are still researching the mechanisms of soil carbon sequestration, including how much carbon can be stored, for how long, and how to measure it.

As one of the first farmers in the US to sell carbon credits, Garrett acknowledges that not everyone is on board. "There's a lot of skepticism out there," he says. "I do think there should be one standard practice for the science on how much we're sequestering."

How carbon programs work

For hundreds of years, farmers have cultivated lands that provided fertility, in the form of soil organic matter, to their crops. Much of that organic matter originated from the lands' original cover of forests or native grasslands. But over the generations, a large fraction of that organic matter washed or blew away.

These days, most agricultural soil is considered degraded. Crops still grow because farmers supply them with fertilizers and water and protect them with pesticides.

Carbon farming by the numbers

58.0%: Nitrous oxide

40.8%: Methane

1.2%: Carbon dioxide

It costs farmers a lot of money to raise crops and animals on degraded soil. But scientists say that soil is an opportunity wearing a dusty disguise. Farmers and ranchers can build back their soil by adding organic matter. Made up of decaying plants and the bodies of soil microbes, that organic matter can trap carbon for hundreds and even thousands of years.

Garrett was invited to be the first farmer to sell carbon credits on Nori's new carbon credit marketplace because he's the first to try a lot of new things. He's a member of a group of farmers around the US that test new agriculture products and post their results on the website xtremeag.farm.

"It is an honor, and I'm excited to be the first," Garrett says. So far, he's sold $150,000 of carbon credits; the first buyer was the e-commerce firm Shopify. He expects to make $340,000 from his first year's participation when all are sold.

Garrett worked with Locus Agricultural Solutions to generate his credits and certify them. Locus sells soil microbes that consume organic matter, trap carbon, and make nutrients like nitrogen available to plants. The company has launched a credit-generating program called CarbonNOW.

In addition to using Locus's Rhizolizer Duo microbial product, Garrett planted cover crops that protect his fields from erosion and add organic matter. He skipped tilling his fields and added liquid compost. Garrett also brought in calves and cattle to graze on cover crops and crop residues.

Soil scientists have been advocating the same practices, sometimes called regenerative agriculture, for years because they support the biological mechanisms needed for healthy soil. "Everything that we talk to farmers about the principles of soil health management all build soil organic carbon and retain soil carbon," says Cristine Morgan, chief scientific officer for the nonprofit Soil Health Institute.

Now many companies in the agriculture supply chain are launching programs to reward farmers who transition to practices that pull measurable amounts of carbon from the atmosphere. Some programs generate their own funding by selling carbon credits to companies that want to offset greenhouse gas emissions from their operations.

Those suppliers include another purveyor of agricultural microbes, Indigo Agriculture, which is also working with growers to create and sell carbon credits via its Indigo Carbon program.

Technology firms that supply precision agriculture tools, including Farmers Business Network and Farmers Edge, are helping farmers gather and track data to qualify for carbon credits. The start-up PastureMap, which emerged from stealth in 2020, has a program for ranchers called Grassroots Carbon.

Big companies that sell seeds, pesticides, and fertilizers, including Bayer, Nutrien, and Yara, are recruiting farmers for their own programs. Food companies like Cargill, General Mills, and the dairy cooperative Land O'Lakes also have programs that help growers shift to regenerative techniques that put carbon in soil.

At a minimum, a soil carbon program asks farmers to start one or two soil health practices-usually cover crops and low- or no-till farming-and pays them a set amount per land unit or per estimated ton of carbon stored.

The most sophisticated programs aim to scientifically account for all greenhouse gases absorbed and emitted by farms. They generate third-party-verified carbon credits that corporate purchasers can use to fulfill net-zero carbon pledges. Currently, buyers are paying about $20 per metric ton of carbon dioxide equivalent, of which $15 goes to the farmer.

In addition to Shopify, firms including IBM, JPMorgan Chase, Marathon Oil, Microsoft, and New Belgium Brewing have bought some of the first certified carbon credits in the US.

Carbon farming is shaping up to be good business for agriculture companies offering climate change mitigation products and services, Laurence Alexander, a stock analyst for Jefferies Financial Group, tells investors in a recent research report. It can drive sales for companies that sell seeds and chemicals, including herbicides and fungicides, because conventional farmers use more of them to control an uptick in weeds and diseases during the transition to no-till operations.

Verifying carbon credits

For the agricultural carbon market to gain ground, the science supporting the greenhouse gas impacts must be credible. Companies learned a lesson from the Chicago Climate Exchange, says Jonathan Hennek, global head of product for carbon at Indigo. The marketplace operated from 2003 to 2010 and set its own standards for what constituted a credit.

"They were playing in their own sandbox. When people lost confidence in the quality of the standards, the market collapsed," Hennek says.

More recently, some forest carbon credits and systems, including credits sold by the conservation group the Nature Conservancy and a program administered by the California Air Resources Board, have been criticized by environmental watchdogs as not representing actual new carbon storage.

To avoid those outcomes, Indigo worked with the third-party climate standards organizations Verra and Climate Action Reserve as well as nongovernmental organizations, scientists, and growers to develop methodologies to prove that the practices the firm promotes improve farms' greenhouse gas footprints.

Verra and Climate Action Reserve maintain an inventory of practices that have been scientifically shown to boost the ability of crops or pastures to transfer carbon from the atmosphere into the soil or to reduce the amount of nitrous oxide and methane that a farm emits. Farmers can choose the practices they'd like to start using as well as the amount and location of fields where that change will happen.

To generate credits, a program has to show that new practices, when implemented in the field, measurably affected greenhouse gases. For example, showing that cover crops and reduced tillage added carbon to the soil requires many soil samples to obtain benchmark data and measure the change in soil carbon each year.

Farmers' records of past practices provide evidence that the new farming practice-say, using cover crops-and not, for example, great weather, is responsible for the increased soil carbon. This concept, known as additionality, is core to the value of carbon credits. Additionality also means something more nuanced: that the farmer would not have adopted this practice if not for the carbon credit payment.

Verra's methodology for quantifying soil carbon runs 33 detailed pages. It governs how to assess a landscape, including its soil types, soil layers, and vegetation species. It instructs soil testers on how to create a soil-sampling plan: how many samples to take, where to take them, at what depths, and when. It says how to account for carbon content using soil mass, soil density, and soil volume, as well as how to measure changes in those variables over the growing season.

Not surprisingly, a major role for Indigo and Locus in helping farmers generate carbon credits has been to pay for the required third-party soil testing. The companies keep a portion of the credit sale to cover testing costs.

Hennek, who has a background in chemistry, says Indigo's approach captures the trade-offs that can happen when farmers embark on something new. "We don't only look at what a cover crop adds to soil carbon," he explains. "What happens if a farmer decides to put a synthetic nitrogen on that cover crop? It's essential to measure all of the potential emissions factors," such as additional nitrogen oxide.

Industry takes the lead

Locus and Indigo say the pieces are in place for farmers to begin profiting from carbon credits, assuming they can meet the high bar for verification. And now is a good time because demand from buyers is strong.

"We believe the carbon credit that is the highest quality will get the highest price, and we expect the prices to rise. That money flows directly to the farmers, which creates a virtuous cycle because it enables them to add more practices," Hennek says.

But to expand beyond pioneers like Garrett and attract large numbers of farmers, firms scaling climate-friendly growing practices will need simple, straightforward techniques.

One way to speed adoption is to make it easier for farmers to gather the data they need to earn certified carbon credits. Jeff Seale, director of climate policy and strategy at Bayer Crop Science, says there isn't enough money in climate credits to fund an army of soil sample takers and document wranglers.

Bayer's scientists have launched pilot programs in which farmers use the digital tools of its popular Climate FieldView platform to automate record keeping and gather the data needed to prove that they are sequestering carbon.

Farmers already use FieldView to map, plan, and manage their fields, inputs, and crops and measure their harvests in detail. Bayer's program pays corn and soybean farmers in nine states in the US Midwest $10 per acre ($24.70 per hectare) when they adopt cover crops or reduce tillage. A pilot program in Brazil helps farmers use FieldView data to comply with government requirements for preserving a portion of farmland as native forest.

Growers share their FieldView data with Bayer, which will use it along with other data to build proprietary carbon models. "What we're trying to do is have this integrated platform that drives the simplicity for the system," Seale says.

In the US, FieldView includes 80 years of USDA data on soil types, historical yields, and weather to estimate greenhouse gas emissions. On top of that, Bayer is building models of crop rotations and agronomic practices.

Other companies are working on technologies they say will provide data that can be combined with machine learning and artificial intelligence to model soil carbon. A number of agricultural technology firms, Indigo included, say they can use high-resolution satellite images to track and verify the use of cover crops and crop rotation. Scientists and start-ups are developing remote sensing technology to measure the carbon content in the top 15 cm of soils. Future advances will enable carbon detection deeper in the soil.

Another company, LaserAg, won an Indigo contest for its soil-sampling and lab-testing technology. The system analyzes GPS-tagged field samples with laser-induced breakdown spectroscopy to measure the organic content in soil and its density, texture, total nitrogen, and pH in less than 1 min.

The Soil Health Institute is working with the start-up Yard Stick on an in-field soil carbon sensor for researchers and ag consultants. The long probe measures carbon concentration at different soil depths with the help of data from US soil spectroscopy libraries.

Ryan Sirolli, global row crop sustainability director at Cargill, cautions against taking too narrow a view of soil health by linking it solely to captured carbon.

Practices that build soil organic matter do more than just trap carbon, Sirolli says. They raise soil's water-holding capacity, make crops more resilient to weather stress, capture nitrogen, improve water quality, and increase biodiversity. "If you get stuck just working within the carbon market and get caught up in its limitations, you might miss all of these benefits that you can really lean into," Sirolli says.

As a buyer of grain, Cargill is familiar with the economics of farming and the demands of food companies and consumers. It has committed to working with farmers to transition 10 million acres (4 million hectares) of North American farmland to regenerative systems by 2030.

Cargill worked with soil scientists and economists at the Soil Health Institute to quantify the financial upsides of soil health practices by collecting data on 100 farms in nine states. Farmers reported spending more money on seeds-likely for those cover crops-but less on fertilizers and soil amendments, pesticides, fuel, labor, and equipment. They also earned more revenue, thanks to higher yields.

In total, the researchers found that 85% of farmers growing corn increased their net farm income by an average of $52 per acre ($128 per hectare), while 88% of soybean growers saw an average increase of $45 ($111 per hectare). Nearly all the farmers reported improvements in their crops' resilience to extreme weather.

But the farmers in the study have planted cover crops or followed no- or low-till methods for a decade or more, meaning they don't qualify for a program like Indigo's. So Cargill is piloting programs to help farmers more quickly qualify for carbon credits, water credits, and biodiversity credits. One example is Cargill's Soil and Water Outcomes Fund, which is enrolling farmers in Illinois, Iowa, and Ohio.

Government wants a role

Just 1 week after his inauguration, President Joe Biden issued an executive order directing the USDA to seek input from farmers, conservation groups, and other stakeholders on developing a climate strategy, including voluntary programs for "additional, measurable, and verifiable carbon reductions and sequestration."

The exact strategy is still being developed. The USDA solicited comments from stakeholders from mid-March until April 29 and is now considering the options.

One way the government can help, according to comments from environmental and farm groups, is by setting standards that would build confidence in private carbon credit markets and encouraging farmers to participate. For example, the USDA could boost participation by funding existing public-private partnerships.

The US Congress is also considering legislation that would empower the USDA to widen participation in carbon markets. Sen. Debbie Stabenow (D-MI), chair of the Senate Committee on Agriculture, Nutrition, and Forestry, and Sen. Mike Braun (R-IN) introduced the Growing Climate Solutions Act (S. 1251), which would establish a USDA certification program to help standardize private carbon credit markets and boost farmers' confidence in the schemes. The USDA would certify third-party verifiers and technical assistance providers. It would also develop a website to serve as a one-stop shop of information for farmers who want to participate in private carbon markets.

Those ideas have caught on in the European Union as well, as part of the EU's Farm to Fork Strategy. The European Commission is promoting carbon farming to member states and will help fund incentives. It plans to launch a carbon market by the end of the year.

The Food and Agriculture Climate Alliance, a coalition of organizations representing US farmers, the food industry, state governments, and environmental groups, endorses the Growing Climate Solutions Act, pointing out that it "establishes a robust USDA advisory council composed of farmers, scientists and other climate stakeholders."

