Arctic Denizens Feel The Heat
An upcoming scientific report confirms that climate change already is upsetting wildlife and human communities in the most vulnerable region on the planet
For a preview of how climate change may disrupt the world's people and wildlife, consider the transformations underway in our northernmost state. Over the past few decades, Alaska—along with much of the rest of the Arctic—has been warming more rapidly than any other place on Earth. And according to a soon-to-be-released report, the region should brace itself for even more dramatic change in the future.
The report, scheduled for publication in November, summarizes results of the Arctic Climate Impact Assessment (ACIA), a four-year effort by an international team of more than 500 scientists and other Arctic experts—the first comprehensive analysis of the impact of climate change on this vast territory. Says meteorologist and ACIA chairman Robert Corell, the Arctic's climate already has changed "more rapidly and persistently than at any time since the beginning of civilization."
In two of the most affected areas, Alaska and western Canada, Corell reports that winter temperatures have increased by as much as 3 to 4 degrees C over the past 60 years—compared with an average increase of 0.6 degrees C over the past 100 years throughout the rest of the world. By the end of the 21st century, he says, the Arctic is expected to warm by more than twice the global average.
For some Arctic inhabitants, changes in the area and thickness of sea ice will have a greater impact than temperature itself. According to the assessment, sea ice coverage in the Arctic Ocean has shrunk an average of 10 percent over the past 30 years. Based on several computer models, ACIA participants project further losses—with one model predicting that by the middle of this century the Arctic Ocean will be ice free in summer.
That scenario, which would create a shortcut for ships sailing between the Orient and North America and Europe, will be good news for some, including companies eager to exploit the Arctic's mineral and oil wealth. But for thousands of indigenous communities whose lives depend on the environment, and where climate has been stable for many generations, "both cultures and livelihoods will be challenged," says Corell. Some indigenous groups already are struggling to adapt to climate change (see opposite).
Biologists foresee little good news for wildlife. In terrestrial habitats, vegetation zones are shifting northward as temperature rises, with forests expanding into tundra and tundra into polar deserts. One likely result, notes the report, will be a tundra zone smaller than it's been for 21,000 years, significantly decreasing habitat for breeding birds and grazing mammals. Wildlife, meanwhile, is on the move as well, altering ranges and migration routes in an effort to adapt. The problem, says Corell, is that the changes are not synchronous. As some plants and animals move faster or in different directions than others, they are likely to lose species they depend upon for survival. "Climate change is the most significant threat to wildlife worldwide," says Corell, "and we're going to see it first in the Arctic."
One Arctic species, the polar bear, is already in trouble. For the past three decades, Canadian Wildlife Service scientist Ian Sterling has studied a population along western Hudson Bay, where each summer pregnant and nursing females use sea ice as a base for hunting seals, their primary food. But the ice is melting about two weeks earlier than it did 20 years ago, and Sterling found that bears today weigh less and give birth to fewer cubs than they did when it lasted longer. (See National Wildlife, February/March 2004.)
What makes forecasting the future for bears and other Arctic wildlife difficult—and worrisome—is that global warming is not the only variable. According to University of Alaska–Fairbanks Arctic biologist David Klein, lead author of the assessment's chapter on wildlife conservation, "Climate change is perhaps the major driver of change in the Arctic, but there are other forces, including habitat loss, overfishing and pollution." Scientists have discovered that polar bears, for example, have higher concentrations of mercury in their bodies than any other animals on Earth.
Those of us who inhabit more southerly climes cannot rest easy, either. "What happens in the Arctic over the next decade," says Corell, "is likely to happen throughout the world over the next 25 to 30 years."
Laura Tangley is a senior editor for this magazine. For more information on the ACIA report, see
LIVING ON THE FRONTLINES
At a recent United Nations panel, "Climate Change in the North Country," Gwich'in Indian and NWF board member Faith Gemmill described some of the ways climate change has affected her village, about 110 miles north of the Arctic Circle. Portions of her talk are excerpted here.
Climate change is upsetting the delicate balance in many ecosystems. This affects our people's ability to sustain our subsistence livelihoods. I see the changes now when I walk on our lands. The lakes are dry. These lakes are very important subsistence fishing lakes; they have always provided our people with our springtime fishing, and the fish were delicacies. But now the fish are gone.Plants are growing faster, and we have noticed that when it comes time to pick our berries, they have already dropped. The reason is due to strange weather. Each year it is the same nowadays; we are lucky to get berries at all in the summer.The big glaciers that surround our village are melting, and some exist no more. These glaciers are important places for caribou; they take refuge there from heat and mosquitoes. Where do the caribou go now to rest and find relief?
Climate Change May Decimate Alaskan Tundra ...
Among many troubling forecasts in the upcoming Arctic Climate Impact Assessment (ACIA) is the prediction that Arctic tundra will shrink significantly in the future, eliminating critical feeding and breeding habitat for a variety of wildlife species. At an August meeting of the Ecological Society of America in Seattle, Washington, one researcher bolstered such fears when she presented the results of recent computer modeling.
Dominique Bachelet, an associate professor in Oregon State University's bioengineering department, developed the Dynamic Global Vegetation Model MC1 with colleagues at her school and at the U.S. Forest Service to predict how different climate scenarios might affect vegetation growth, carbon storage, soil processes and other ecological phenomena. Their model suggests that within a century, between 77 and 90 percent of the Alaskan tundra present in 1920 will disappear. A cold, dry habitat characterized by permanently frozen deep soil, an absence of trees and a short growing season for grasses and shrubs, tundra today covers much of the state of Alaska and supports healthy populations of wolves, brown bears, wolverines, caribou, mink, lemmings and other mammals as well as millions of migrating waterfowl.
Unlike many ecosystems, "the tundra has no place to go," said Bachelet, "and it will largely disappear from the Alaskan landscape, along with the related plant, animal and even human ecosystems based upon it."
...and Generate More Earthquakes
During the past century, many Arctic glaciers have gotten smaller or disappeared entirely, and, according to the ACIA and other sources, increasing temperatures and continued shifts in precipitation patterns will accelerate those losses in the future. Now a pair of researchers has discovered what might appear to be an unexpected consequence: more earthquakes in southern Alaska.Jeanne Sauber of NASA's Goddard Space Flight Center and Bruce Molnia of the U.S. Geological Survey already knew that melting glaciers reduces weight on the Earth's crust, allowing tectonic plates—mobile pieces of the crust—to move around more freely. Colliding plates can then cause a build up of pressure that is often relieved by an earthquake.Using a combination of satellite data, computer models and other tools, Sauber and Molnia examined previous Alaskan earthquakes. The researchers, who reported their findings in the July 2004 Journal of Global and Planetary Change, found that a 1979 tremor in the southern part of the state, known as the St. Elias earthquake, correlated with shrinking and disappearing glaciers in the same region. They calculated that this ice loss would have been sufficient to trigger the quake, which had a magnitude of 7.2 on the Richter Scale.—Laura Tangley