09 May 2014:
Biodiversity, But Not Community
Composition, Surprisingly Stable Over Time
A major turnover of species in habitats around the globe is underway, resulting in the creation of novel biological communities, but overall species diversity is much more
stable than scientists had believed, according to a new report
in the journal Science
. In a survey of 100 long-term biodiversity monitoring projects in a variety of habitats around the world, the authors found that the majority of those studies (59 percent) documented increasing species richness. Biodiversity declined in 41 percent of the studies, but, in all cases the overall change in biodiversity was modest, the researchers said. When looking at changes in the species constituting those communities, however, the researchers found a surprisingly high rate of change — an average of about 10 percent change per decade. "A main policy application of this work is that we're going to need to focus as much on the identity of species as on the number of species," one of the study's authors said. "The number of species in a place may not be our best scorecard for environmental change."
05 May 2014:
New European Satellites
To Give More Detailed Views of Earth
The European Space Agency has begun launching
a series of satellites designed to collect detailed environmental data around the globe — from radar-based, high-definition imagery to information about the
atmosphere's chemical composition. The first satellite in the ESA's Copernicus program, the Sentinel 1A, was launched last month and has already returned many striking images based on radar data, such as this view of Brussels, Belgium, in which the dense urban area contrasts with the city's heavily vegetated surroundings. Once Sentinel satellite 1B is launched next year, the two will be able to map the entire globe in six days, giving researchers and conservationists a powerful way to monitor both short- and long-term changes in the environment. Four additional groups of satellites are set to launch this year. Those arrays will focus on high-resolution photo imagery, topography, surface temperatures, and atmospheric chemistry.
25 Apr 2014:
Soils Release Far More CO2
Than Previously Thought, Researchers Find
As atmospheric CO2 levels rise, soils will likely store less carbon than scientists and climate models had predicted, according to new research
published in Science
. Scientists have long understood that rising carbon dioxide concentrations in the atmosphere spur
photosynthesis and plant growth, adding more carbon to the soil. Scientists had thought this soil carbon was relatively stable and could remain locked away
for centuries. But the new study, from researchers at Northern Arizona University shows that increasing soil carbon actually spurs microbes to produce more CO2. Higher atmospheric CO2 levels added roughly 20 percent more carbon to the soil, through increased photosynthesis, but they also increased carbon turnover by microbes by 16.5 percent. Many climate models had assumed that far more of the carbon absorbed by soils stayed there for long periods of time. "Our findings mean that nature is not as efficient in slowing global warming as we previously thought," the lead researcher said.
24 Apr 2014:
Browning of Congo Rainforest
Is Depicted in NASA Satellite Data
Persistent drought has taken a major toll on Africa's Congo rainforest, with large-scale browning intensifying and affecting a growing portion of the forest over the past decade, an analysis of NASA satellite data shows
browning trend significantly dwarfed smaller areas of "greening" — a satellite-derived indicator of forest health — during April, May, and June each year from 2000 to 2012, according to research published in Nature
. The browning of Congo's rainforest is significant, researchers said, because most climate models forecast that tropical forests may face increasing stress and rainfall shortages in a warmer and drier 21st century. A continued drying trend might alter the composition and structure of the Congo rainforest, affecting its biodiversity and carbon storage, according to the study. "Recent climate anomalies as a result of climate change and warming of the Atlantic Ocean have created severe droughts in the tropics, causing major impacts on forests," a NASA researcher said.
10 Apr 2014:
Mapping Program Helps
Cities See Money Saved by Planting Trees
New open-source software is helping cities better understand the benefits trees provide by calculating the value of the trees' ecosystem services, such as air quality improvements and CO2 storage. More than a dozen
cities have undertaken tree inventory initiatives, thanks to the OpenTreeMap software
, and residents have helped map more than 1.1 million trees worldwide. In addition to plotting a tree's location, users record its size, species, and other parameters that allow the software to calculate the tree's ecological value in terms of dollars saved through such benefits as cleaner air. San Diego's more than 340,000 mapped trees
, for example, are estimated to provide the city more than $7 million in benefits each year, including $4 million in air quality benefits and $2 million in reduced energy costs. In the coming months, the software will allow city managers to decide where to plant trees for maximum environmental benefit.