Meanwhile, USDA secretary Tom Vilsack is leveraging existing USDA programs, particularly the Conservation Reserve Program (CRP), which pays farmers to keep land out of agricultural production. The current CRP is estimated to mitigate more than 12 million metric tons of carbon dioxide equivalent annually. The USDA hopes to expand the program by up to 4 million acres (1.6 million hectares), which it says would mitigate an additional 3 million metric tons of CO ₂ equivalent.

In April, Vilsack also announced increased funding for public-private partnerships that promote climate-smart agriculture, including $330 million for 85 Regional Conservation Partnership Program projects and $25 million for On-Farm Conservation Innovation Trials.

Finally, the USDA is considering creating a carbon bank with money from a $30 billion fund called the Commodity Credit Corporation. It would provide incentives for farmers to access carbon markets. But many Republican lawmakers are pushing back on that idea, claiming that Congress would need to approve any funding for climate purposes before the USDA could use it.

Some sustainable farming experts and business organizations warn that carbon bank and carbon credit programs may be limited in their effectiveness and unjust in distributing rewards.

In comments submitted to the USDA, the American Sustainable Business Council, a coalition of firms focused on sustainability and social responsibility, said carbon farming "should not be promoted as an alternative to adequate regulation of polluters, especially in environmental justice communities." The group also worries that carbon markets will benefit larger-scale producers at the expense of small-scale farmers.

Cargill's Sirolli adds that financial incentive programs will have limited impact if they don't address how benefits will be distributed when farmers grow crops on land that they don't own. "It's probably one of the biggest single hurdles to overcome," he says. "Nearly half of the acreage farmed in the US is on rented or leased land."

Another concern is that farms with very degraded soil could see large improvements and get outsize payments, says Yichao Rui, a soil scientist and the director of the Farming Systems Trial at Rodale Institute, an organic and regenerative farming research and education organization.

"I personally think that we should reward farmers by the practice and not their soil carbon measurement," Rui says. "There are also a lot of farmers doing great things already, and they need to maintain their carbon content. If they are left out of the system, that is not fair."

More to learn about soil carbon

Experts agree that scaling up carbon credit markets will require reliable models. But building models that link on-farm practices to sequestered carbon is challenging because soil carbon cycles are complex, and soils vary widely.

"Soil carbon depends on a lot of factors-temperature of region, climate factors, mineralogy, and vegetation that coevolved with these factors," Rui says.

Rui says lands managed for agriculture have lost 25-75% of their carbon-containing topsoil over the years. In Pennsylvania, where Rodale conducts its field studies, soil organic carbon has fallen to roughly 2% of soil mass from 4% before the start of widespread farming, he says.

Globally, that adds up to a lot of room to store carbon. In a 2020 white paper, Rui and coauthors say cover cropping alone could sequester roughly 4% of annual CO ₂ emissions. If many regenerative methods are stacked together, the sequestration potential rises to nearly a third of global CO ₂ emissions. And because so much land is used to graze livestock, regenerative pasture practices could store even more carbon.

Achieving that potential calls for more science backing soil carbon models, says Francesca Cotrufo, a professor of soil and crop science at Colorado State University. She is a member of Colorado State's Soil Carbon Solutions Center, a team of soil scientists, modelers, chemists, social scientists, and economists. Her research focuses on understanding and quantifying how carbon and nitrogen cycle in and out of soil.

To track how carbon ends up in soil, how much stays there, and for how long, Cotrufo measures old carbon put into the soil by past forests and compares it with newer carbon from corn crops using their different ratios of ¹³C to ¹⁴ C. She also uses isotope labeling to trace carbon and nitrogen flows from plants to soil and microbes.

Cotrufo eschews soil analysis methods like combustion and chemical separation that measure total carbon. Instead, she separately examines the lighter, coarser soil fractions containing decomposing plant matter, called particulate organic matter, and the heavier, finer fractions of carbon stuck to inorganic matter from weathered rock, called mineral-associated organic matter.

"It's a better approach to identify fractions because they form differently, persist in soil via different mechanisms, and are differently sensitive to management, climate change, and disturbance," Cotrufo says.

The particulate organic matter primarily occupies the top 30 cm of soil, where microbes consume sugars exuded from plant roots and break down plant and animal matter, making nitrogen and other nutrients available to plants. That's how compost and other organic matter help boost crop productivity. But microbial respiration also sends a portion of that carbon back to the air as CO ₂.

When those microbes die, the carbon in their cell walls, along with other carbon that has escaped microbial digestion, moves deeper into the soil, where it forms long-term associations with clay particles and calcium, iron, and aluminum oxides. The resulting mineral-associated organic matter is less accessible to microbes and plants; it can stay in soil as long as 1,000 years.

"Soil biology is the key to get the system going and maintain the system. But in conventional ag, the role of microbes has been ignored," Rui says. Adding beneficial microbes to the soil may help jump-start the revival of depleted soil, Cotrufo adds, but success depends on continually feeding them organic matter and may require yearly applications of microbial products.

Both particulate and mineral-associated organic matter are valuable to farmers. Cotrufo and Rui describe them as money in the bank. High-quality organic matter from crop residues, cover crops, or compost first fills a checking account to pay this season's bills. Over time, if the soil is not disturbed by plowing, a postharvest surplus builds up, forming mineral-associated organic matter-a farm's version of long-term savings.

In Iowa, Garrett didn't use a computer model to predict how much more carbon and nitrogen he'd get from soil health practices and the microbial product-he just tried them and measured the results. He measured the nitrogen level in his corn plants and was excited to see it had jumped 12%.

What's more, he says that during a stretch of July, when his corn hit its rapid growth phase, his soil's pH dropped 2 points, meaning that the hungry plants were producing huge quantities of acidic, carbon-laden sugars that they pushed into the soil through their roots.

"I thought, 'Holy cow, we're watching photosynthesis and carbon sequestration in real time,' " he says.

Last season, Garrett's hopes for his corn crop were flattened by the Midwest derecho. This year, he's going to try again to beat the state yield record. "For a farmer, it would be like breaking Roger Maris's home run record," he says. "If I can do that and show the environmental folks we can do it positively and sustainably, that's a big message."

Sign up for C&EN's must-read weekly newsletter

# data[].attributes.attachment_link.title
How soil can help solve our climate problem

# data[].attributes.attachment_link.description
In brief "I want to set the state record for corn in Iowa, and I want to do it in a sustainable way," he says. That means harvesting more than 442 bushels per acre (27,742 kg per hectare), the record set in 2002 by Francis Childs.

# data[].attributes.attachment_link.title
Aquaculture research park redefining what it means to be a fish farm

# data[].attributes.attachment_link.description
"Wild caught" has become a desired attribute at the fish counter. But that may be changing. "CBS This Morning: Saturday" co-host Jeff Glor spoke to experts on why fish farming may be repairing a bad reputation to become a key player in the world's food supply.

# data[].attributes.headline
Noise pollution reduces the reproductive success of the house sparrow

# data[].attributes.subject
Noise pollution reduces the reproductive success of the house sparrow

# data[].attributes.attachment_link.readable_text
Credit: Pixabay/CC0 Public Domain

The study presents a new line of research, since so far there have been very few studies that have focused on loud and intermittent noises of a recreational nature, as is the case of traditional festivals, and the effects they cause on urban fauna.

The Cavanilles Institute of Biodiversity and Evolutionary Biology of the University of Valencia, in collaboration with the University of Alicante, has studied how noise pollution from the Moors and Christians festivities affects the reproduction of the house sparrow. The study presents a new line of research, since so far there have been very few studies that have focused on loud and intermittent noises of a recreational nature, as is the case of traditional festivals, and the effects they cause on urban fauna.

The authors of the article, Edgar Bernat and José Antonio Gil, from the Cavanilles Institute, and Germán López, a researcher at the University of Alicante, have found that the population of juvenile sparrows decreases in those towns that celebrate the Moors and Christians festival during the breeding season. This is due to the noise pollution caused by the firecrackers, musket shots and fireworks from the festivity.

"Recreational and intermittent noise has been studied very little in terms of the effects it has on urban fauna. In this case, we studied the house sparrow, since it is an urban bioindicator and we wanted to know to what extent the festivals that coincided with the breeding season had an influence on their reproduction, which is another aspect that had not been analyzed until now in any species," explains Edgar Bernat.

To achieve this, the study, published in the journal Environmental Pollution, analyzed five pairs of towns depending on whether they have the holidays between April and May and therefore coincide with the breeding season; or if they are held outside the spring. According to Bernat, "we not only wanted to make the comparison based on when the festivities are, but also that they were more or less similar municipalities and that they are relatively close." Thus, Banyeres de Mariola was compared to Bocairent, Onil to Castalla, Muro de Alcoi to Cocentaina, Petrer to Villena and Alcoi to Ibi.

To carry out the sampling, the researchers have counted the juvenile individuals-born in the year of study-that were in an area of one hundred meters around the Moors and Christians route fifteen and thirty days after the end of the festivities. Thus, they have been able to obtain the ratio of juvenile and adult individuals that has served as an indicator of youth productivity.

This analysis, which was carried out in 2019, showed that there were more juvenile sparrows in localities where the festivals are outside the breeding season. "When we were going to publish these results, the pandemic arrived, everything was canceled and we saw an opportunity to make a comparison in those municipalities where the breeding season did coincide with the Moors and Christians," says the expert.

Thus, the article points out that the youth ratios in 2020 were in both types of localities, with parties in spring, canceled, and with parties at another time. Likewise, the authors have seen that the confinement has not had a notable effect on the normal reproductive success of the species, although it did improve in the localities where the spring festivals were canceled.

Bernat believes that this is due to the fact that the sparrow's reproduction not only depends on acoustic factors, but also others such as the food that people provide and that disappeared in the confinement. Therefore, this study also leaves possible future lines of research regarding other elements that affect the reproduction of fauna. In addition, another of the possible avenues for further study is to know how air pollution created by the parties themselves, and not just noise pollution, affects sparrows.

As the researcher mentions, "we do not say that traditional festivals should be canceled or that they be transformed because it affects the reproduction of the sparrow. However, we believe that compensatory measures must be carried out to help them in another way, because one of the decisions that harms birds the most is the absence of green policies in cities. For example, placing natural grass instead of artificial grass, avoid paving parks and adapting house tiles so that they can nest. In other words, provide them with facilities despite the fact that you harm them during those festivities."

More information: Edgar Bernat-Ponce et al. Recreational noise pollution of traditional festivals reduces the juvenile productivity of an avian urban bioindicator, Environmental Pollution (2021). DOI: 10.1016/j.envpol.2021.117247

# data[].attributes.attachment_link.title
Noise pollution reduces the reproductive success of the house sparrow

# data[].attributes.attachment_link.description
The study presents a new line of research, since so far there have been very few studies that have focused on loud and intermittent noises of a recreational nature, as is the case of traditional festivals, and the effects they cause on urban fauna.

# data[].attributes.headline
Models show corals more resistant to ocean warming if they swap for more heat-resistant varieties of algae

# data[].attributes.subject
Models show corals more resistant to ocean warming if they swap for more heat-resistant varieties of algae

# data[].attributes.attachment_link.readable_text
Credit: Pixabay/CC0 Public Domain

A team of researchers from the University of California, the NOAA/OAR Geophysical Fluid Dynamics Laboratory and the University of British Columbia has found via simulations that corals that replace poorly performing algae with more heat resistant varieties are more resistant to coral bleaching as oceans warm due to global warming. In their paper published in the journal Nature Climate Change, the group describes the factors that went into the development of their simulations and what they showed over time.

Prior research has shown that under climate change, the oceans absorb some of the heat, resulting in ocean warming. Prior research has also shown that carbon dioxide released into the atmosphere is also causing more acidic oceans. Additionally, global warming is known to cause bleaching of coral reefs. As a response to warmer water temperatures, corals expel the algae that live in their tissues, leaving the corals to die. The algae remove waste products from healthy corals and also supply them with oxygen. Without these services, the coral cannot survive. In this new effort, the researchers noted that some algae are more heat tolerant than others and that corals respond to them by allowing them to remain in their tissue. They created a model to simulate how corals might respond as the oceans warm if they were able to swap out poorly performing algae with strains that were more tolerant of heat.

Their model incorporates data from 1,925 coral reefs from around the globe, along with data regarding strains of algae. They then ran their simulation under four possible scenarios involving different rises in ocean temperatures due to different amounts of greenhouse gas emissions into the atmosphere in the coming years.

