Yahoo News 10 Sep 09;
CHICAGO (AFP) – Polar bear cubs, the arctic fox and caribou herds are among the victims of dramatic changes in the Arctic due to climate change, a study published Thursday found.
"Species on land and at sea are suffering adverse consequences of human behavior at latitudes thousands of miles away," said lead author and biologist Eric Post of Penn State University.
"It seems no matter where you look -- on the ground, in the air, or in the water -- we're seeing signs of rapid change."
The study published in the journal Science reviewed recent ecosystem-wide studies of the biological responses to Arctic warming.
They found the effects of a one-degree Celsius warming over the past 150 years were dramatic and cautioned that it is difficult to predict the consequences of an expected six-degree warming over the next century.
"The Arctic as we know it may soon be a thing of the past," Post said.
Sea ice cover has shrunk by a staggering 45,000 kilometers a year over the past 20 to 30 years, causing a rapid decline in the gulls, walruses, seals, horned narwhal whales and polar bears which rely upon it.
Snow cover on land also has declined and is melting faster.
Polar bears and ringed seals -- already in danger of extinction -- are losing cubs when early spring rains collapse the lairs they build under the snow.
Arctic fox populations are down as red foxes move north.
Fewer caribou calves are surviving because their mothers have been unable to adjust the calving season to changes in plant growth and are not getting enough to eat. Warmer summers also have increased the number of insects and parasites which prey on the migratory animals.
Moths are moving north and affecting the dynamics of trace gas exchange by defoliating mountain birch forests and low Arctic trees and shrubs.
That could have a significant impact on the Arctic's ability to act as a carbon sink, Post warned, noting that one study found an unexpectedly large release of methane in Greenland at the onset of autumn soil freezing.
Warming temperatures are allowing shrubs and trees to expand their range and also are damaging native vegetation.
One winter warming episode led to vegetation damage so extensive that plant product was cut by 26 percent over an area of at least 1,400 square kilometers.
"There is little functional redundancy among species in Arctic ecosystems," Post said.
"Therefore, relatively small shifts in species ranges or abundances may cause fundamental changes in a unique ecosystem that also is important for tourism and traditional cultures."
Effects of Arctic warming seen as widespread
Randolph E. Schmid, Associated Press Yahoo News 10 Sep 09;
WASHINGTON – Arctic warming is affecting plants, birds, animals and insects as ice melts and the growing season changes, scientists report in a new review of the many impacts climate change is having on the far north.
As the global climate changes, the Arctic Circle has been warming faster than other regions and scientists have documented a series of affects on wildlife in the region.
Indeed, just last week researchers reported that the Arctic is warmer than it's been in 2,000 years, even though it should be cooling because of changes in the Earth's orbit that cause the region to get less direct sunlight.
"The Arctic as we know it may soon be a thing of the past," Eric Post, an associate professor of biology at Penn State University, said in a statement.
Post led a research team that studied the Arctic during the International Polar Year, which ended in 2008. Their findings are reported in Friday's edition of the journal Science.
Snow cover has declined steadily in recent years and in the last two to three decades the minimum sea ice coverage declined sharply, a change that affect animals like polar bears that depend on the ice for habitat and hunting.
"Species on land and at sea are suffering adverse consequences of human behavior at latitudes thousands of miles away," Post said. "It seems no matter where you look — on the ground, in the air, or in the water — we're seeing signs of rapid change."
In addition, he added, the Arctic is very complex and "not all populations within a given species respond similarly to warming because physical and landscape features that interact with climate can vary tremendously from site to site."
For example, migratory caribou in Greenland and elsewhere are declining, the researchers said, since the animals have not been able to adjust their calving season to keep it synchronized with changes in plant growth.
As a result, the time when the females need the most food no longer matches the time when the most food is available, and fewer calves survive. In addition, warmer weather can produce more insects and parasites to prey on the caribou.
On the other hand, wild reindeer on the Norwegian islands of Svalbard appear to have benefited from the earlier seasonal loss of snow cover. These animals don't migrate and the longer growing season and less snow cover means more food for them.