On Far-Flung Wrangel Island,
A Scientist Sizes up Muskoxen
As a field biologist for the University of Montana and the Wildlife Conservation Society, Joel Berger has been to his share of end-of-the-earth places. But few have
Muskoxen on Wrangel Island
rivaled Wrangel Island, the rugged, frozen outpost located 300 miles above the Arctic Circle in Russia’s extreme Far East. In the first of three reports for Yale e360
, Berger describes the arduous trip to Wrangel and the scientific work that has taken him there — research with Russian colleagues on the island’s 900 muskoxen, a shaggy beast that is a relic from the Pleistocene era. In subsequent reports, Berger will describe the motley assortment of wildlife that has colonized Wrangel and the contrasting impacts of climate change on eastern Siberia and Arctic Alaska.
08 Apr 2014:
'Living Fences' Dramatically
Cut Livestock and Lion Killings in Tanzania
A novel, low-tech idea is helping Tanzania's lion population rebound: So-called "living fences" — which enclose livestock and are constructed of actively growing trees and chain-link fencing — have cut lion
A Masai villager installs a living fence.
attacks and retaliatory killings by more than 85 percent in the areas they've been installed, the Guardian reports
. Traditionally, the Masai have built livestock enclosures out of thorny acacia trees, but those fences are relatively fragile. Chain-link fencing alone is more durable, but leopards and small lions can scale the fences, and hyenas can tunnel in below. By interweaving actively growing African myrrh trees with the chain link fencing, the Masai have created a barrier that lions can't climb over, and their root systems prevent predators from digging under the fence. Because livestock predation has been cut, communities that had been killing six or seven lions annually now kill, on average, less than one, leading to a rebound in lion populations.
A Personal Note on Peter Matthiessen,
Who Wrote Eloquently of the Natural World
For an editor, the prospect of working with Peter Matthiessen was intimidating. He was one of our finest writers, and he wrote with such poetic precision and lyrical grace that at first it felt presumptuous to propose
any changes to his writing at all. That feeling was heightened by his strong physical presence — an odd mix of Manhattan patrician, rugged outdoorsman, and Zen priest (all of which he was). And yet when I worked as his editor on several magazine articles in the 1990s, it was an immensely satisfying experience. He listened Zen-like, carefully considering all my editing suggestions (with him, they were suggestions
only), and to my delight, accepted almost all of them. Matthiessen died on April 5 at the age of 86, near the Long Island waters he so loved to fish. Read more of e360 editor Roger Cohn’s appreciation of Matthiessen.
E360 Announces Contest
Yale Environment 360
For Best Environmental Videos
is holding a contest to honor the best environmental videos. Entries must be videos that focus on an environmental issue or theme, have not been widely viewed online, and are a maximum of 15 minutes in length. The first-place winner will receive $2,000, and two runners-up will each receive $500. The winning entries will be posted on Yale Environment 360
. The deadline for entries is June 6, 2014. Read further contest information.
03 Apr 2014:
Deforestation of Sandy Soils
Increases the Release of CO2, Study Finds
The texture of the soil that microbes live in determines how much carbon they release after deforestation, with sandy soils sending the most carbon into the atmosphere, according to research
led by Yale scientists.
Soils most affected by forest loss in red; least in yellow.
Subterranean microbes regulate carbon emissions from soil, and drastic changes to the microbial community, such as those that follow deforestation, can allow more CO2 to escape into the atmosphere and exacerbate global warming. The texture of soil, rather than such factors as temperature or nutrient concentrations, was the most important factor governing the release of CO2, the researchers found. Muddy, clay-like soils provide the most stable environment for microbial communities, likely because they're better at retaining nutrients than loose, sandy soils. The team used the findings to map areas in the U.S. where soil microbial communities would be most and least affected by deforestation, which could help inform land management practices.
25 Mar 2014:
Consumer Products Giants
Commit to Deforestation-Free Palm Oil
Two major consumer products companies — General Mills and Colgate-Palmolive — have committed
to using palm oil in their products that does not come from lands cleared from tropical forests, adding to the wave
of corporations that have pledged measures to protect southeast Asian rainforests. The consumer giants' new policies go beyond standards set by the industry's main certification body and include provisions to protect wildlife-rich rainforests, carbon-dense peatlands, and the rights of local communities. Environmental groups are welcoming the commitments, though some believe the companies' pledges should go further. The Union of Concerned Scientists questions General Mills' definition of "high carbon stock" forests, while Greenpeace is urging Colgate-Palmolive to move implementation up to 2015 from 2020. Environmental groups are hopeful that new commitments will pressure Proctor & Gamble, the last remaining consumer products giant without a similar pledge, to adopt deforestation-free palm oil policies.