The simulations demonstrate that under moderate global warming conditions, many of the coral reefs around the world could survive if they were able to swap out for more heat-resistant algae. Their simulation also showed a limited impact on coral bleaching due to increasing acidification of the worlds' oceans.

More information: Cheryl A. Logan et al. Quantifying global potential for coral evolutionary response to climate change, Nature Climate Change (2021). DOI: 10.1038/s41558-021-01037-2

© 2021 Science X Network

# data[].attributes.attachment_link.title
Models show corals more resistant to ocean warming if they swap for more heat-resistant varieties of algae

# data[].attributes.attachment_link.description
A team of researchers from the University of California, the NOAA/OAR Geophysical Fluid Dynamics Laboratory and the University of British Columbia has found via simulations that corals that replace poorly performing algae with more heat resistant varieties are more resistant to coral bleaching as oceans warm due to global warming.

# data[].attributes.headline
Watching a coral reef die in a warming ocean

# data[].attributes.subject
Watching a coral reef die in a warming ocean

# data[].attributes.attachment_link.readable_text
The Chagos Archipelago is one of the most remote, seemingly idyllic places on Earth. Coconut-covered sandy beaches with incredible bird life rim tropical islands in the Indian Ocean, hundreds of miles from any continent. Just below the waves, coral reefs stretch for miles along an underwater mountain chain.

It's a paradise. At least it was before the heat wave.

When I first explored the Chagos Archipelago 15 years ago, the underwater view was incredible. Schools of brilliantly colored fish in blues, yellows and oranges darted among the corals of a vast, healthy reef system. Sharks and other large predators swam overhead. Because the archipelago is so remote and sits in one of the largest marine protected areas on the planet, it has been sheltered from industrial fishing fleets and other activities that can harm the coastal environment.

But it can't be protected from climate change.

In 2015, a marine heat wave struck, harming coral reefs worldwide. I'm a marine biologist at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, and I was with a team of researchers on a 10-year global expedition to map the world's reefs, led by the Khaled bin Sultan Living Oceans Foundation. We were wrapping up our work in the Chagos Archipelago at the time. Our report on the state of the reefs there was just published in spring 2021.

As the water temperature rose, the corals began to bleach. To the untrained eye, the scene would have looked fantastic. When the water heats up, corals become stressed and they expel the tiny algae called dinoflagellates that live in their tissue. Bleaching isn't as simple as going from a living coral to a bleached white one, though. After they expel the algae, the corals turn fluorescent pinks and blues and yellows as they produce chemicals to protect themselves from the Sun's harmful rays. The entire reef was turning psychedelic colors.

That explosion of color is rare, and it doesn't last long. Over the following week, we watched the corals turn white and start to die. It wasn't just small pieces of the reef that were bleaching - it was happening across hundreds of square miles.

What most people think of as a coral is actually many tiny colonial polyps that build calcium carbonate skeletons. With their algae gone, the coral polyps could still feed by plucking morsels out of the water, but their metabolism slows without the algae, which provide more nutrients through photosynthesis. They were left desperately weakened and more vulnerable to diseases. We could see diseases taking hold, and that's what finished them off.

We were witnessing the death of a reef.

Rising temperatures increase the heat wave risk

The devastation of the Chagos Reef wasn't happening in isolation.

Over the past century, sea surface temperatures have risen by an average of about 0.13 degrees Celsius (0.23 F) per decade as the oceans absorb the vast majority of greenhouse gas emissions from human activities, largely from the burning of fossil fuels. The temperature increase and changing ocean chemistry affects sea life of all kinds, from deteriorating the shells of oysters and tiny pteropods, an essential part of the food chain, to causing fish populations to migrate to cooler water.

Corals can become stressed when temperatures around them rise just 1 C (1.8 F) above their tolerance level. With water temperature elevated from global warming, even a minor heat wave can become devastating.

In 2015, the ocean heat from a strong El Niño event triggered the mass bleaching in the Chagos reefs and around the world. It was the third global bleaching on record, following events in 1998 and 2010.

Bleaching doesn't just affect the corals - entire reef systems and the fish that feed, spawn and live among the coral branches suffer. One study of reefs around Papua New Guinea in the southwest Pacific found that about 75% of the reef fish species declined after the 1998 bleaching, and many of those species declined by more than half.

Research shows marine heat waves are now about 20 times more likely than they were just four decades ago, and they tend to be hotter and last longer. We're at the point now that some places in the world are anticipating coral bleaching every couple of years.

That increasing frequency of heat waves is a death knell for reefs. They don't have time to recover before they get hit again.

Where we saw signs of hope

During the Global Reef Expedition, we visited over 1,000 reefs around the world. Our mission was to conduct standardized surveys to assess the state of the reefs and map the reefs in detail so scientists could document and hopefully respond to changes in the future. With that knowledge, countries can plan more effectively to protect the reefs, important national resources, providing hundreds of billions of dollars a year in economic value while also protecting coastlines from waves and storms.

We saw damage almost everywhere, from the Bahamas to the Great Barrier Reef.

Some reefs are able to survive heat waves better than others. Cooler, stronger currents, and even storms and cloudier areas can help prevent heat building up. But the global trend is not promising. The world has already lost 30% to 50% of its reefs in the last 40 years, and scientists have warned that most of the remaining reefs could be gone within decades.

While we see some evidence that certain marine species are moving to cooler waters as the planet warms, a reef takes thousands of years to establish and grow, and it is limited by geography.

In the areas where we saw glimmers of hope, it was mostly due to good management. When a region can control other harmful human factors - such as overfishing, extensive coastal development, pollution and runoff - the reefs are healthier and better able to handle the global pressures from climate change.

Establishing large marine protected areas is one of the most effective ways I've seen to protect coral reefs because it limits those other harms.

The Chagos marine protected area covers 640,000 square kilometers (250,000 square miles) with only one island currently inhabited - Diego Garcia, which houses a U.S. military base. The British government, which created the marine protected area in 2010, has been under pressure to turn over control of the region to the country of Mauritius, where former Chagos residents now live and which won a challenge over it in the International Court of Justice in 2020. Whatever happens with jurisdiction, the region would benefit from maintaining a high level of protection.

A warning for other ecosystems

The Chagos reefs could potentially recover - if they are spared from more heat waves. Even a 10% recovery would make the reefs stronger for when the next bleaching occurs. But recovery of a reef is measured in decades, not years.

So far, research missions that have returned to the Chagos reefs have found only meager recovery, if any at all.

We knew the reefs weren't doing well under the insidious march of climate change in 2011, when the global reef expedition started. But it's nothing like the intensity of worry we have now in 2021.

Coral reefs are the canary in the coal mine. Humans have collapsed other ecosystems before through overfishing, overhunting and development, but this is the first unequivocally tied to climate change. It's a harbinger of what can happen to other ecosystems as they reach their survival thresholds.
This article is republished from The Conversation under a Creative Commons license. Read the original article.

# data[].attributes.attachment_link.title
Watching a coral reef die in a warming ocean

# data[].attributes.attachment_link.description
The Chagos Archipelago is one of the most remote, seemingly idyllic places on Earth. Coconut-covered sandy beaches with incredible bird life rim tropical islands in the Indian Ocean, hundreds of miles from any continent. Just below the waves, coral reefs stretch for miles along an underwater mountain chain. It's a paradise.

# data[].attributes.headline
Enlist the Ocean in Combatting Climate Change

# data[].attributes.subject
Enlist the Ocean in Combatting Climate Change

# data[].attributes.attachment_link.readable_text
Climate scientists and marine advocates are calling on governments worldwide to look beyond green policymaking when it comes to climate change. They say a critical shade is missing in the fight against global warming.

Blue.

Countries must recognize the important role that oceans have in limiting climate change and enact policies to protect marine ecosystems, the U.K.-based Environmental Justice Foundation said yesterday in a report endorsed by environmental experts and advocates.

More than half of the world's biological carbon is captured by animals and plants living in or around the oceans, but this so-called blue carbon and its associated ecosystems are mostly neglected in climate policy, says a letter accompanying the report.

The report highlights studies showing that mangrove forests store up to four times more carbon per hectare than tropical rainforests. Seagrass meadows store nearly 20 gigatonnes of carbon worldwide. According to Conservation International, up to 10 times more carbon is stored in coastal habitats than in tropical forests.

That means the oceans could soak up large quantities of atmospheric carbon if their ecosystems are restored and protected, the report says. Up to 200 million metric tons of CO2 could be captured annually by blue carbon sinks like mangroves, seagrasses, salt marshes and kelp forests, according to the report.

"Our coastal ecosystems are champions at removing carbon dioxide from the atmosphere and storing it in soils," said Patrick Megonigal, who studies how coastal marshes and forests respond to climate change at George Mason University and is a signatory of the letter.

Even marine wildlife like great whales capture and store carbon in their bodies over their lifetimes.

Yet those ecosystems and the creatures they support are threatened by rising water temperatures, acidification, overfishing and commercial shipping, the report says.

Seagrass is estimated to release nearly 300 million tons of carbon each year based on rates of lost ecosystems. That figure is higher for coastal wetlands and mangroves, which account for up to 10% of all greenhouse gas emissions from deforestation, despite comprising less than 1% of tropical forest area, according to a study in Nature Geoscience.

"Unfettered human activities are turning these incredible carbon sinks into sources of greenhouse gas emissions," Isabella Shraiman, a climate campaigner and lead author of the Environmental Justice Foundation report, said in an email.

They don't need to be, she argues.

"Blue carbon solutions can be a low-hanging fruit within an ambitious climate mitigation policy portfolio and address the triple emergency of the climate crisis, biodiversity collapse, and human rights," she said.

The letter urges leaders to set targets for protecting and restoring marine ecosystems as part of their commitments under the Paris Agreement. It also calls for a moratorium on deep-sea mining, and for expanding marine-protected areas to cover at least 30% of the world's oceans and seas by 2030. Currently, less than 8% of ocean area is protected.

Marine-protected areas also lack the resources and enforcement authority for effective conservation. The same goes for national and international conventions governing ocean management and protection, the report states.

The report and letter point to a blueprint for ocean protection aimed at meeting the 30% target.

Many of those measures can help reduce carbon emissions and protect communities from the impacts of climate change. Blue-carbon ecosystems, for example, can help protect coasts from rising seas and severe storms, or provide habitats for fisheries while also acting as carbon sinks, experts say.

"The ocean has not played prominently until very recently in the climate mitigation space," Jane Lubchenco, a marine ecologist and adviser to the Biden administration's Office of Science and Technology Policy, said ahead of the White House climate summit in April. "Now the science is really leading the way and telling us that there is a phenomenal opportunity for the ocean to provide additional ways for us to mitigate climate that simply weren't on our radar screen before."

Organizers of yesterday's report make the case that marine protection is not a substitute for aggressive decarbonization.

"There has been a tendency for policymakers to silo environmental action: conservation policy is formulated separately from decarbonization policy, to the detriment of both," said Shraiman, the lead author. "What we need now is ambitious, holistic and joined up action."
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides essential news for energy and environment professionals.

# data[].attributes.attachment_link.title
Enlist the Ocean in Combatting Climate Change, Experts and Advocates Argue

# data[].attributes.attachment_link.description
Climate scientists and marine advocates are calling on governments worldwide to look beyond green policymaking when it comes to climate change. They say a critical shade is missing in the fight against global warming. Blue.

# data[].attributes.headline
Entire Buildings Can Be Wrapped in Jackets to Save Energy

# data[].attributes.subject
Entire Buildings Can Be Wrapped in Jackets to Save Energy

# data[].attributes.attachment_link.readable_text
On a normally peaceful residential road outside The Hague, the Dutch city that serves as seat of government, the whine of a hoisting crane and welding tools heralds a not-so-quiet housing revolution. Four workers standing above me on a scissor lift next to an apartment complex guide a thermally insulated facade 40 feet wide and one story tall into place against the existing wall. Its brickwork pattern of muted brown, grey and beige, and the triple glazed windows, perfectly fit the building's existing frame and openings.

The original windows and the very old brick walls had allowed cold drafts inside, and warm interior air to escape, wasting much of the energy used to heat the building. The new facade is primarily fire-resistant expanded polystyrene-essentially, hollow spheres that trap air to create a thick insulation layer-faced with hardened clay and sculpted into hundreds of very thin rectangles known as "brick slips."