The researchers found that with warmer conditions red foxes are moving north, displacing Arctic foxes from their territories.
Also expanding their territories to the north are the winter moth, which defoliates mountain birch forests, and species of Arctic trees and shrubs.
Having more shrubs can provide food for reindeer and musk oxen grazing, and their trampling and defecation encourages the growth of grasses, which in turn attract geese.
And, as if to help prove the case, the U.S. Geological Survey reported separately that the Pacific brant, a small sea goose, has shifted northward from areas such as Mexico to sub-Arctic areas as Alaska's climate has warmed over the last four decades.
Before 1977 only about 3,000 brant were detected wintering in Alaska, while now that has jumped to as many as 40,000 birds.
The changing Arctic climate appears related to changes in the availability and abundance of eelgrass, the primary food of brant in their nonbreeding season, survey researchers said.
Post's research was funded by Aarhus University in Denmark, the Danish Polar Center and the U.S. National Science Foundation. In addition to the U.S. Geological Survey, funding for its study came from the Izembek National Wildlife Refuge, U.S. Fish and Wildlife Service.
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On the Net:
Science: http://www.sciencemag.org
The Climate's Warm Future Is Now in the Arctic
A new survey reveals just how far and how fast global warming is altering the Arctic
David Biello, Scientific American 10 Sep 09;
When the summer sea ice goes, the Arctic will lose the ivory gull, Pacific walrus, ringed seal, hooded seal, narwhal and polar bear—all animals that rely on the ice for foraging, reproduction or as refuge from predators. And the sea ice is going, faster and faster: In the past 30 years, minimum sea ice cover in the Arctic Ocean has declined by 45,000 square kilometers annually*—an area twice the size of New Jersey is lost each year.
"Sea ice is like rainforest in the tropics. There are species that can't live without it," says ecologist Eric Post of The Pennsylvania State University, lead author of a paper in the September 11 Science that lays out a broad review of climate change's impact on the Arctic. "It's melting earlier, freezing up later, the contiguous extent is diminishing, and it's happening faster than anyone expected it to happen 10 years ago."
As a wrap-up of ecological studies conducted during the Fourth International Polar Year, Post and a slew of colleagues surveyed the state of the Arctic and found it to be not good, thanks to climate change. "We looked at plants and animals: vascular and nonvascular plants, migratory and nonmigratory animals, vertebrates and invertebrates, saltwater and freshwater, on the land or in the air—everything is changing," Post says. "It doesn't really matter where you look in the Arctic. Things are changing fast."
Rapid change is coming even for animals once thought to be relatively immune, such as caribou. Whereas the nonmigratory population of the animals on the Norwegian Svalbard Islands is burgeoning thanks to more winter snowmelt exposing a greater abundance of plant life for foraging, caribou in other parts of the Arctic are suffering. In spring, plants are blooming earlier in the year thanks to warmer early spring temperatures, but caribou are still calving at the same time, meaning calves are born after most of the food is available, and therefore fewer of them survive.
"I had no idea caribou could be on the brink of collapse. They seemed to have all the right traits to adapt," Post says. "Now they're of critical concern."
Particularly to the peoples of the Arctic who, in many cases, rely on hunting caribou or other animals to survive. "If you talk to the Inuit people in Greenland, they are suffering consequences for something they haven't contributed to themselves," Post notes. "We're taking away elements of a lifestyle that has worked for them for thousands of years. If somebody was doing that to us, don't you think we'd be upset?"
But the list of effects do not stop with the loss of a way of life and sea ice or the mismatch between spring blooms and caribou birthing: red foxes are replacing Arctic foxes farther and farther north; snow cover is diminishing; early spring rains now wash away seal dens, exposing pups; unusually warm periods in winter kill off Arctic plants and they do not rebound the following summer; and lemming and vole populations have crashed and remained at low levels for nearly a decade without recovering, among others. "There's been such a decline in snow cover that it affects [rodent] survival," Post says. "It means that species like snowy owls and Arctic foxes that are dependent on finding rodents will also suffer."