19 Mar 2014:
CO2 Levels Have Crossed
400 ppm Threshold Far Earlier This Year
Concentrations of carbon dioxide in the atmosphere have reached the 400 parts per million threshold two months earlier this year than last, an indication that the planet will soon experience the 400 ppm level year-round, according to
scientists from the Scripps Institute of Oceanography. Last year was the first time in hundreds of thousands of years that the 400 ppm threshold was crossed. Scripps scientists expect
CO2 levels to hover around 400 ppm for the next two months, when the Northern Hemisphere spring will go into full bloom and plants will suck CO2 from the atmosphere until going dormant in the fall. "It’s just a matter of time before it stays over 400 forever," said Ralph Keeling, who took over the CO2 monitoring program from his father, Charles David Keeling, who started it in 1958. Since then, atmospheric CO2 levels have risen steadily from 313 ppm as the world continues to burn fossil fuels. Scientists estimate it's been 800,000 to 15 million years since the planet has seen concentrations this high.
18 Mar 2014:
Wildflower Season in Rockies
Is 35 Days Longer as Climate Warms
A warming climate has extended the wildflower season in the Rocky Mountains by 35 days since the 1970s,
according to a 39-year study of more than two million blooms. The bloom season, which used to run from late May to early September, now lasts from late April to late
Crested Butte, Colorado
September, the researchers say. Previous, less extensive studies seemed to indicate most wildflowers simply shift their bloom cycles to earlier in the year, but new findings
published in the Proceedings of the National Academy of Sciences
show that the changes are more complex, with the flowers reaching peak bloom sooner and flowering later in the year. The shift in the timing of blooms could have a major impact on pollinating insects and migratory birds. For example, hummingbirds that summer in the Rocky Mountains time their nesting so that their eggs hatch at peak bloom, when there is plenty of flower nectar for hungry chicks. As the bloom season lengthens, the plants are not producing more flowers. The same number of blooms is spread out over more days, so at peak bloom there may be fewer flowers and less food for hummingbirds, the researchers say.
An e360 Interview with Wendell Berry:
Strong Voice for Local Farms and the Land
Author Wendell Berry wrote about and practiced “sustainable agriculture” long before the term was widely used. His early writings in the 1970s, in which he argued against industrial agriculture and for small-scale, local-based farming, strongly influenced the U.S.
© Counterpoint Press
environmental movement. At age 79, Berry still speaks eloquently about the importance of local communities and of caring for the land, while warning about the destructive potential of industrialization and technology. In an interview with Yale Environment 360
, he talked about his Kentucky farm and why he has remained there, why sustainable agriculture faces an uphill battle, and why strong rural communities are important. “A deep familiarity between a local community and a local landscape is a dear thing, just in human terms,” Berry said. “It’s also, down the line, money in the bank, because it helps you to preserve the working capital of the place.”
Read the interview.
03 Mar 2014:
Harsh Winter Causing Large
Die-off of Invasive Insects, Researchers Say
As a frigid winter takes a toll on the United States and Canada, invasive insect populations are also taking a hit. The U.S. Forest Service estimates that up to 80 percent
of emerald ash borers, which have been decimating ash tree populations, were killed by long
Emerald ash borer
stretches of bitter cold in the the upper Midwest this year. Several other insect pests, many of which have migrated northward because of milder winters in recent years, also are faring poorly this winter, including corn earworms and gypsy moths. Researchers remain skeptical, however, that the die-offs will have lasting effects on pest populations. Emerald ash borers in Chicago, for example, survived the sub-zero weather because Chicago temperatures fell only to -17 degrees F, rather than Minnesota's -20 degrees F, which seems to be a critical temperature threshold for the pests.
27 Feb 2014:
Pine Forest Aerosols Play
Significant Role in Climate, Study Says
Pine forest vapors form small aerosol particles that may significantly cool the climate by reflecting the sun's energy back into space, according to new findings
. Scientists have known for decades that gases from pine
Hyytiälä pine forest in Finland
trees can form particles that grow from just 1 nanometer in diameter to 100 nanometers in about a day. The new research, published in Nature
, shows the rapid growth of these particles relies on a chemical chain reaction among pine-scented molecules and atmospheric ozone and oxygen. The growing particle then grabs others like it, eventually snowballing into a 100-nanometer particle — one that's large enough to condense water vapor, prompt cloud formation, and, ultimately, influence climate. Boreal or pine forests give off the largest amount of these compounds, so the finding is especially relevant for the northern parts of North America, Europe, and Russia. But other types of forests emit similar vapors, and the scientists think these may undergo similar rapid chemical reactions.