This new building skin, prebuilt in a factory, was one of a dozen such facades to be attached to local buildings when I visited the suburb on a rainy day in early summer, each structure measured to millimeter precision. The installation is part of a concerted effort to transform energy-inefficient public housing into a set of ultralow-emission homes-without having to open a wall or remake an attic. The building was being wrapped in the equivalent of a winter jacket-or summer beer koozie-avoiding the need to insert insulation inside dozens of walls, lofts and attics. A similarly premade, lightweight, highly insulating material, complete with solar panels, would be installed on the roof, too.

In developed economies like the Netherlands and the United States, a big chunk of greenhouse gas emissions can be attributed to energy loss in residential buildings. But retrofitting homes to improve efficiency and reduce carbon footprint too often remains cumbersome and costly. The work requires a constellation of contractors and up-front financing that is off-putting for homeowners and landlords, despite the long-term environmental and financial benefits.

The Dutch government began to confront this climate challenge a decade ago by seed-funding a nonprofit program known as Energiesprong, or "energy leap" in Dutch. The initial investment helped bring together engineers, construction companies, hardware suppliers, financiers, regulators and landlords who figured out a way to mass-produce home retrofits.

Landlords planning a routine refurbishment of their housing stock can now simply add an energy retrofit to that process, with attractive new facades and roofs. An automated laser device takes precision measurements of a building's entire exterior in a matter of hours. The information is uploaded wirelessly to large factories where walls, windows, doors and solar roofs are mass-produced and fit together for the target building. Completed facades and roofs are trucked to the site and attached. Often, the building owner or residents see their annual energy costs fall to zero thanks to solar panels that sell excess power to the national grid, at least during the summer.

The average retrofit cost in the Netherlands is about $94,000 for a family home, typically a row house. That may sound high, but it is comparable to the cost of other routine renovations that deliver no energy savings. In one neighborhood in the city of Utrecht, more than a dozen houses and some 250 separate apartments retrofitted in 2019 saw their energy requirements fall from 225 kilowatt-hours per square meter to just 50 kilowatt-hours per square meter, on average. The remaining demand for energy was met with solar power.

These steep energy savings are prompting owners to sign up for retrofits without any public financing (although a solar subsidy is available). And other countries and communities are modeling new programs on the Energiesprong approach. Recently, the New York State Energy Research and Development Authority directed $30 million to its own program, called RetrofitNY.

The facades being installed in The Hague had been manufactured by RC Panels, a vendor two hours east of the city in Lemelerveld. The for-profit company is focused on insulating the country's more than two million row houses and many more apartment dwellings. Lianda Sjerps-Koomen, the firm's business development manager, walks me through a factory floor the size of an aircraft hangar, pointing out teams of workers pulling together the various layers of raw materials for a wall facade. Powerful vacuum cranes glom on to the panels, ushering them along an assembly line until a vast cutting machine slices out precisely measured window and door holes from the huge sheets of the expanded polystyrene and other layers.

"We need millions of houses to be renovated for the energy transition," Sjerps-Koomen says, as nearby camera-operated twin robot arms stamp six brick slips per second into one of the facades passing horizontally beneath them. The factory makes retrofits for hundreds of homes across the country each year, just as factories mass-produce cars or kitchen counters-an approach the housing retrofit industry is just not accustomed to, Sjerps-Koomen tells me.

At Factory Zero, another Dutch enterprise, engineers have designed a single rooftop module that houses an electric boiler for hot water, heat pump to warm the home, a smart meter and a solar power hookup. These units are often a major part of an energy retrofit, but are usually done piecemeal, by different contractors or trades, and typically require custom, costly installation. Just days after an order comes in to Factory Zero, the firm's installation teams can crane-drop a completed module onto the top of a flat- or pitched-roofed home, or next to one.

The company is making about 1,000 modules a year, and it charges around $16,000 per installation. It claims the typical cost in the Netherlands might be $35,000 if several different suppliers were working separately. As more homes are retrofitted, costs should come down. That change might allow many more large landlords, such as local governments, to finance the retrofit work as part of their regular property maintenance.

"We're trying to get the price of a modern energy system down to a level where it's affordable for everybody," says Jasper van den Munckhof, one of the company's co-founders. But he acknowledges that mass retrofitting will have to expand dramatically if government emissions targets for 2050 are to be met. The Netherlands needs "to do a thousand net-zero retrofits a day," he explains. "Currently, we're running at 10."

Mass production is crucial for this novel industry to expand, according to Donal Brown, a British academic who directs the Sustainable Design Collective and who co-authored a recent study of Energiesprong's applicability in the United Kingdom and other markets. He describes Energiesprong as a radical business model that requires retrofit innovations and support from policy makers. For example, Brown says Dutch power suppliers allowed electricity generated by panels to feed back into their grid system during the summer, in return for homeowner credit. Without that kind of "feed-in" or "net metering" tariff in place, in the winter those homes will have to pay for any energy use. Furthermore, he says, mass retrofits only become affordable if they are done on a large scale. Without rolling out thousands of modules at a time, costs cannot halve to the level he thinks is necessary-below around $50,000 per dwelling.

In the U.S., retrofitting progress is even slower. Although some states offer incentives or rebates to homeowners who make energy-based upgrades, this house-by-house approach, implemented with an array of different contractors and suppliers, is slow, and is not making much of a dent in residential emissions.

In New York state, the energy research authority used some of its $30 million investment in RetrofitNY to initiate a contest that selects specific affordable-housing properties for retrofits. Businesses were challenged to design, build and install an appropriate retrofit, with targets for tenant comfort, cost effectiveness, style and energy performance.

Authority CEO Doreen Harris says she wants to be a "catalyst" for the broader investments needed to retrofit the current housing sector, by demonstrating that mass-produced technologies and approaches work. Her team recently allocated $1.8 million to a $20 million retrofit project for nine buildings, containing 146 apartments, in the Bushwick neighborhood of Brooklyn. The nonprofit owner of the complex estimates the overhaul will reduce long-term energy use by 80 percent, and cut its annual costs by $180,000, once the final phase is completed later this year. If that project succeeds, polystyrene facades being hoisted onto the sides of large apartment buildings may become a more common sight.

# data[].attributes.attachment_link.title
Entire Buildings Can Be Wrapped in Jackets to Save Energy

# data[].attributes.attachment_link.description
On a normally peaceful residential road outside The Hague, the Dutch city that serves as seat of government, the whine of a hoisting crane and welding tools heralds a not-so-quiet housing revolution. Four workers standing above me on a scissor lift next to an apartment complex guide a thermally insulated facade 40 feet wide and one story tall into place against the existing wall.

# data[].attributes.headline
Pesticides Are Killing The Organisms That Keep Our Soils Healthy

# data[].attributes.subject
Pesticides Are Killing The Organisms That Keep Our Soils Healthy

# data[].attributes.attachment_link.title
Pesticides Are Killing the Organisms That Keep Our Soils Healthy

# data[].attributes.attachment_link.description
They harm worms, beetles and thousands of other subterranean species that are vital to agriculture

# data[].attributes.headline
Why Do Variants Such as Delta Become Dominant

# data[].attributes.subject
Why Do Variants Such as Delta Become Dominant

# data[].attributes.attachment_link.readable_text
If researchers were predicting which coronavirus variant would take over the world, the Delta variant would not have been their first guess. But since its first appearance in India in December 2020, the highly contagious variant has become the predominant strain of the virus, accounting for more than 90 percent of new COVID cases in the U.S.

Delta's emergence has caused a number of countries to reinstate travel and mask restrictions that had been loosened as vaccination rates rose. Although the vaccines appear mostly effective against Delta, the sheer number of cases increase the likelihood that it could cause "breakthrough infections" in vaccinated people. And it's still unclear whether it results in more severe disease than the previously circulating strains.

What is clear, however, is that Delta has a strong evolutionary advantage over earlier strains. "Its rate of increase is unlike any other in the history of this pandemic," says Vaughn Cooper, an evolutionary biologist at the University of Pittsburgh. Now, he and others are trying to figure out why this particular variant, which carries a suite of different mutations, has been so successful.

The virus's rapid spread may in part result from a fast replication rate. One recent study found that people infected with Delta had, on average, around 1,000 times more virus in their bodies-known as viral load-than those infected with the original strain, allowing them to infect more people quickly. The variant's advantage seems to stem from a combination of mutations in the spike protein: the part of the novel coronavirus that binds to ACE2 receptors on the surface of cells and allows the virus to infect them.

Scientists have also wondered whether Delta-in addition to its increased transmissibility-is able to escape the human immune system. It lacks a mutation called E484K, which helps a number of other variants partially avoid being neutralized by antibodies. But lab studies suggested that that a Delta mutation called L452R was even better at performing the same function.

In a recent preprint study, which has not yet been published in a journal, epidemiologist Nathan Grubaugh of Yale School of Public Health in New Haven, Conn., tested how 18 different variants reacted to serum taken from the plasma-the liquid component of blood-from 40 fully vaccinated health care workers. They found the participants' antibodies were able to neutralize the Alpha variants well, and Delta fairly well. But they were less effective against variants that carry the E484K mutations, such as Beta or Gamma, variants that were first identified in South Africa and Brazil, respectively.

The findings were surprising, given that Delta has been much more effective at spreading than Beta or Gamma. Even though the L452R mutation alone improved immune evasion, the actual Delta virus was not actually that good at it, suggesting that the specific combination of mutations on Delta gave the virus a unique function. "Even when we're trying to simplify things, it's hard to figure out which combinations become the next 'it' virus," Grubaugh says. He says that Delta's success suggests immune evasion might not give the virus as strong an evolutionary advantage as transmissibility, at least among unvaccinated people.

But that might not be true in every population. The Gamma variant, for instance, spread rapidly in Brazil but very little throughout the rest of the world. Some researchers suspect that COVID infection rates may have been higher in Brazil than in most countries, meaning that by the time Gamma appeared, the majority of people were already able to mount a strong immune reaction. In that population, evading the immune system would have been helpful for the virus.

Mehul Suthar, a virologist at Emory University in Atlanta, says there may be a limit to how many mutations a virus can acquire on the spike protein before it is no longer able to bind to the ACE2 receptor. "There's always going to be this tug-of-war between the virus gaining ability to transmit and spread and replicate, and its ability to escape antibody response," he says.

Suthar points out that the Kappa variant, which arose in India around the same time as Delta, shares most of Delta's mutations as well as a mutation similar to E484K. But Kappa has not spread worldwide, suggesting that these mutations may interact in some way that makes the virus less evolutionarily fit. "It was a bit of a surprise that it was the Delta variant that ended up taking off," Suthar says. "It was actually comforting."

Grubaugh thinks it is unlikely that significant new spike protein mutations are going to appear. Rather, the fittest virus will have a combination of the "best" mutations that let it spread widely among the most people. But it's hard to predict what those will be. "I think we have a pretty good handle on what mutations we should be looking out for, but that doesn't necessarily mean that if we see these, we know exactly how they'll perform," he says.

Cooper agrees. "It's logical that that combination [of high transmissibility and the ability to evade antibodies] will evolve if it can, provided infection numbers stay high," he says. The more people who remain unvaccinated, the greater the chance that something worse than Delta will arise.

Such a potential nightmare virus actually appeared last year: a variant called B.1.620 that was first seen in Africa. It carried the E484K mutation, along with a number of other spike protein mutations that might increase transmissibility. "With that alone you'd be going, 'Oh my god,'" says Emma Hodcroft, a genetics researcher at the University of Bern in Switzerland. But the number of B.1.260 cases soon declined. "It's clearly not quite as simple as you have all these mutations and you're the worst thing around," Hodcroft says.

The good news is that it would be relatively simple to tweak the mRNA vaccines made by Pfizer and Moderna to make them more effective against such a variant, says Nathaniel Landau, a microbiologist at New York University's Langone Medical Center. "If a variant did emerge that could escape better than the current one, you really would have a need for booster shots against that variant," he says.

In the meantime, however, the current vaccines remain the best way to prevent new variants from arising. "It's clear that with these viruses, it's not that if we defeat Delta we'll beat the pandemic," Suthar says. "There's just another that keeps emerging." If too few people get vaccinated and the virus spreads unchecked, he says, "there'll just be this endless cycle of infection, mutation and transmission."

