The current issue of
Ecological Applications has a published study, researched by scientists from Canada and the U.S.:
In the southern Beaufort Sea of the U.S. and Canada, prior investigations have linked declines in summer sea ice to reduced physical condition, growth, and survival of polar bears. Combined with projections of population decline due to continued climate warming and the ensuing loss of sea ice habitat, those findings contributed to the 2008 decision to list the species as threatened under the U.S. Endangered Species Act. Here, we used mark-recapture models to investigate the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010, years during which the spatial and temporal extent of summer sea ice generally declined. Low survival from 2004 through 2006 led to a 25-50% decline in abundance.
The LA Times points out:
Perhaps even more worrisome, just two of 80 polar bear cubs that the international team tracked between 2003 and 2007 survived, according to the study. Normally about half of the cubs live.
There are hypotheses as to what is happening specifically—disadvantageous ice conditions for the bears (i.e. longer and more stressful swims in search of food and final shelter) and diminishing prey are two posited by the researchers. What is clear is that climate change and yes,
global warming in the Arctic, is leading to the potential extinction of the polar bear.
Conservationists have predicted that more than two-thirds of the world’s polar bear subpopulations could be extinct by 2050.
“We’re very worried that eastern Alaska’s polar bears may be among the first to go,” Uhlemann said. “The United States and the world have to get serious about reducing greenhouse gases if we want polar bears to survive.”