20 Feb 2014:
Global Forest Watch Tool
Allows 'Near-Real Time' Forest Monitoring
A new online tool
called Global Forest Watch employs a trove of high-resolution NASA satellite imagery and large amounts of computing power to help governments, conservation organizations, and concerned citizens monitor deforestation in "near-real
time." Organized by the World Resources Institute (WRI), Global Forest Watch
uses satellite data to track changes in forest cover since 2000. It's the first tool with the capability of monitoring forests on a monthly basis, potentially allowing groups to take action against deforestation while it's in progress. Businesses committed to eliminating deforestation from supply chains can also use the tool to verify that vendors are not engaging in practices that harm forests. A custom alert feature can also notify a user when there are signs of deforestation in a region the user has selected. "Businesses, governments and communities desperately want better information about forests," said WRI president Andrew Steer. "Now, they have it."
18 Feb 2014:
Website Allows Whistleblowers
To Report Wildlife and Forest Crimes
A new whistleblower site
offers people a secure and anonymous way to report incidents of poaching, wildlife trafficking, and illegal logging around the world. The site is called WildLeaks, a nod to the well-known WikiLeaks site, and it's backed by the California-based Elephant Action League. Users can upload documents, video, or images detailing the crimes, and submissions will be encrypted so data and identities remain secure. The aim
is to provide a safe way for citizens to report these illegal activities so that local and federal governments can take action. Prosecuting wildlife crimes and illegal logging is often a low priority in countries where some of the worst offenses occur; moreover, local government corruption often deters people from reporting such crimes, organizers say. "We [will] work to transform this information into a verified and actionable item, a point for launching an investigation or sharing it with the media or, when possible, with selected and trusted law enforcement officers, always aiming at exposing wildlife crimes and bringing the responsible individuals to justice," said the WildLeaks project leader.
13 Feb 2014:
Australian Bushfire Has Grown
To Size of Melbourne, NASA Image Shows
A fire rivaling the size of the city of Melbourne is raging in southeastern Australia, as a NASA satellite image taken at night earlier this week shows. The Snowy River Complex Fire
, which is burning mountain forests near a
remote national park, is one of three bushfires that flared up last weekend. Fueled by strong winds combined with a heat wave and prolonged dry conditions, the three fires have consumed more than 180,000 hectares (695 square miles), about 100,000 (390 square miles) of which burned in the Snowy River Complex. That fire's dense, opaque smoke is visible from space during night and day, and satellite images show the smoke plume stretching across the Tasman Sea to New Zealand. The Snowy River blaze includes fires that ignited on February 9, as well as fires that were started by lightning in January. Though stunningly large in this view, they do not pose much of a threat to people or infrastructure.
07 Feb 2014:
Documented in Remote Forest in Congo
Researchers have documented a huge population of chimpanzees in the Democratic Republic of Congo — a community of perhaps tens of thousands of individuals with its own unique customs and behaviors, the Guardian reports
. The so-called "mega-culture," which spans 50,000 square kilometers of virtually untouched
Chimps are thriving in a remote Congo forest.
forest, is thought to be the largest population of chimps in Africa and one of the last remaining continuous populations of chimpanzees in the wild, the scientists report
in the journal Biological Conservation
. The researchers first reported on this community in 2007, but their new survey includes detailed videos of the thriving population and its unique behaviors, which include feasting on leopards, using tools to harvest giant African snails and swarming insects, and building ground nests far more frequently than other chimps. While the find is heartening in terms of chimpanzee conservation, the researchers and wildlife advocates fear the population could be decimated by habitat loss and poachers, who stand to make huge profits in the bushmeat trade.
06 Feb 2014:
Maps Show Tropical Corridors
Important to Wildlife As Climate Changes
A new set of maps
highlights the importance of habitat corridors in helping wildlife deal with the effects of climate change and deforestation. The series of maps shows more than 16,000 habitat corridors
— swaths of
land that connect forests or protected areas and allow animals to move between them — in tropical regions of Africa, Southeast Asia, and South America. High-resolution data on biodiversity, endemism, and vegetation density allowed the researchers, led by Patrick Jantz of the Woods Hole Research Center, to determine which corridors are most important for maintaining biodiversity under changing climate conditions. The maps also highlight which corridors are most important for sequestering carbon and averting carbon emissions associated with deforestation. Researchers hope the findings will help guide wildlife protection plans and serve as a framework prioritizing the conservation of habitat corridors.