# data[].attributes.attachment_link.title
Why Do Variants Such as Delta Become Dominant?

# data[].attributes.attachment_link.description
If researchers were predicting which coronavirus variant would take over the world, the Delta variant would not have been their first guess. But since its first appearance in India in December 2020, the highly contagious variant has become the predominant strain of the virus, accounting for more than 90 percent of new COVID cases in the U.S.

# data[].attributes.headline
North American Beaver Invasion Occupies Forests and Steppes in Southern Chile and Argentina

# data[].attributes.subject
North American Beaver Invasion Occupies Forests and Steppes in Southern Chile and Argentina

# data[].attributes.attachment_link.readable_text
In 1946 the Argentine Navy imported 10 beaver couples from Canada and set them free in Isla Grande, the deep south of Tierra del Fuego, with the intention of "enriching" the native fauna-and the local fur industry.

The consequences of such initiative were disastrous: Protected from hunting for 35 years, and devoid of natural predators, the beavers grew over 5,000 timestheir initial population, caused irreversible changes in the forest ecosystem, and started advancing over the continent. Now, a study published in Chilean Natural History suggests that the demographic explosion of those beavers could be bigger than suspected because it can take years or even decades for local inhabitants to notice the rodents' presence and their impact on the surrounding ecosystems. "There could be populations of beavers moving around in the continent and in the islands we don't know anything about," biologist Giorgia Graells, of the Institute of Patagonia at Magallanes University and lead author of the study, told Scientific American.

In order to accurately determine whether a beaver has arrived or has recently been to a certain area, Graells and colleagues Derek Corcoran and Juan Carlos Aravena reconstructed the date in which trees from different sites across a continental region in southern Chile were attacked by the rodents. The team worked by counting growth rings in the fallen trunks. "It is the first time the technique, known as dendrochronology, is used to date the presence of invasive species," Graells says. The felling of trees is one of the beaver's most damaging habits. The telltale signals from their dirty work are unmistakable: teeth marks around a trunk that has been carved like a pencil tip. You can tell that the attacker was a beaver even if there are no nearby dens.

Next, researchers matched the ages of the attacked trees with the earliest date where beavers were observed across the region. The results were disturbing: The beavers in Tierra del Fuego had already jumped to the continent in 1968, 26 years before they were seen for the first time. "It was quite a surprise," admits Graells, who now believes there might be a true "invisible" expansion of the species, perhaps more pronounced than previously estimated. The find, she adds, could accelerate the need to put control measures in place.

Nonhuman ecosystem engineers
The beaver is the second-largest rodent on Earth: Adults can weigh up to 30 kilograms and measure more than one meter long. Two species of beaver exist today: Castor fiber, from Eurasia; and Castor canadensis, which evolved in North America, the same species that was introduced in Tierra del Fuego. Both species are great ecosystems engineers, modifying their environments by cutting branches and entire tree trunks in order to build dams, canals and dens.

Since the arrival of the beaver the Patagonian Magellanic forest has never been the same: Many of the fallen trees, even if they have been partially cut, are not able to survive the attack whereas North America's trees are more resistant to this kind of damage and can rebound. Beaver-built dams can reach around 100 meters in length and cause floods which have serious impact on acres of native vegetation. And even if a dam is destroyed, the accumulated mud buries the seeds that normally allow for forest regeneration. "Studies have shown that after 20 years the forest is not able to go back to its original state, and it is replaced by introduced grass-loving species," Graells says. The beaver's action also affects roads, sewers, bridges and fences.

When beavers go out of control, their activities can transform the landscape for decades or centuries, even indefinitely, says Marta Lizarralde, a researcher with the Molecular Ecology Laboratory at the Southern Center for Scientific Research (CADIC) in Ushuaia, Argentina. Out of the original population of 20 individuals, it is estimated that today there are between 100,000 and 150,000 beavers in the Fuegian archipelago alone, even though that number is only an indirect approximation, she says.

Could beavers continue to expand north? Recent evidence seems to support that possibility. In a yet-to-be-published fitness model that takes into account the climatic conditions favoring the species propagation, Graells and colleagues forecast that beavers could colonize South America at least up to 43 degrees south latitude, some 1,300 kilometers north of their latest proved location. The expansion would mainly take place west of the Andes Mountains, on the Chilean side.

Another factor feeding this fear is the beaver's ability to reproduce in different habitats, a skill that is surprising researchers. A study in the Patagonian region led by Duke University biologist Alejandro Pietrek showed that the size of the beavers' colonies and the yearly number of offspring are larger in the steppe than in the forest environment. "Beavers are typically associated with forests, but this turns out to be a more plastic species able to populate semiarid regions," Pietrek told Scientific American.

Scientists today know the effects that introduced animal or plant species can have in an ecosystem. But the beaver expansion in Tierra del Fuego out of so few initial specimens represents an extraordinarily successful and unprecedented biological invasion. For example, seven American beavers were freed in Finland in 1937 and a decade ago it was estimated that their number had "only" reached 12.000.

The invasive capacity of the beavers at the end of the world "is huge," Lizarralde notes. Yet, she says there is still no evidence they can advance much farther north on their own "imminently or in the midterm."

But, how can we be sure? According to Graells, the accurate dating of the damaged trees can be useful to assess the rhythm of expansion of these rodents as well as to monitor efforts to contain their numbers. Several specialists think it is impossible to completely eradicate the beaver, except on smaller islands, and that the most practical measure would be to control them with selective traps that can also be used commercially to sell the skins. "We must ameliorate the problem before it is too late," Graells says.

# data[].attributes.attachment_link.title
North American Beaver Invasion Occupies Forests and Steppes in Southern Chile and Argentina

# data[].attributes.attachment_link.description
In 1946 the Argentine Navy imported 10 beaver couples from Canada and set them free in Isla Grande, the deep south of Tierra del Fuego, with the intention of "enriching" the native fauna-and the local fur industry.

# data[].attributes.headline
Here's How Much of Alaska's Permafrost Could Melt

# data[].attributes.subject
Here's How Much of Alaska's Permafrost Could Melt

# data[].attributes.attachment_link.readable_text
Up to a quarter of the permafrost that lies just under the ground surface in Alaska could thaw by the end of the century, releasing long-trapped carbon that could make its way into the atmosphere and exacerbate global warming, a new study finds.

The study, detailed in the journal Remote Sensing of Environment, maps where that near-surface permafrost lies across Alaska in more detail than previous efforts. That detail could help determine where to focus future work and what areas are at risk of other effects of permafrost melt, such as changes to local ecosystems and threats to infrastructure, the study's authors say.

About one quarter of the land in the Northern Hemisphere is permafrost, or ground that stays frozen for at least two years. Some of it has been in that frozen state for thousands of years, locking up an amount of carbon that is more than double what is currently in the Earth's atmosphere. But with temperatures in the Arctic rising at twice the rate of the planet as a whole, permafrost across the region is beginning to thaw, releasing that carbon from its icy confines.

"There's a lot-a lot-of soil carbon that's below ground in these Arctic and boreal systems," U.S. Geological Survey scientist and study co-author Bruce Wylie said. "That's the big threat."

If that carbon makes its way into the atmosphere it could help further drive up global temperatures-already 1°C (nearly 2°F) above pre-industrial temperatures-and intensify the impacts of that warming, such as sea level rise and more prolonged and intense heat waves. It could also ramp up the feedback cycle of warming in the Arctic leading to more and more permafrost melt and still more warming. The additional greenhouse gas contribution from melting permafrost could have a $43 trillion economic impact by 2200, another recent study found.

The permafrost closest to the surface is a big concern because it is particularly susceptible to thaw from rising air temperatures, as well as other factors like flowing water and wildfires. But scientists don't even know where all of the permafrost is located.

By its nature, permafrost is below ground where "you can't see it and you can have really abrupt boundaries," Wylie said. It is also found across large expanses of remote territory-not the easiest areas to study.

To get around these problems, the study team used data from 17,000 spots where permafrost was directly measured in Alaska. They matched those measurements to environmental data like air temperature, precipitation, elevation and other factors, and let a computer algorithm learn those associations and then fill in the rest of the map with a resolution down to about 30 meters, higher than previous efforts.

They found that 38 percent of Alaska has near-surface permafrost. But they didn't stop there.

Using the relationships they established between permafrost and climate factors, the team used their model to fast-forward and see what would happen in the future as overall temperatures rise. (They kept other factors like vegetation and wildfire activity the same as today to isolate the impacts from climate.)

They estimate that between 16 and 24 percent of near-surface permafrost in Alaska would disappear by the end of the century due to climate change alone. Most susceptible was the permafrost of the central portions of Alaska, "the warmer boreal permafrost where the entire thickness of the permafrost can thaw out within a few decades," co-author Torre Jorgenson of Alaska Ecoscience in Fairbanks said in an email.

Warmer temperatures on short timescales can even have a noticeable impact on permafrost, Jorgenson said, "particularly warm winters with deep snow early in the winter, such as this year."

Alaska has had a spate of warm years recently, with 2014 ranking as its hottest year on record, bleeding into this past winter. The cold season of October 2014 to March 2015 was the third warmest on record, according to the National Centers for Environmental Information. This cold season has started out on the toasty side as well, with much of the state having temperatures well above average for October.

"This year will be bad for permafrost stability," Jorgenson said.

The actual amount of near-surface permafrost loss over the century will likely be higher than the study estimates because of other factors like increased wildfire activity and ecosystem feedbacks that could amplify the effects of warming, the scientists say.

For some locations on the new map, the authors are less certain about whether there is permafrost there than they are for others. They hope the map will spur further study where this uncertainty is high to get a clearer picture of the permafrost. It could also help to focus research on the areas where permafrost is considered most vulnerable, for example, because of a particularly thin layer of soil overlying them that is more likely to burn off in a wildfire.

"We are soon reaching a climate warming threshold [where] fires will eliminate permafrost beyond recovery in the boreal region," Jorgenson said.
This article is reproduced with permission from Climate Central. The article was first published on December 8, 2015.

# data[].attributes.attachment_link.title
Here's How Much of Alaska's Permafrost Could Melt

# data[].attributes.attachment_link.description
Up to a quarter of the permafrost that lies just under the ground surface in Alaska could thaw by the end of the century, releasing long-trapped carbon that could make its way into the atmosphere and exacerbate global warming, a new study finds.

# data[].attributes.headline
Howler Monkeys Trade Testicles for Decibels

# data[].attributes.subject
Howler Monkeys Trade Testicles for Decibels

# data[].attributes.attachment_link.readable_text
[ Howler monkey calls]

Howler monkeys. From their Central and South American rainforest home, they produce some of the loudest animal calls in the world. They're about the size of an adult cocker spaniel, but they can sound as large as a tiger.

Biologists have long suspected that the monkeys' howls played a role in attracting mates. The sounds are like the auditory version of peacock feathers or deer antlers that say, hey, check me out.

And now we know that the quality of the howl depends on a bone near their throats called the hyoid. The bigger the hyoid, the deeper the howl. Males with deeper calls sound more attractive to females. Which means that males with smaller hyoids had to come up with another strategy.

"When you're in the field and you look up at the monkeys, you notice that in Alouatta palliata, the mantled howler monkey, that the testes are huge. And they're white, they're really obvious."

University of Utah anthropologist Leslie Knapp. She her team found that howler monkeys face an anatomical trade-off: a species can either have a really big hyoid bone, or it can be very well endowed. But not both. That finding is in the journal Current Biology. [Jacob C. Dunn et al, Evolutionary Trade-Off between Vocal Tract and Testes Dimensions in Howler Monkeys]

Those species with bigger hyoids live in single-male groups, so it makes sense to invest in what the researchers call "precopulatory traits," that is, their courtship strategy of attracting the female's attention.

But in a species where groups include multiple males, the best way to ensure passing on more genes is to make more sperm-by building bigger testes.

The researchers say the finding is the first evidence for an evolutionary trade-off between mating calls and sperm production. And they warn that while human women do tend to prefer males with deeper voices, we men advertise ourselves in many other ways as well. So don't go clicking that pop-up ad that promises to enlarge your hyoid.

-Jason Goldman

[ The above text is a transcript of this podcast.]

[Howler monkey sounds from a video courtesy of La Senda Verde Animal Refuge, Bolivia]

# data[].attributes.attachment_link.title
Howler Monkeys Trade Testicles for Decibels

# data[].attributes.attachment_link.description
Howler monkey calls] Howler monkeys. From their Central and South American rainforest home, they produce some of the loudest animal calls in the world. They're about the size of an adult cocker spaniel, but they can sound as large as a tiger. Biologists have long suspected that the monkeys' howls played a role in attracting mates.