This is all happening with an increasing temperature of just one degree Celsius over the past century. In the next 100 years, the Arctic might warm as much as 6 degrees Celsius according to the United Nations Intergovernmental Panel on Climate Change. "If it were to get to three degrees [Celsius] warmer on average, the Arctic would be a thing of the past," Post says. "Polar bears, long winters of snow, sea ice cover—it wouldn't be the case anymore."
Instead the Arctic might become more like the boreal forests of Alaska, Canada, Scandinavia and Siberia—vast stands of spruce trees that do not support the unique Arctic flora and fauna.
The problem confronting Arctic species is not the warming itself, of course; there have been similar episodes in Earth's history, such as the warming during the transition from the Pleistocene to the Holocene epochs. It is the speed with which the greenhouse gases from fossil fuel burning are warming the globe. "The rate of change is so fast now," Post says. "It's about whether it's getting warmer over several decades or one decade. For a long-lived species there's no chance to keep up, no chance for evolution to keep up."
For his part, Post is hoping that the world will begin to treat Arctic biodiversity as worthy of conservation, more like tropical biodiversity, for example. After all, the Arctic is actually abundant with unique species and ecosystems, not a lifeless, white wasteland.
Post's report is not all bad news: Arctic warming has begun to promote the spread of trees and shrubs farther north, and the growth of these plants can lock up more carbon dioxide as they flourish.
Unfortunately, the warmth is also permitting the northward march of insect pests like the winter moth, which defoliates trees and shrubs and reduces the overall carbon sequestration. Plus, the advance of shrubs is affecting ecosystems, promoting more microbial activity in the soil and, ultimately, the release of methane—another greenhouse gas that traps 25 times as much heat as carbon dioxide over 100 years in the atmosphere.
In other words, warmth—and big changes for the Arctic—will keep coming. "Even if we restrict carbon emissions, it will get warmer," Post says, thanks to the greenhouse gases already in the atmosphere and feedback effects like the loss of sunlight-reflecting sea ice and snow cover. "That doesn't mean we shouldn't curb emissions. It's a matter of damage control.... We might be losing the Arctic as we know it but we need to do everything we can to make sure the problem doesn't spread."
The Changing Arctic: How Animals Respond to Climate Change
Andrea Thompson, livescience.com Yahoo News 10 Sep 09;
The dramatic changes sweeping the Arctic as a result of global warming aren't just confined to melting sea ice and polar bears - a new study finds that the forces of climate change are propagating throughout the frigid north, producing different effects in each ecosystem with the upshot that the face of the Arctic may be forever altered.
"The Arctic as we know it may be a thing of the past," said Eric Post of Penn State, who led an international team that brought together research on the effects of climate change from ecosystems across the Arctic.
The study, detailed in the Sept. 11 issue of the journal Science, is one of the first to knit together and bring light to the details of the multitude of changes from across the region.
"Usually, when people talk about declines in the Arctic, they show a figure with declining sea ice extent and then show a picture of a polar bear. This study tries to move beyond such recourse by citing the wide array of papers that quantify ecological decline in the Arctic," said Ken Caldeira of Stanford University, who was not involved in the study. "I know of no similar paper that brings together such a wealth of scholarship on the state of Arctic ecosystems."
Arctic amplification
While the Earth on average has warmed by about 0.7 degrees Fahrenheit (0.4 degrees Celsius) over the past 150 years, the Arctic has warmed by two to three times that amount.
This amplification of the global warming signal in the Arctic is partly the result of a self-feeding cycle: As sea ice melts, the oceans absorb more heat from the sun's rays, causing less ice to re-form come winter.
In the last two to three decades alone, the amount of ice covering the Arctic at the summer minimum has declined by about 17,000 square miles (45,000 square kilometers, or about the size of Vermont and New Hampshire combined) a year, the researchers say, in addition to breaking up earlier in the season and freezing back later.