05 Feb 2014:
Vast Forests and Frequent
Fires Were Key Causes of Ancient Warming
The release of volatile organic compounds from forests and smoke from wildfires had a far greater impact on global warming 3 million years ago than ancient atmospheric levels of carbon dioxide, a new study finds
. During the mid-Pliocene epoch, forests covered a much larger percentage of the planet, releasing large amounts of volatile organic compounds, according to Nadine Unger of the Yale School of Forestry & Environmental Studies. Those compounds are precursors to ozone and organic aerosols, which are both potent greenhouse gases. The dark foliage of the planet's abundant forests also absorbed large amounts of solar energy, another reason why the Pliocene was a relatively warm era even though atmospheric levels of CO2 were not exceptionally high. The research — based on earth-system modeling that used a supercomputer capable of processing 52 trillion calculations per second — provides evidence that dynamic atmospheric chemistry played an important role in past warm climates, underscoring the complexity of climate change, the authors write in Geophysical Research Letters
18 Dec 2013:
Mapping Course and Software
Make Forest Monitoring Widely Accessible
Citizen scientists interested in tracking the health of the planet's forests have a new tool at their disposal. New software that uses satellite technology to map and
monitor changes in forested areas is being made available to the public
through a free online course. Users who complete the course, hosted by Stanford University
, can receive a license to operate the software, called CLASlite. CLASlite, or the Carnegie Landsat Analysis System lite, is a highly automated system for converting satellite imagery from its original, raw format into maps that can be used to detect deforestation, logging, and other disruptions. It was developed by Carnegie researcher Greg Asner to help governments, nongovernmental organizations, and academic institutions conduct high-resolution mapping and monitoring of forests
. "We are making the science of forest monitoring broadly available to people who want and need to participate in tracking and managing the health of their forests," said Asner.
29 Nov 2013:
Wide Mangrove Destruction
Is Documented Along Coast of Myanmar
Rapid agricultural expansion destroyed nearly two-thirds of the mangrove forests
in Myanmar’s Ayeyarwady Delta between 1978 and 2011, increasing the region’s vulnerability to cyclones and typhoons, according to a new study. Using remote sensing imagery
and field data, researchers from Myanmar and Singapore said that the dense mangrove cover in the Ayeyarwady Delta declined from 2,623 square kilometers to 1,000 square kilometers in that 33-year period. The main cause was agriculture expansion and the researchers said that if rates of destruction continue at their current pace the delta’s mangroves could be completely deforested by 2026. Reporting in the journal Global Environmental Change
, the scientists said the loss of mangroves in the Ayeyarwady Delta could put the region at greater risk of major storms such as Cyclone Nargis, which killed 138,000 people in Myanmar in 2008. But the researchers said the destruction could be slowed if Myanmar creates coastal protected areas.
26 Nov 2013:
Updated Conservation List
Finds Forest Giraffes on Brink of Extinction
In an updated list released today, the International Union for the Conservation of Nature (IUCN) noted some significant successes and failures in global wildlife
Okapi, or forest giraffe
conservation efforts. A major success story is the leatherback sea turtle
, whose Atlantic population has recovered enough for the species to be considered only vulnerable, rather than critically endangered. The IUCN attributed the leatherback rebound to better protection of nesting beaches and reduced fisheries bycatch. The updated Red List contains more somber news, though, for the blue-tongued forest giraffe
, the national symbol of the Democratic Republic of the Congo. The striped-legged forest giraffe, a species of okapi, is on the brink of extinction due mainly to the long, ongoing civil war in that country, which has led to increased poaching and loss of habitat. The Red List's ranks of threatened species have grown by 352 species since this summer
, Mongabay reports, with roughly 21,000 species now listed as threatened.
15 Nov 2013:
Groundbreaking Mapping Project
Depicts Forest Change Around the Globe
Scientists from Google, U.S. universities, and federal agencies have for the first time produced a high-resolution global map showing in striking detail the extent of deforestation across the globe.