# data[].attributes.headline
Advanced Nuclear Reactors? Don't Hold Your Breath

# data[].attributes.subject
Advanced Nuclear Reactors? Don't Hold Your Breath

# data[].attributes.headline
Cities Along Great Lakes Face Rising Water and Costs

# data[].attributes.subject
Cities Along Great Lakes Face Rising Water and Costs

# data[].attributes.attachment_link.readable_text
Cities on the Great Lakes and St. Lawrence River will face nearly $2 billion in damages from climate change through 2025, according to a new survey of municipalities in the basin.

That's on top of nearly $880 million spent since 2019 as the world's largest freshwater system experiences more extreme weather events, unpredictable swings in lake levels, and changes in precipitation and evaporation rates, officials said.

"High water levels, paired with severe storm events and wave action, are leading to greater erosion and flooding that threaten public and private properties, critical infrastructure, and recreation and tourism amenities in shoreline communities," said Walter Sendzik, chair of the Great Lakes and St. Lawrence Cities Initiative and mayor of St. Catharines, Ontario.

The survey of 241 municipalities - from large cities to villages - found that 99% of responding communities witnessed consistent or rising interest in coastal zone issues, while more than 8 in 10 respondents said water level and flooding forecasts are "very important to their jurisdiction's work on coastal planning."

Yet only 27% of respondents said their municipalities have staff that are "highly knowledgeable" of coastal issues, and only 11% reported having high capacity to respond to such issues.

While the Great Lakes have always seen rising and falling water levels, usually over decadal cycles, and are famously stormy, experts say conditions are becoming more variable and that past events and conditions do not necessarily inform the lakes' future (, March 21, 2019).

In July 2019, for example, water levels on Lake Michigan soared to nearly 3 feet above mean summer levels, causing severe erosion on the lake's eastern shore where homes sit perilously close to the water's edge (Climatewire, Aug. 22, 2019).

Big cities like Chicago and Milwaukee also have seen infrastructure damage from high water, wave action and seasonal storms (Climatewire, Nov. 26, 2019). Lake Erie faces perennial risk from toxic algae blooms, a problem linked to agricultural runoff and warmer water temperatures (Climatewire, Nov. 1, 2019).

Don Wuebbles, professor of atmospheric science at the University of Illinois and a nationally recognized expert on the Great Lakes, said climate change will affect shoreline communities in various ways, most notably rising and falling lake levels due to changes in precipitation and evaporation.

"What sounds like global warming is not just a trivial increase in temperature, it really is about extreme events," he said.

The Great Lakes cities initiative, along with other regional organizations, say funding from federal, state and local governments - in both the United States and Canada - will be essential to help communities adapt to changing conditions.

The Biden administration's $1.2 trillion infrastructure package, currently before Congress, could provide critical funding for adaptation and resilience projects, officials said. "Our coastal infrastructure is vital to the economic and recreational health of our communities, and coordinated action is required," Milwaukee Mayor Tom Barrett (D) said in a statement.
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides essential news for energy and environment professionals.

# data[].attributes.attachment_link.title
Cities along the Great Lakes Face Rising Water and Costs

# data[].attributes.attachment_link.description
Cities on the Great Lakes and St. Lawrence River will face nearly $2 billion in damages from climate change through 2025, according to a new survey of municipalities in the basin. That's on top of nearly $880 million spent since 2019 as the world's largest freshwater system experiences more extreme weather events, unpredictable swings in lake levels, and changes in precipitation and evaporation rates, officials said.

# data[].attributes.headline
Soaring Temperatures and Wildfire Threaten California's Power Grid

# data[].attributes.subject
Soaring Temperatures and Wildfire Threaten California's Power Grid

# data[].attributes.attachment_link.readable_text
Extreme heat and a wildfire in Oregon pushed California to the brink of switching off power to thousands of people over the weekend as climate-related disasters affect communities across the parched western United States.

Flames from the Bootleg Fire in Oregon threatened an electricity inner tie that sends power to Northern California, eliminating about 5,500 megawatts of power bound for the Golden State. That's equivalent to the generating capacity of about 10 large natural gas-fired power plants.

The California Independent System Operator, the state's grid manager, warned Saturday that it might fail to maintain its operating reserve of 3,000 MW. It urged residents to limit their use of electricity as a severe heat wave sent temperatures skyrocketing across large portions of the West.

"Many of us are really recognizing now that climate change and these extreme heat waves happening in the earlier parts of the summer now have forced all of us to do things that we really never imagined just a few years ago," ISO President and CEO Elliot Mainzer said during a briefing with reporters. "We've entered this new normal. And now it's really going to take all of us doing our own part during this important clean energy transition to keep the lights on."

It was reminiscent of a sizzling period last summer, when the ISO forced rolling power outages in mid-August as power demand soared during a heat wave. An analysis later blamed the outages on a lack of long-term planning (Energywire, Jan. 14).

Since then, the ISO and the California Public Utilities Commission have been working to boost power supplies. But that comes as the state moves to transform its grid into a delivery network of 100% clean power, with a goal of reaching carbon neutrality by 2045.

California Gov. Gavin Newsom (D) on Saturday signed an executive order suspending certain environmental requirements around power production. It enabled the use of more portable generators and auxiliary ship engines, and he temporarily waived air quality and other restrictions on power generating plants.

It's a difficult start to summer on the West Coast. Record heat blanketed the Pacific Northwest and British Columbia in late June. Temperatures at the time soared to 121 degrees Fahrenheit in Lytton, British Columbia, a village northeast of Vancouver that was burned to the ground by a wildfire days later. Portland, Ore., hit a new record of 116 F two weeks ago, and temperatures at Seattle-Tacoma International Airport soared to 107 F, the highest temperature ever recorded in the area.

Hundreds died from the June heat. The coroner's office in British Columbia said 719 deaths were reported between June 25 and July 1, three times the normal amount. The extreme heat "is a significant contributing factor to the increased number of deaths," Lisa Lapointe, chief coroner, said at the time.

Over the weekend, temperatures soared in parts of California and Nevada. Death Valley, Calif., reached 130 degrees Fahrenheit on Friday, matching a high set last August (Climatewire, Aug. 18, 2020).

Before then, such heat had not been seen anywhere in the world since the 1930s.

Blazing hot temperatures are not uncommon for Death Valley, which holds the record for being the hottest place on Earth. It reportedly hit 134 degrees on July 10, 1913. The accuracy of that figure has been disputed, but the World Meteorological Organization "is the steward of the world records, and they've not challenged the 134 F," said Chelsea Peters, a National Weather Service meteorologist in Nevada.

High temperatures broke records in other parts of California over the weekend. Needles, a city near the Mohave Desert, reached 122 F, one degree higher than its hottest-ever reading in 2003.

Las Vegas on Saturday tied an all-time record at 117 degrees. The city has hit that four times previously, most recently in 2017.

High temperatures and the power demands resulting from them are raising concerns early in the summer.

"We ... came into this summer thinking that our issues were primarily going to be associated with August and September," said Mainzer, the ISO official. "And we had the first major ... heat wave four days before the official beginning of summer."
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides essential news for energy and environment professionals.

# data[].attributes.attachment_link.title
Soaring Temperatures and Wildfire Threaten California’s Power Grid

# data[].attributes.attachment_link.description
Extreme heat and a wildfire in Oregon pushed California to the brink of switching off power to thousands of people over the weekend as climate-related disasters affect communities across the parched western United States. Flames from the Bootleg Fire in Oregon threatened an electricity inner tie that sends power to Northern California, eliminating about 5,500 megawatts of power bound for the Golden State.

# data[].attributes.headline
Half of All Amphibian Species At Risk of Extinction

# data[].attributes.subject
Half of All Amphibian Species At Risk of Extinction

# data[].attributes.attachment_link.title
Half of all amphibian species at risk of extinction

# data[].attributes.attachment_link.description
A new study finds that more than 1,000 amphibian species poorly known to science are likely facing extinction, adding to the already identified 4,200 species the UN says are in peril.

# data[].attributes.attachment_link.readable_text
Extinction is a natural phenomenon: After all, more than 90 percent of all organisms that have ever lived on Earth aren't alive today.

But humans have made it worse, accelerating natural extinction rates due to our role in habitat loss, climate change, invasive species, disease, overfishing, and hunting.

"We're losing whole suites of species that have distinct ecological roles to play," says Stuart Pimm, Professor of Conservation at Duke University. For instance, top predators such as sea otters and sharkshave dwindled, throwing their ecosystems off-kilter.

Dozens of new species go extinct every day, and scientists say that more than 20,000 plants and animals are on the brink of disappearing forever. A quarter of known mammal species is at risk of extinction.

The main body that tracks species decline is the International Union for the Conservation of Nature. The organization evaluates species in the wild, and, along with data from a variety of sources, categorizes their vulnerability on its Red List of Threatened Species.

Here are some terms and concepts that biologists use when talking about extinction.

Critically endangered

These animals are facing a high probability of extinction. These species include the Sumatran rhinoceros and the Sumatran orangutan, whose habitat is being destroyed by logging and agriculture.

Extinct in the wild

These are species that no longer live in their native range, and exist only in captive environments such as zoos or breeding centers. In 1987, the 27 California condors left in the world were taken into captivity, making them extinct in the wild.

The Guam rail, a small, flightless bird, was nearly driven to extinction by the invasive brown tree snake, which was accidentally brought to the island by the U.S. military. The rails now live only in captive environments, including the National Aviary in Pittsburgh.

Locally extinct

This isn't an IUCN category, but a term meaning an animal is gone from part of its native range. Grizzly bears are locally extinct in California, but still live in the wild in other areas.

The American pika, a cold-loving relative of rabbits, is often erroneously reported to be moving to higher locations as the climate warms. It's true that the species is locally extinct-also referred to as extirpated-in some areas within the Great Basin Mountains of the western U.S, but a 2018 study in the journal Arctic, Antarctic and Alpine Research found that pikas are adaptable, and still persist throughout the region.

"Pikas can be highly resilient, and continue to surprise us by their occupancy at hot, low-elevation sites," Andrew Smith, co-chair of the IUCN Lagomorph Specialist Group, says via email. This species is listed as "of least concern" on the IUCN Red List.

In New England, less snowy winters are allowing a species of tick to live longer, which is in turn killing off the region's moose. With their skinny necks, emaciated bodies, and big, hairless splotches, these "ghost moose" look like the walking dead as they stumble through the forest.

Functionally extinct

This term means there are too few members of a species to perform its function in the ecosystem, says Steve Beissinger, a professor of conservation biology at the University of California, Berkeley.

For instance, American chestnut trees were once widespread throughout North America, but a fungus killed 3.5 billion of them in the early 20th century. A few trees survived, making the species functionally extinct.

Extinct

This IUCN category means a species is "globally extinct," or "gone everywhere," Beissinger says, a determination made after time and exhaustive searches in their habitat.

Hunting and habitat loss likely wiped out the colorful Carolina parakeet, which was once abundant in the U.S. and is now officially extinct. These birds were especially vulnerable since they didn't flee gunfire, but stayed with their wounded comrades, according to the Cornell Lab of Ornithology.

Extinct species rediscovered

Sometimes animals thought to be extinct emerge alive, often thanks to targeted surveys in remote habitats.

These so-called "Lazurus species" usually haven't been seen in decades in their normal ranges, but may turn up in an unexpected place or just be hard to detect due to low populations.

In 2010, Conservation International and the IUCN's Amphibian Specialist Group launched an effort to seek out 10 extinct amphibian species of high scientific and aesthetic value. The search did rediscover a few species, including the Hula painted frog.

Sometimes species are endangered even as they're discovered.

The Manduriacu glass frog of the Ecuadorian Andes was newly discovered in mining area, so its survival is already dubious.
On June 7, this story was updated to correct inaccuracies about the American pika. The animal is not moving to higher elevations as the climate warms.

# data[].attributes.attachment_link.title
What is extinction? The answer is complicated.

# data[].attributes.attachment_link.description
Extinction is a natural phenomenon: After all, more than 90 percent of all organisms that have ever lived on Earth aren't alive today. But humans have made it worse, accelerating natural extinction rates due to our role in habitat loss, climate change, invasive species, disease, overfishing, and hunting.