Snow cover over land has also decreased in the northernmost latitudes, as well as melting earlier come spring.
These physical changes to the environment are having a profound impact on the flora and fauna that dwell in the Arctic.
"Species on land and at sea are suffering adverse consequences of human behavior at latitudes thousands of miles away," Post said. "It seems that no matter where you look - on the ground, in the air or in the water - we're seeing signs of rapid change."
Ice melt and migrations
Arctic species that are dependent on the stability and persistence of the ice sheet - of which the polar bear is the most widely-recognized example - are particularly feeling the brunt of climate change. The loss of sea ice is causing a rapid decline in the number of ivory gulls, Pacific walrus, ringed seals, hooded seals, narwhals, and of course, polar bears.
Polar bears and ringed seals both give birth in lairs or caves under the snow. If these refuges collapse in unusually early spring rains, the newborn pups end up lying exposed on the ice, where they die from hypothermia or predation.
Other species are being threatened by the northward migrations of species once confined to more hospitable lower latitudes. One of the most visible invaders is the red fox, which is displacing the native Arctic fox.
The winter moth, which defoliates mountain birch forests, has also been marching poleward, as have Low Arctic trees and shrubs, which affect the dynamics of an ecosystem. Adding more shrubs and trees to the landscape promotes deeper snow accumulation, which increases winter soil temperatures. Warmer soils mean more microbial activity, which makes the habitat even more suitable for shrubs.
The addition of shrubs also propagates changes throughout the ecosystem and affects the ability of the tundra (or frozen soil) to store carbon: While more shrubs may lengthen the period of the growing season when the soil acts as a carbon sink, it also provides more food for grazing musk oxen and reindeer, who limit the carbon-soaking ability as they trim the plants. Grazing, trampling and defecation by herbivores also promote the growth and spread of grasses, which attract geese. Geese, in turn, can influence the productivity of lakes where they rest and graze.
Good for me, bad for you
The changes in Arctic ecosystems can have opposing impacts on different species, with some even benefiting from them.
The study found that wild reindeer on the Norwegian archipelago of Svalbard benefit from earlier snow melt. With less snow on the ground and a longer growing season, the nonmigratory reindeer can take advantage of an explosion in plant abundance. The result is more reindeer, as they are more able to reproduce and less likely to die.
On the losing side of the equation are migratory caribou in Low Arctic Greenland, whose numbers the researchers find are declining. The caribou haven't been able to adjust their calving season to keep in step with the change in plant season, so new mothers in need of more food have less available and more calves die. Hotter summers may also bring more insects and parasites to prey on the caribou.
The reduction in caribou numbers in turn impacts the local indigenous human populations: "Inuit hunters at my study site in Greenland have all but given up on hunting caribou there," Post said.
Forecasting the future
Understanding why some ecosystems benefit or are less impacted by climate change while others are on the brink of collapse is one area that the researchers say needs more attention.
Documenting the changes in this region is also key to developing any conservation plans, particularly because there are relatively few species in the Arctic.
"There is little functional redundancy among species in Arctic ecosystems," Post said. "Therefore, relatively small shifts in species ranges or abundances may cause fundamental changes in a unique ecosystem that also is important for tourism and traditional cultures."
The rapid changes in the Arctic also provide a way for scientists to tackle a long-standing problem in climate research, predicting what will happen to ecosystems in a warming world, Caldeira said. While some predictions, such dipping polar bear numbers from sea ice melt, are more predictable, others, such as the dynamics between shrub growth and grazing, are harder to predict.
"The Arctic is, unfortunately, a good early laboratory in which to test our predictions of ecosystem response to global change," Caldeira told LiveScience.
To better understand the changes taking place in the Arctic - and the Earth as a whole - the team proposes a series of studies across the region to monitor the drivers of climate change and the biological responses to them over the long term.
"We've seen a great deal of emphasis recently on the melting of Arctic ice," Post said. "The broad, rapid, and in some cases devastating changes documented in this paper remind us of why it's important to give consideration to the consequences of rising temperatures."
