Scott Schliebe / USFWS
Most of the world’s polar bears — including all of the bears living near Alaska — will disappear over the next 50 years with the immense retreat of the Arctic’s summer ice cap, according to a battery of studies released Friday by the U.S. Geological Survey.
Two-thirds of the polar bears scattered over Far North will die out, starve, fail to reproduce, cannibalize each other and drown because the disintegration of the summer cap will eliminate about 42 percent of their essential habitat. The process is irreversible, the scientists say.
Because of this ice loss, the species has been proposed to be listed as threatened with extinction under the federal Endangered Species Act. After receiving hundreds of thousands of comments on the proposal, the U.S. Fish and Wildlife Service is now working on a final decision, expected by 2008.
The studies released Sept. 7 were conducted by USGS biologists, including polar bear expert Steve Amstrup, as part of this ESA review. A new story about the reports says more:
Polar bears depend on sea ice as a platform to hunt seals, their primary food. But sea ice is decreasing throughout their Arctic range due to climate change. Models used by the USGS team project a 42 percent loss of optimal polar bear habitat from the Polar Basin during summer, a vital hunting and breeding period, by mid-century.
In addition to forecasts, declines in habitat have been recorded throughout the Polar Basin over the past 20 years of observations. To project future sea ice conditions, USGS scientists used 10 general circulation models that best approximated observed trends in sea-ice loss and could be expected to do the best job of simulating future conditions.