(CNSNews.com) - Polar bears have become an "icon" of the global warming movement, but the fate of the creatures and the role played by climate change remains the subject of dispute among scientists.
According to animal experts linked to the World Conservation Union, polar bears are in trouble as sea ice recedes and global warming accelerates, and habitat loss will impact at least the next three generations of polar bears.
The World Wildlife Fund (WWF) in Canada has warned global warming could ultimately lead to the eradication of the species.
"If current trends continue, polar bears may vanish from large portions of their current Canadian range before the end of this century," WWF says in an online position paper.
But Willie Soon, a climate scientist based in Massachusetts, is among those raising questions about some of the most recent research on polar bears. He contends that polar bear populations have actually been increasing since hunting restrictions were initiated in the early 1970s.
Soon also said there has been too narrow a focus on the bears' Western Hudson Bay population - one of a total of 19. (Polar bears are reportedly found in 15 locations in Canada, as well as one each in Alaska, Denmark, Norway and Russia.)
A suggested link between global warming and polar bear survival is on loose footing, he argues.
In his own report on the subject, Soon said some of the temperature data is misleading, because it is drawn from warm months like September.
Studies that claim polar bears are unlikely to survive are problematic, he said, because the climate models that foresee a disappearance of sea ice focus on late summer - a period when the Hudson Bay is largely ice-free anyway, regardless of any human influence on greenhouse gas emissions, he said.
Soon said broad claims about the disappearance of sea ice before the end of the 21st century could be "misleading and confusing."
A fixation with global warming could divert attention from other "mechanisms" affecting polar bear population and health of the species, he told Cybercast News Service.
These other factors include bear interactions with humans in the Western Hudson Bay area, food availability and reproduction rates, he said.
Mitch Taylor, a polar bear expert with the Department of the Environment in Canada's far-northern Nunavut territory, has reported that the Canadian population has actually increased by 25 percent over the past 10 years.
Contrary to what is implied in former Vice President Al Gore's movie (see related story) and the views of some animal specialists, James Taylor, a senior fellow of environmental policy at the conservative-leaning Heartland Institute, also does not believe the polar bear population is declining.
Taylor told Cybercast News Service in a series of email messages that the Antarctic ice mass is actually growing, the Greenland ice mass is in "rough balance," and polar bears are not drowning.
"The polar bear drowning myth is typical of the deceit practiced by many global warming alarmists," he said. "Polar bears are very strong swimmers and have been documented swimming more than 60 miles without interruption."
In 2004, researchers with the U.S. Minerals Management Service found four dead polar bears floating in the sea after a severe storm off the Alaskan coastline and attributed their deaths to the storm. These same researchers had observed the bears swimming longer distances in the past few years.
Proponents of global warming, such as Gore, believe polar bears could be jeopardized as ice glaciers break up.
One of the first signs of trouble scientists look for when examining polar bear populations is a drop in body weight that suggests nutritional stress, explained Andrew Derocher, a professor of biological sciences at the University of Alberta. Other key indicators are the cub survival rate and cub production among females, he added.
Some of the most disturbing trends have been observed in Western Hudson Bay where the population has dropped by about 22 percent in the past 10 years, Derocher said in an interview.
A "large portion" of the population decline is attributable to climate change and sea ice dynamics although "excessive harvesting" by humans is another factor, he said.
Derocher has chaired the World Conservation Union's specialist group on polar bears since 2005, when the organization last reported on the species' status.
He told Cybercast News Service the anticipated rate of habitat loss over the next four to five decades is enough to deplete the population by at least a further 30 percent.
Historical patterns show polar bears living off the coast of Alaska would produce two-thirds of their young on sea ice and one-third on land, Derocher said. In recent years, however, two-thirds of the young are born and raised on land.
"It looks like the sea ice is not as stable as it used to be," Derocher said.
Yet even Derocher is cautious when it comes to the issue of bears drowning. While instances of drowned bears would be symptomatic of global warming, they could not be called definitive proof, he said.
"I'm sure other polar bears have drowned in the past, and it was just never documented," he said.
Derocher said the polar specialist group that he chairs unanimously agrees with the need to list polar bears as being "vulnerable" under the internationally agreed-upon definition found on the red list of threatened species.
'Don't rush policy changes'
Lee Foote, an associate professor specializing in wildlife ecology and management at the University of Alberta, believes that climate change is a large and important factor in impacting the polar bear habitat. At the same time, however, he is calling for additional research to precede any "overarching policy changes."
A decision to list polar bears as an endangered species - as proposed by the Bush administration last December - would be premature, Foote said. He also noted that Inuit communities could suffer economically if the bears were listed as endangered.
There are polar bear populations in the most northern regions that are not as well known as the Western Hudson Bay one, and their number may be on the increase in those areas, Foote told Cybercast News Service.
"Polar bears are being used as an icon of global climate change, yet [changes in] populations of these bears are a response to, not a cause of, climate change," Foote said in recent congressional testimony.
"Regardless of bear populations, climate will be unaffected by them. Hence, more protections for bears is illogical in remedying climate change," he added.
Make media inquiries or request an interview about this article.
Subscribe to the free CNSNews.com daily E-Brief.
E-mail a comment or news tip to Kevin Mooney.
Send a Letter to the Editor about this article.