The study was supported by Aarhus University, The Danish Polar Center and the U.S. National Science Foundation.
Dramatic Biological Responses To Global Warming In The Arctic
ScienceDaily 10 Sep 09;
"The Arctic as we know it may soon be a thing of the past," says Eric Post, associate professor of biology at Penn State University. Post leads a large, international team that carried out ecosystem-wide studies of the biological response to Arctic warming during the fourth International Polar Year, which ended in 2008. The team's results will be reported on 11 September 2009 in the journal Science.
The team's research documents a wide range of responses by plants, birds, animals, insects, and humans to the warming trend. The scientists found that the increase in mean annual surface temperature in the Arctic over the last 150 years has had dramatic effects. In the last 20 to 30 years, for example, the seasonal minimal sea ice coverage has declined by a staggering 45,000 square kilometers per year. Similarly, the extent of terrestrial snow cover has declined steadily, with earlier melting and breaking up and an earlier start to the growing season.
"Species on land and at sea are suffering adverse consequences of human behavior at latitudes thousands of miles away," declares Post. "It seems no matter where you look -- on the ground, in the air, or in the water -- we're seeing signs of rapid change."
The study led by Post shows that many iconic Arctic species that are dependent upon the stability and persistence of sea ice are faring especially badly. Loss of polar ice habitat is causing a rapid decline in the numbers of ivory gull, Pacific walrus, ringed seal, hooded seal, narwhal, and polar bear. The researchers found that Polar bears and ringed seals, both of which give birth in lairs or caves under the snow, lose many newborn pups when the lairs collapse in unusually early spring rains. These species may be headed for extinction.
The research also reveals that species once confined to more southerly ranges now are moving northward. Among the most visible invaders are red foxes, which are displacing Arctic foxes from territories once too cold for red foxes. Some of the less showy invaders that the scientists found also are moving northward include the winter moth, which defoliates mountain birch forests, and species of Low Arctic trees and shrubs, which affect the dynamics of trace-gas exchange. The presence of more shrubs and trees promotes deeper snow accumulation, increasing soil temperatures during the winter, and more microbial activity in the soil, which in turn makes the habitats more suitable for shrubs. Increasing the shrub cover may lengthen the period during the plant growing season when the tundra acts as a carbon-dioxide sink.
Countering this change, the research reveals, are musk oxen and reindeer, which browse on shrubs, limiting their carbon-soaking capacity and northward expansion to the High Arctic. Grazing, trampling, and defecation by these herbivores promote the growth and spread of grasses, which further attract geese. The geese in turn influence the productivity of lakes, where they rest and graze. The research indicates that complex aquatic and marine food webs like these are extremely vulnerable to alteration due to changes in temperature, precipitation, and nutrient load from the land.
The paper by Post's research team shows that the effects of Arctic warming have been dramatic so far, especially since the warming amounts to only about 1-degree Celsius over the last 150 years. Post said it is difficult to predict what will happen with the anticipated 6-degree warming over the next century.
"The results of our studies so far reveal widespread changes, but also a surprising heterogeneity in biological responses to warming," comments Post. For example, the study shows that wild reindeer on the Norwegian archipelago of Svalbard actually have benefited from melting of snow during winter, and perhaps also from the earlier seasonal loss of snow cover. With less snow cover and a longer growing season, these nonmigratory reindeer have taken advantage of the increased plant abundance, with the result that reindeer populations and their ability to reproduce are up, while mortality is down.
In contrast, migratory caribou in Low Arctic Greenland and elsewhere are declining in numbers, the study found. The caribou have not been able to adjust their calving season to keep it synchronized with changes in plant growth. Thus, the research shows, the time when the females need the most food no longer matches the time of maximum food availability, so fewer calves survive. The research suggests that hotter summers may result in more insects and parasites to prey on the caribou, which in turn may reduce the annual caribou harvest by local indigenous peoples. "Inuit hunters at my study site in Greenland have all but given up on hunting caribou there. What will be the next component to disappear from their traditional lifestyle, a lifestyle that has worked for thousands of years?" wonders Post.