The project — which relied heavily on expertise from the computing
center Google Earth Engine — documents a loss of 888,000 square miles of forest between 2000 and 2012, along with a gain of 309,000 square miles of new forest. The rate of deforestation is equal to losing 68,000 soccer fields of forest every day for the past 13 years, or 50 soccer fields every minute, says the World Resources Institute
. Brazil, once responsible for a majority of the world's tropical forest loss, is now the global leader in scaling back forest destruction, cutting its deforestation rate in half over the past decade, researchers report in Science
. Over the same period, Indonesia has more than doubled its annual rate of forest loss, despite a supposed 2011 Indonesian government moratorium on new logging licenses.
06 Nov 2013:
Disturbed Tropical Forests
Are Slow to Regain Plant Biodiversity
In tropical forests that are regrowing after major disturbances, the ability to store carbon recovers more quickly than plant biodiversity, researchers from the U.K. have found
. However, even after 80 years, recovering forests store less carbon than old-growth
A regrowing tropical forest in Brazil
forests, according to a study published in the Proceedings of the Royal Society B.
This is likely because regenerating forests are often dominated by small, fast-growing trees and it may take centuries for larger trees, which hold more carbon, to become established, according to scientists from the Center for Ecology & Hydrology and Bournemouth University, who studied more than 600 recovering tropical forests. Tree species that are hallmarks of old-growth forests were rare or missing in the regrowing forests, the study showed. Since regenerating forests are often located far from old-growth forests and surrounded by farmland, it may be difficult for animals to move seeds between the forests, which may account for the lower plant biodiversity, researchers said.
22 Oct 2013:
Southern Amazon Rainforest
In Danger as Dry Season Expands, Study Says
The dry season in the southern part of the Amazon rainforest is lasting three weeks longer than it did 30 years ago, putting the forest at higher risk for fires and tree mortality, according to new research from the University of Texas
. The most likely culprit is global
warming, says lead researcher Rong Fu. Even if future wet seasons become wetter, rainforest soil can only hold so much water, Fu explained. That water must sustain the forest throughout the entire dry season, and as the dry season lengthens the rainforest becomes increasingly stressed, vegetation growth slows, and the risk of fire rises. During a severe drought in 2005, the Amazon actually released a large amount of carbon dioxide into the atmosphere, rather than acting as a net carbon sink. Should dry seasons continue to expand, conditions like those in 2005 could become the norm, accelerating the buildup of CO2 in the atmosphere, the researchers wrote in the Proceedings of the National Academy of Sciences
11 Oct 2013:
Agricultural Ammonia Emissions
Threatening U.S. National Parks, Study Finds
Ammonia emissions from agricultural fertilizers are threatening sensitive ecosystems in U.S. national parks, a study led by Harvard researchers
has found. Thirty-eight national parks are seeing nitrogen deposition levels at or above the threshold for ecological damage,
Great Smoky Mountains N.P.
the study says. In natural ecosystems, excess nitrogen can disrupt nutrient cycling in soil
, cause algal overgrowth, and make aquatic environments acidic. While some of that nitrogen comes in the form of nitrogen oxides (NOx) from power plants and vehicle exhaust, existing air quality regulations and new clean energy technologies are helping reduce NOx emissions. Ammonia emissions from agricultural operations, however, are expected to climb as demand for food and biofuels surges. Daniel Jacob, who led the study, said that because ammonia is volatile, only 10 percent of the nitrogen makes it into the food, with much of it escaping through the atmosphere and being deposited across the landscape. According to the report, published in Atmospheric Chemistry and Physics
, hardwood trees, such as those shown above, are most sensitive to excess nitrogen in eastern temperate forests, while in western national parks lichens appear to suffer first.
08 Oct 2013:
Eighty Percent of Ecosystems
Vulnerable to Climate Change, Study Finds
Climate change could significantly transform up to 86 percent of the planet's land ecosystems under worst-case global warming scenarios, according to researchers at Germany's Potsdam Institute for Climate Impact Research
. That estimate is based on a 4 to 5 degree C temperature increase by the year 2100 — a scenario that is plausible given many nations' reluctance to enact greenhouse gas emissions limits, the researchers say. Even if global temperatures are kept to 2 degrees C above preindustrial levels, 20 percent of natural land ecosystems are at risk of moderate or major changes, especially high-altitude and high-latitude regions. Such changes could include boreal forests being transformed into temperate savannas, trees growing in thawed Arctic tundra, or even a dieback of some of the world's tropical forests. "Essentially, we would be leaving the world as we know it," says Sebastian Ostberg, who led the research. "The findings clearly demonstrate that there is a large difference in the risk of global ecosystem change under a scenario of no climate change mitigation compared to one of ambitious mitigation," he added.