Cutting greenhouse gas emissions enough over the next few decades may stabilize the rapidly shrinking Arctic sea ice sufficiently to provide a sustainable habitat for polar bears, a paper in the Dec. 16 Nature reports. And if emissions do keep rising, another new study finds, the only species that has officially been declared threatened by the U.S. government due to global warming may still be able to hang on for a while in a few pockets of the northern Arctic.
Polar bears need sea ice to hunt their prey, but the frozen skin that floats atop the Arctic Ocean has been thinning and shrinking in recent decades as global temperatures rise. Between 1979 and 2010, Arctic sea ice cover at the end of the summer melt season dropped an average of 11.5 percent per decade. Many researchers think that end-summer Arctic ice could be almost entirely gone by the middle of this century.
In 2007, the U.S. Geological Survey reported that two-thirds of the world’s 25,000 polar bears could disappear within 50 years if greenhouse gas emissions continued unabated. The following year, interior secretary Dirk Kempthorne relied on that report when putting the bear, Ursus maritimus, on the government’s list of threatened species.