Many questions remain unanswered as scientists wrestle with forecasting future events and developing plans to conserve the fragile Arctic ecosystems. Because there are relatively few species in the Arctic, ecosystems in this region may be more vulnerable to changes in its climate. "There is little functional redundancy among species in Arctic ecosystems," explains Post. "Therefore, relatively small shifts in species ranges or abundances may cause fundamental changes in a unique ecosystem that also is important for tourism and traditional cultures."
Why do some parts of the ecosystem appear to be unaffected by rising temperatures, while others seem to be heading for collapse? For example, despite heavy harvest and changing environmental conditions, sockeye salmon production in Bristol Bay, Alaska, has remained relatively stable or even increased over the last century. Though hundreds of salmon populations are scattered throughout a range of habitats, the system somehow has compensated for these serious demands.
It has long been assumed that the most important biological activities in the Arctic occur during the growing season, but the work highlighted by Post's team suggests otherwise. One natural winter warming episode in the sub-Arctic led to vegetation damage so extensive that plant productivity in the following summer was reduced by 26 percent over an area of at least 1400 square kilometers. In a different area, there was an unexpectedly large release of methane into the atmosphere at the onset of autumn soil freezing. Though working in the Arctic in the autumn and winter poses logistical problems, the findings indicate the importance of monitoring the dynamics of the ecosystem year-round.
"People have thought of the Arctic as a relatively simple ecosystem that is easily understood, but in fact it is very complex," explains Post. "Not all populations within a given species respond similarly to warming because physical and landscape features that interact with climate can vary tremendously from site to site. I think response heterogeneity is going to be one of the keys to species persistence, community integrity, and ecosystem function as the Arctic continues to warm."
Post's team calls for establishing a pan-Arctic series of integrated baseline studies to monitor the physical drivers of climate change and the biological responses to them over the long term. "We've seen a great deal of emphasis recently on the melting of Arctic ice," Post says. "The broad, rapid, and in some cases devastating changes documented in this paper remind us of why it's important to give consideration to the consequences of rising temperatures."
In addition to Eric Post at Penn State University, the team he led was comprised of biologists, ecologists, geographers, botanists, anthropologists, and fish and wildlife experts from the University of Alberta and the Canadian Wildlife Service in Canada; Aarhus University and the University of Copenhagen in Denmark; the University of Helsinki in Finland; the Arctic Ecology Research Group in France; the Greenland Institute of Natural Resources in Greenland; the University Centre on Svalbard, the University of Tromsø, and the Centre for Saami Studies in Norway; the University of Aberdeen and the University of Stirling in Scotland; Lund University and the Abisko Scientific Research Station in Sweden; the University of Sheffield in the UK; and the Institute of Arctic Biology and the U.S. Geological Service at the University of Alaska-Fairbanks, the Environment and Natural Resources Institute of the University of Alaska-Anchorage, and the University of Washington in the United States.
Support was provided by Aarhus University, The Danish Polar Center, and the U.S. National Science Foundation.
Journal reference:
1. Eric Post, Mads C. Forchhammer, M. Syndonia Bret-Harte, Terry V. Callaghan, Torben R. Christensen, Bo Elberling, Anthony D. Fox, Olivier Gilg, David S. Hik, Toke T. Høye, Rolf A. Ims, Erik Jeppesen, David R. Klein, Jesper Madsen, A. David McGuire, Søren Rysgaard, Daniel E. Schindler, Ian Stirling, Mikkel P. Tamstorf, Nicholas J.C. Tyler, Rene van der Wal, Jeffrey Welker, Philip A. Wookey, Niels Martin Schmidt, and Peter Aastrup. Ecological Dynamics Across the Arctic Associated with Recent Climate Change. Science,, 11 September 2009: 1355-1358\ DOI: 10.1126/science.1173113
Adapted from materials provided by Penn State.
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