# data[].attributes.headline
A Closer Look At Lion Evolution Offers Hope For Saving The Big Cats

# data[].attributes.subject
A Closer Look At Lion Evolution Offers Hope For Saving The Big Cats

# data[].attributes.attachment_link.readable_text
Thirty-thousand years ago, different types of lions prowled the globe, hunting prey on four continents. One of the most prolific, the cave lion, roamed from Spain all the way through Eurasia and into modern-day Alaska and the Yukon and was widely depicted in prehistoric cave art.

Meanwhile, the American lion, which was even larger than African lions and saber-toothed tigers, lurked throughout North America and possibly parts of South America. Other lions of various sizes and appearances inhabited Africa, the Middle East, and India. Most of these creatures have since disappeared, but scientists have been able to glean genetic clues that shed new light on them and offer insights into their modern cousins, which now facing their own extinction.

Over the past 150 years, the global population of African lions has declined by more than 20-fold to fewer than 25,000, mostly due to hunting and habitat loss. Roughly 600 Asiatic lions remain in India.

To help save the world's remaining lions and better understand how the different types are related, an international team of scientists created complete genomes of 20 individual lions, 14 of which died long ago, including two 30,000-year-old cave lions preserved in permafrost in Siberia and the Yukon.

In the study, published May 4 in Proceedings of the National Academy of Sciences, researchers discovered that cave lions didn't interbreed with other types of lions, found that Asiatic lions split off from their ancestors about 70,000 years ago, and other secrets of the big cat's evolution.

The paper "looks into the past to inform the future," says co-author Ross Barnett, a geneticist with the University of Copenhagen. "If you were to just look at the lions around today, you'd miss the story."

Out of Africa

The study's results support the idea that lions radiated out of Africa in a series of migrations, somewhat analogous to humans, Barnett says.

Cave lions came out first, splitting from their African kin about 500,000 years ago, according to the paper. These lions then evolved slightly different characteristics. For example, we know "from good cave art in Europe that the males didn't have manes," Barnett says. They spread throughout Eurasia, and into North America.

Surprisingly, though, cave lions and ancestors of today's African lions didn't interbreed, the genetic analysis reveals. That's odd because most big cats are known to occasionally mate when given the chance-even very different animals, like lions and tigers, says study co-author Marc de Manuel, with the Institute of Evolutionary Biology in Barcelona.

It seems likely, then, that there was something preventing them from mixing-and not just geography, since their ranges overlapped for a while in southwestern Asia.

Barnett says this may have been because cave lions did not have manes, which female African lions recognize as important signals of fitness and virility. Possibly, then, other types of lions didn't view the male cave lions as viable mates, he says. ( Read about a rare lion with a black mane.)

Another migration and separation occurred when the ancestors of Asiatic lions split off about 70,000 years ago. These lions once ranged from Saudi Arabia to India. Now, the small, isolated population in western India's Gir Forest is all that's left, says Steve O'Brien, a research scientist with Nova Southeastern University.

Thanks to conservation efforts, the population has expanded nearly threefold since the 1990s, but the population is highly inbred, with a low level of genetic diversity. As a result, male Asiatic lions have malformed sperm and testosterone levels about 10 times lower than those of African lions, O'Brien says.

It will perhaps be necessary one day to introduce fresh genes into the population if more genetic diversity is lost, but that could be politically difficult and controversial, Barnett says. ( Read more about Asiatic lions and their recovery.)

Extinct cats

As part of the study, the researchers assembled genomes of individuals from three other extinct lineages: Barbary lions of North Africa; Middle Eastern lions; and Cape lions of South Africa. All three had slight variations in appearance, though the new genetic information shows they don't qualify as different species.

Their work mostly supports the current dominant view that there two lion subspecies: Asiatic lions and the populations in Central and West Africa are currently classified together as Panthera leo leo, and the animals in East and South Africa are known as Panthera leo melanochaita. However, the paper suggests the Central African lions, of which there are only a couple hundred remaining, may be more closely related to East and Southern African lions, though more work is needed to confirm that finding.

Scientists have suggested reintroducing lions to West Africa, where they're critically endangered; there are only about 400 remaining.

Because West African lions are most genetically similar to the extinct Barbary lions, the study found, West Africa could provide a good source population if any reintroduction efforts gained momentum-though that is a still an unlikely scenario.

Preventing lion loss

In the past, lions were widespread and, apart from the cave lions, different populations intermingled enough to spread around genes, which is crucial to the species' long-term health.

This study reinforces the importance of having large protected areas of contiguous habitat to allow gene flow and protecting animals from hunting, the authors say. It also adds urgency to conserving lions and protecting against future losses.

One sobering takeaway: The paper shows that Barbary lions had relatively healthy levels of genetic diversity before disappearing, suggesting that their extinction happened quickly in evolutionary terms, de Manuel says-a possible outcome for the lions of today if their conservation isn't prioritized.

# data[].attributes.attachment_link.title
A closer look at lion evolution offers hope for saving the big cats

# data[].attributes.attachment_link.description
Thirty-thousand years ago, different types of lions prowled the globe, hunting prey on four continents. One of the most prolific, the cave lion, roamed from Spain all the way through Eurasia and into modern-day Alaska and the Yukon and was widely depicted in prehistoric cave art.

# data[].attributes.attachment_link.description
Deserts may seem lifeless, but in fact many species have evolved special ways to survive in the harsh environments.

# data[].attributes.headline
Invasive Grass is Overwhelming U.S. Deserts - Providing Fuel For Wildfires

# data[].attributes.subject
Invasive Grass is Overwhelming U.S. Deserts - Providing Fuel For Wildfires

# data[].attributes.attachment_link.readable_text
In recent years, large swathes of the desert landscape in the parks around Tucson, Arizona have started to look a lot like grassland. And that's a problem.

Buffelgrass, a perennial arid climate-adapted grass from Africa, was brought to the United States in the 1930s and planted throughout Arizona, Texas, and Mexico to control soil erosion and provide cattle forage. In the 1980s, it started to take over the Sonoran Desert-including state and national parks-causing a multitude of ecological issues and fueling wildfires.

In Arizona, the problem is so severe that the grass is officially labeled a noxious weed, but the grass has spread to numerous states from Hawaii to Florida. It shades the ground as it multiplies, which prevents the growth of other species of seedlings.

Buffelgrass "will invade undisturbed desert; it doesn't require disturbance," says Kim Franklin, a conservation research scientist at the Arizona-Sonora Desert Museum in Tucson. "It'll invade Saguaro National Park and Coronado National Forest and it will out-compete the native plants."

Public lands in southern Arizona preserve the important Sonoran Desert ecosystem and draw hundreds of thousands of people a year for hiking and recreation. Many of those people are locals who have decided to fight back and protect the environment-and their homes.

Volunteers to the rescue

About a dozen volunteers of all ages, from teenager to retiree, came together on a cool winter weekend morning to remove buffelgrass from a small patch of Catalina State Park, a popular, 5,500-acre Tucson park that gets over 200,000 visitors a year. With long, metal pickaxes in hand, the Catalina State Park Buffel Slayers spent the morning hard at work without much chit-chatting. The air was filled not with talking, but the sounds of soft grunts and the thud of pick axes hitting bunches of dry grass.

Gray, gnarled clumps of buffelgrass about a foot high and a foot wide cover the rocky hillside like a scratchy carpet, filling the gaps between granite boulders and crowding the base of towering saguaro cactus and smooth, green palo verde trees. A spray of green tendrils in the center of each plant shows a faint sign of life in a pile of grass that otherwise looks dead.

The buffelgrass has firmly taken hold in this patch of the park. "It doesn't get any worse than this," says Joe Ciaramitaro, who has been volunteering to pull grass for 10 years, sometimes multiple days per week now that he's retired.

Buffelgrass is hard to beat. There are two major lines of defense against this grass: chemical sprays and manual removal. Herbicides are only effective when the plant is green during the summer, which coincides with the hottest days in the desert, so year-round manual buffelgrass pulls have become critical in keeping it out of parks.

Perry Grissom, the restoration ecologist at Saguaro National Park, says that people, like himself, who study invasive species can "see a train wreck before it's happened, so the hard part is getting other people to see that train wreck." Luckily, volunteers from the region have stepped up to help. (Visitors are also allowed to sign up for buffelgrass pulls.)

The grass has well-anchored roots that need to be removed to eradicate the plant, so it's no walk in the park. Volunteers need to wield a crowbar or a pickaxe to get it out completely.

If the plant is gone, the remaining seeds can be viable for years, so even if an area is cleared once, it needs repeat visits. Patty Estes founded the Buffel Slayers volunteer group that works in Catalina State Park, and she says she "doesn't relax until after three years."

The Buffel Slayers have been around for five years, but the Sonoran Desert Weed Wackers have been out wrestling with buffelgrass in Tucson Mountain Park since 2000. Kim Franklin says their consistent effort has made a huge difference and kept the issue under control in the park.

The volunteers are passionate. Joe Ciaramitaro, who says he "gets kind of crazy" about pulling grass, volunteers with the Weed Wackers, the Buffel Slayers, and also just on his own. He says there's one part of Pima Canyon in Tucson that he has weeded solo over the past seven years; it adds up to around 60 acres.

Fuel for the fire

Invasive plants don't just threaten iconic species by crowding them out-they also can cause them to go up in smoke. Exotic grasses grow between cactus, trees, bushes, and rocks in soil that would normally be devoid of plants. With a thick mat of prime fuel, fire can easily spread after a lightning strike or careless campfire.

"It's a primary resource threat to the desert part of the park, really, and that's mainly because of fire," says Grissom. He says about 90 percent of the invasive species management he deals with is buffelgrass.

Buffelgrass is not the only grass problem around the Southwest, Grissom cautions. Other exotic grasses that were once planted in gardens or for forage, such as lovegrass and red brome, are turning the desert into a tinderbox. These grasses, along with other invasive plants such as stinknet, have provided fuel for some of the largest fires in Arizona in recent years.

In 2020, the state had one of its worst wildfire seasons in a decade, due to massive fires such as the Bush Fire in Tonto National Forest near Phoenix. Grissom says that invasive plants fed the flames of this over 193,000-acre blaze, the fifth largest in state history. This does not bode well for the Southwest: Recent research shows Arizona and New Mexico rank the highest on a vulnerability index for places at high risk of wildfire.

"So the desert historically didn't burn," Grissom says. "The best guess is [that] a single spot might burn every 250 years or longer." Prescribed burns show that fires fueled by buffelgrass burn much hotter and spread faster than typical desert fires.

"Saguaros, palo verdes, they did not evolve with fire. They don't really have protection from fire," he says.

The diminishing number of native plants is a major threat to the region's ecosystem and tourism. Franklin says research shows that although there are fewer young saguaros now, because saguaros can live for over a hundred years, future generations might be the ones noticing the decline.

For some of the volunteers, the motivation is clear: There are still visible scars from last year's Bighorn Fire, which closed Catalina State Park for a month. Many remember the fear they felt as the 120,000-acre fire threatened their homes nearby.

Beyond burn scars, signs of success are visible, if you know where to look. Estes says some of the areas they've cleared out in Catalina State Park have remained free of buffelgrass and are now full of wildflowers in the spring.

While buffelgrass will never be completely eradicated in the Southwest-it likely covers around five million acres in the state of Sonora, Mexico alone-all hope is not lost.

"We can't eradicate it, but we can control it. Because if we don't control it, then we lose these amazing saguaro forests," Franklin says.

Shaena Montanari is an environmental journalist based in Phoenix, Arizona. Follow her on Twitter.

# data[].attributes.attachment_link.title
Invasive grass is overwhelming U.S. deserts-providing fuel for wildfires

# data[].attributes.attachment_link.description
In recent years, large swathes of the desert landscape in the parks around Tucson, Arizona have started to look a lot like grassland. And that's a problem. Buffelgrass, a perennial arid climate-adapted grass from Africa, was brought to the United States in the 1930s and planted throughout Arizona, Texas, and Mexico to control soil erosion and provide cattle forage.

# data[].attributes.headline
Setbacks in Development and Family Planning Slow Progress Along the Demographic Transition

# data[].attributes.subject
Setbacks in Development and Family Planning Slow Progress Along the Demographic Transition

# data[].attributes.attachment_link.title
World Population Day 2021 - Setbacks in Development and Family Planning Slow Progress Along the Demographic Transition

# data[].attributes.attachment_link.description
Globally, the demographic transition from high to low fertility and mortality has improved quality of life for billions of people over the past several decades. The average number of children born per woman worldwide decreased from nearly 5 in 1950 to 2.47 by 2020.

