Study Says Polar Bears Could Face Extinction

Global warming could cause polar bears to go extinct by the end of the century by eroding the sea ice that sustains them, according to the most comprehensive international assessment ever done of Arctic climate change.

The thinning of sea ice -- which is projected to shrink by at least half by the end of the century and could disappear altogether, according to some computer models -- could determine the fate of many other key Arctic species, said the Arctic Climate Impact Assessment, the product of four years of work by more than 300 scientists.

Bears are dependent on sea ice because they use it to hunt for seals, which periodically pop up through breathing holes in the ice. Because the ice has broken up earlier and earlier in the year over the past few decades, polar bears are deprived of crucial hunting opportunities.

The uncertain fate of the world's largest non-aquatic carnivores -- as well as the future of other animals and humans who live in the Arctic -- was sketched in stark relief yesterday by the 139-page document.

The report offered a broad picture of the evidence that climate change has disproportionately affected far northern latitudes.

The researchers concluded that some areas in the Arctic have warmed 10 times as fast as the world as a whole, which has warmed an average of 1 degree Fahrenheit over the past century.

"The Arctic is really warming now," said Robert Corell, a senior fellow at the American Meteorological Society who chaired the assessment. "These areas provide a bellwether of what's coming to planet Earth."

In Alaska, western Canada and eastern Russia, average winter temperatures have risen as much as four to seven degrees Fahrenheit within the past 50 years, according to the report and are projected to increase an additional seven to 13 degrees over the next century. Winter temperatures have risen faster than summer temperatures, according to Michael MacCracken, chief scientist for climate change programs at the Washington-based Climate Institute, because thin sea ice releases more energy from the ocean into the atmosphere.

The sea ice in Hudson Bay, Canada, now breaks up 2 1/2 weeks earlier than it did 30 years ago, said Canadian Wildlife Service research scientist Ian Stirling, and as a result female polar bears there weigh 55 pounds less than they did then. Assuming the current rate of ice shrinkage and accompanying weight loss in the Hudson Bay region, bears there could become so thin by 2012 they may no longer be able to reproduce, said Lara Hansen, chief scientist for the World Wildlife Fund.

"Once the population stops reproducing, that's pretty much the end of it," Hansen said.

Arctic residents have already detected changes in polar bears' behavior. Jose Kusugak, president of the Canadian Inuit political association, said at a news conference that within the past two years he witnessed a polar bear "stock up on caribou" because it was deprived of seals. Hudson Bay residents now complain the bears are coming onto land more often, forced to seek sustenance in a habitat where they are less well adapted.

Polar bears are not the only Arctic animals in trouble. The ringed seals that bears eat, and that humans hunt, are also dependent on the sea ice to rest, give birth, nurse and feed.

"You have organisms that have been pushed beyond their limits," said James McCarthy, director of the Harvard University Museum of Comparative Zoology.

While some questioned the report -- Los Alamos Laboratory atmospheric scientist Petr Chylek said he has charted declining temperatures at the summit of Greenland's ice sheet between 1986 and 2003 -- environmentalists said it shows the need for stricter curbs on greenhouse gas emissions linked to global warming.

"This study is the smoking gun. Skeptics, polluting industries and President Bush can't run away from this one," said Philip E. Clapp, president of the National Environmental Trust. He added the study showed "concrete evidence that global warming pollution is already having serious impacts."

Administration officials, who oppose mandatory curbs on carbon emissions on the grounds that it will cost U.S. jobs, said yesterday that they consider Arctic climate change an important issue and will work to draft policy recommendations for the region. Some European negotiators have complained that the U.S. State Department is resisting issuing policy guidelines based on the scientific study, a charge Bush officials deny.

"The United States is committed to working within the United Nations framework and elsewhere to develop an effective and science-based global approach to climate change that ensures continued economic growth and prosperity for our citizens and for citizens throughout the world," said State Department spokesman Richard Boucher.

Polar Bear Headed For Extinction

Unless the pace of global warming slows or stops, polar bears could disappear within a century, says a University of Alberta expert in Arctic ecosystems.

While it has been known for some time that the polar bear is in trouble, new research shows that Arctic ice - the polar bear's primary habitat - is melting much faster than scientists had believed, says U of A biologist Dr. Andrew Derocher.

"The climate predictions coming out are showing massive changes in sea-ice distribution," said Derocher, who follows polar bears to see how they adapt to changing conditions. If the predictions are correct, he says, "we'll certainly lose polar bears in a lot of areas where we currently have them." Ice conditions in the Beaufort Sea, for example, are already changing dramatically.

The world's largest terrestrial carnivores, polar bears rely on sea ice to survive, using it to pass between forest dens and hunting grounds where they prey on seals. There are about 15,000 polar bears in northern Canada, accounting for about two-thirds of the world's total population.

Derocher shared his views Jan. 6 at a symposium on Arctic biology in Toronto. It was the biggest gathering of Canadian Arctic biologists in more than a decade, says co-chair Dr. David Hik, also of the U of A. Many of the talks addressed the impact of climate change on northern ecosystems.

Derocher says if global warming continues unchecked, some remnant populations of polar bears may manage to hang on in the high Canadian archipelago or on permanent polar ice at very high latitudes. But the potential for extinction is still a cause for concern: "You don't have to be a polar scientist to see that if you take away all the sea ice, you don't have polar bears any more."

To make matters worse, sea-ice melting is accelerated by "positive feedback loops." Sea ice acts as a reflector of solar energy, but when the ice disappears, the ocean absorbs that heat energy, which in turn prevents ice from freezing.

"Once climate warming initiates, you get into a self-warming cycle," said Derocher, who earned international renown as a polar bear and northern studies expert at the Norwegian Polar Institute in Tromso before returning to the University of Alberta, where he completed his doctorate. "That's why the urgency on the issue for polar bears now."

He adds that it is possible a warmer climate will improve polar bear and seal habitats in the short term, mainly in higher latitudes where ice is too thick for seal hunting. But these areas are small, he says, and will only support a fraction of the bear population.

Polar bears can tolerate some environmental variation from year to year, foregoing reproduction in any given year if conditions are poor." With too much variation, however, reproduction will fall off dramatically, and populations will quickly decline. Scientists have no evidence yet of a drop in polar bear populations, but body weights and reproductive rates of bears in the Hudson Bay are on the decline," said Derocher.

Hik says there is also new research looking at the harmful effect of drought-related forest fires on polar bear dens, which are built in mature forests.

"When you burn the forest down, it blackens the earth, and these dens burrowed into the permafrost collapse," said Hik. "Many of them are created over centuries by successive generations of bears scraping deeper and deeper in." The area around Churchill, Manitoba is one such area that has been losing these dens.

polar bears are disapearing..

polar bears are disappearing because of starvation. they are starving because their food is dying off because of lack of fish. the polar bears homes are disappearing because they are melting due to global warming. if we don't do something to stop the polar bears home from being destroyed then they will die off before our kids even have kids. and i don't think anyone wants that to happen. so we must help the polar bears before its to late!