# data[].attributes.headline
Nigeria's Electronic Waste is a Public Health Problem and Needs Urgent Attention

# data[].attributes.subject
Nigeria's Electronic Waste is a Public Health Problem and Needs Urgent Attention

# data[].attributes.headline
Male Fertility is Declining - Studies Show That Environmental Toxins Could Be a Reason

# data[].attributes.subject
Male Fertility is Declining - Studies Show That Environmental Toxins Could Be a Reason

# data[].attributes.attachment_link.readable_text
In the U.S., nearly 1 in 8 couples struggles with infertility. Unfortunately, physicians like me who specialize in reproductive medicine are unable to determine the cause of male infertility around 30% to 50% of the time. There is almost nothing more disheartening than telling a couple "I don't know" or "There's nothing I can do to help."

Upon getting this news, couple after couple asks me questions that all follow a similar line of thinking. "What about his work, his cellphone, our laptops, all these plastics? Do you think they could have contributed to this?"

What my patients are really asking me is a big question in male reproductive health: Does environmental toxicity contribute to male infertility?

Male fertility decline

Philippe Roy/Cultura via Getty Images

Infertility is defined as a couple's inability to get pregnant for one year despite regular intercourse. When this is the case, doctors evaluate both partners to determine why.

For men, the cornerstone of the fertility evaluation is semen analysis, and there are a number of ways to assess sperm. Sperm count - the total number of sperm a man produces - and sperm concentration - number of sperm per milliliter of semen - are common measures, but they aren't the best predictors of fertility. A more accurate measure looks at the total motile sperm count, which evaluates the fraction of sperm that are able to swim and move.

A wide range of factors - from obesity to hormonal imbalances to genetic diseases - can affect fertility. For many men, there are treatments that can help. But starting in the 1990s, researchers noticed a concerning trend. Even when controlling for many of the known risk factors, male fertility appeared to have been declining for decades.

In 1992, a study found a global 50% decline in sperm counts in men over the previous 60 years. Multiple studies over subsequent years confirmed that initial finding, including a 2017 paper showing a 50% to 60% decline in sperm concentration between 1973 and 2011 in men from around the world.

These studies, though important, focused on sperm concentration or total sperm count. So in 2019, a team of researchers decided to focus on the more powerful total motile sperm count. They found that the proportion of men with a normal total motile sperm count had declined by approximately 10% over the previous 16 years.

The science is consistent: Men today produce fewer sperm than in the past, and the sperm are less healthy. The question, then, is what could be causing this decline in fertility.

Mm Zaletel/Wikimedia Commons, CC BY-SA

Environmental toxicity and reproduction

Scientists have known for years that, at least in animal models, environmental toxic exposure can alter hormonal balance and throw off reproduction. Researchers can't intentionally expose human patients to harmful compounds and measure outcomes, but we can try to assess associations.

As the downward trend in male fertility emerged, I and other researchers began looking more toward chemicals in the environment for answers. This approach doesn't allow us to definitively establish which chemicals are causing the male fertility decline, but the weight of the evidence is growing.

A lot of this research focuses on endocrine disrupters, molecules that mimic the body's hormones and throw off the fragile hormonal balance of reproduction. These include substances like phthalates - better known as plasticizers - as well as pesticides, herbicides, heavy metals, toxic gases and other synthetic materials.

Plasticizers are found in most plastics - like water bottles and food containers - and exposure is associated with negative impacts on testosterone and semen health. Herbicides and pesticides abound in the food supply and some - specifically those with synthetic organic compounds that include phosphorus - are known to negatively affect fertility.

Air pollution surrounds cities, subjecting residents to particulate matter, sulfur dioxide, nitrogen oxide and other compounds that likely contribute to abnormal sperm quality. Radiation exposure from laptops, cellphones and modems has also been associated with declining sperm counts, impaired sperm motility and abnormal sperm shape. Heavy metals such as cadmium, lead and arsenic are also present in food, water and cosmetics and are also known to harm sperm health.

Endocrine-disrupting compounds and the infertility problems they cause are taking a significant toll on human physical and emotional health. And treating these harms is costly.

National Institutes of Health

The effects of unregulated chemicals

A lot of chemicals are in use today, and tracking them all is incredibly difficult. Today, more than 80,000 chemicals are registered with the National Toxicology Program. When the program was founded in 1978, 60,000 of those were grandfathered into the program with minimal information, and nearly 2,000 new chemicals are introduced each year. Many scientists believe that the safety testing for health and environmental risks is not strong enough and that the rapid development and introduction of new chemicals challenges the ability of organizations to test long-term risks to human health.

Current U.S. national toxicology regulations follow the principle of innocent until proved guilty and are less comprehensive and restrictive than similar regulations in Europe, for example. The World Health Organization recently identified 800 compounds capable of disrupting hormones, only a small fraction of which have been tested.

A trade group, the American Chemistry Council, says on its website that manufacturers "have the regulatory certainty they need to innovate, grow, create jobs and win in the global marketplace - at the same time that public health and the environment benefit from strong risk-based protections."

But the reality of the current regulatory system in the U.S. is that chemicals are introduced with minimal testing and taken off the market only when harm is proved. And that can take decades.

Dr. Niels Skakkebaek, the lead researcher on one of the first manuscripts on decreasing sperm counts, called the male fertility decline a "wake-up call to all of us." My patients have provided a wake-up call for me that increased public awareness and advocacy are important to protect global reproductive health now and in the future. I'm not a toxicologist and can't identify the cause of the infertility trends I'm seeing, but as physician, I am concerned that too much of the burden of proof is falling on the human body and people who become my patients.

# data[].attributes.attachment_link.title
Male fertility is declining - studies show that environmental toxins could be a reason

# data[].attributes.attachment_link.description
In the U.S., nearly 1 in 8 couples struggles with infertility. Unfortunately, physicians like me who specialize in reproductive medicine are unable to determine the cause of male infertility around 30% to 50% of the time. There is almost nothing more disheartening than telling a couple "I don't know" or "There's nothing I can do to help."

# data[].attributes.headline
Colorado's Unrelenting Ozone Pollution Could Mean Long-Term Problems For Your Health

# data[].attributes.subject
Colorado's Unrelenting Ozone Pollution Could Mean Long-Term Problems For Your Health

# data[].attributes.attachment_link.readable_text
Non-stop ozone can increase the risk of dying from heart and lung diseases, and can decrease birth weights.

Recent research has underscored the consequences of an unrelenting dose of ozone. The potential consequences are far worse than bunions.

A 2019 study compared long-term average ozone exposure with federal mortality data. It found breathing in more of the pollutant appeared to increase the risk of dying from heart and lung diseases. Other research found people living in areas with high ozone pollution are more likely to develop acute respiratory distress syndrome, a severe condition where the lungs fill with fluid.

Another California study looked into the effect on pregnancies. It found birth weights decreased about 1.7 ounces pounds for every 12 part per billion increase in average ozone levels.

A critical review of multiple studies on long-term ozone pollution found exact consequences of prolonged ozone pollution aren't entirely clear. For example, it found scientists had not clearly linked the problem with asthma development in children, but it appears to increase the risk of adult-onset asthma in men.

Gerber said those scientific limitations should not come as a surprise. It's comparatively easy to find the short-term effects of ozone levels on emergency room visits, but it's far harder to measure the impact of pollution over decades.

"The fact they have found any risk is actually remarkable because you can imagine the complexity of these studies," Gerber said.

Ozone needs heat and sunlight to form, so cooler and cloudier days are also ozone-lite days.

In the short term, it appears some relief is headed to the Front Range. Frank Flocke, an atmospheric scientist at the National Center for Atmospheric Research, said a cold front appears to be headed toward the Front Range this weekend.

The shift in weather will likely take away one of the critical ingredients for ozone. Unlike more direct pollutants, the pollutant forms in the atmosphere from volatile organic compounds and nitrogen oxides. Heat and sunlight spur the reaction.

With cooler weather and cloud cover, the Front Range will likely get a break from its streak of high ozone days, but possibly not for long.

# data[].attributes.attachment_link.title
Colorado's Unrelenting Ozone Pollution Could Mean Long-Term Problems For Your Health

# data[].attributes.attachment_link.description
Recent research has underscored the consequences of an unrelenting dose of ozone. The potential consequences are far worse than bunions. A 2019 study compared long-term average ozone exposure with federal mortality data. It found breathing in more of the pollutant appeared to increase the risk of dying from heart and lung diseases.

# data[].attributes.headline
What is La Nina? Does it bring more snow? How climate pattern could affect US weather

# data[].attributes.subject
What is La Nina? Does it bring more snow? How climate pattern could affect US weather

# data[].attributes.attachment_link.readable_text
La Niña means "little girl," while El Niño means "little boy," or "Christ child."

The entire natural climate cycle is officially known by climate scientists as El Niño - Southern Oscillation (ENSO).

A typical La Niña winter in the U.S. brings cold and snow to the Northwest and unusually dry conditions to most of the southern tier of the U.S.

So what exactly is La Niña?

The La Niña climate pattern is a natural cycle marked by cooler-than-average ocean water in the central Pacific Ocean. It is one of the main drivers of weather in the United States and around the world, especially during the late fall, winter and early spring.

It's the opposite to the more well-known El Niño, which occurs when Pacific ocean water is warmer than average.

Both are Spanish language terms: La Niña means "little girl," while El Niño means "little boy," or "Christ child." South American fishermen first noticed periods of unusually warm water in the Pacific Ocean in the 1600s, the National Oceanic and Atmospheric Administration said. The full name they used was "El Niño de Navidad" because El Niño typically peaks around December.

The entire natural climate cycle is officially known by climate scientists as El Niño - Southern Oscillation (ENSO), a see-saw dance of warmer and cooler seawater in the central Pacific Ocean.

During La Niña events, trade winds are even stronger than usual, pushing more warm water toward Asia, NOAA said. Off the west coast of the Americas, upwelling increases, bringing cold, nutrient-rich water to the surface.

These cold waters in the Pacific push the jet stream northward, which affects weather patterns in the U.S. and globally.

What is a La Niña winter?

A typical La Niña winter in the U.S. brings cold and snow to the Northwest and unusually dry conditions to most of the southern tier of the U.S., according to NOAA's Climate Prediction Center. The Southeast and Mid-Atlantic also tend to see warmer-than-average temperatures during a La Niña winter.

New England and the Upper Midwest into New York tend to see colder-than-average temperatures, the Weather Channel said.

Because La Niña shifts storm tracks, it often brings more snow to the Ohio and Tennessee valleys. "Typically La Niña is not a big snow year in the mid-Atlantic," said Mike Halpert, deputy director of the Climate Prediction Center. "You have a better chance up in New England."

Texas A&M University agricultural economist Bruce McCarl said La Niña years are often bad for agriculture in Texas and the surrounding region. U.S. production of most crops - except corn - generally goes down in La Niña years, according to research by McCarl.

Globally, La Niña often brings heavy rainfall to Indonesia, the Philippines, northern Australia and southern Africa.
What to expect: La Niña climate pattern should return this fall and last through winter. Here's what to expect.
During La Niña, waters off the Pacific coast are colder and contain more nutrients than usual. This environment supports more marine life and attracts more cold-water species, such as squid and salmon, to places like the California coast.

Can La Niña worsen the Atlantic hurricane season?

Yes, according to the Climate Prediction Center. "La Niña can contribute to an increase in Atlantic hurricane activity by weakening the wind shear over the Caribbean Sea and tropical Atlantic Basin, which enables storms to develop and intensify," Halpert said in 2020.

Vertical wind shear refers to the change in wind speed and direction between roughly 5,000-35,000 feet above the ground, NOAA said. Strong vertical wind shear can rip a developing hurricane apart, or even prevent it from forming. This is what can happen in the Atlantic during an El Niño when Atlantic hurricane activity is often suppressed.

While La Niña tends to increase hurricanes in the Atlantic, it also tends to decrease their numbers in the eastern and central Pacific Ocean basins.

# data[].attributes.attachment_link.title
What is La Niña? Does it bring more snow? How climate pattern could affect US weather.

# data[].attributes.attachment_link.description
La Niña means "little girl," while El Niño means "little boy," or "Christ child." The entire natural climate cycle is officially known by climate scientists as El Niño - Southern Oscillation (ENSO). A typical La Niña winter in the U.S. brings cold and snow to the Northwest and unusually dry conditions to most of the southern tier of the U.S.