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Whew! Chukchi Sea polar bears are in good shape

Polar Bears
An adult female polar bear and a cub stroll on Wrangel Island in the fall of 2017. Hundreds of Chukchi Sea polar bears spend the summer months on the island. (University of Washington Photo / Eric Regehr)

The first census of polar bears living around the Chukchi Sea, straddling Alaska and eastern Siberia, suggests that the population has been stable and healthy over the past decade.

That comes as a welcome contrast to the problems facing polar bears in other Arctic regions as their sea-ice habitat shrinks. The loss of  sea ice is an issue for the Chukchi Sea as well, but the nearly 3,000 bears in that region don’t seem to be feeling the strain as much.

“Despite having about one month less time on preferred sea-ice habitats to hunt compared with 25 years ago, we found that the Chukchi Sea subpopulation was doing well from 2008 to 2016,” Eric Regehr, a biologist at the University of Washington’s Polar Science Center, said today in a news release.

Regehr is the principal author of a study about the census published in the open-access journal Scientific Reports. The census, conducted by researchers from UW and federal agencies, chronicles a decade’s worth of observations — and delves into why the Chukchi Sea bears seem to be faring better than their cousins elsewhere.

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Arctic sea-ice study is bad news for polar bears

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A polar bear tests the strength of thin Arctic sea ice. (Credit: Mario Hoppmann via Imaggeo.EGU.eu)

Scientists have long known that Arctic climate change is bad news for bears, but University of Washington researchers quantify just how bad it is in a study published today.

The study in The Cryosphere, a journal of the European Geosciences Union, is said to be the first to assess the impact of sea ice changes for 19 different populations of polar bears across the entire Arctic region, using the metrics that are most relevant to polar bear biology.

“This study shows declining sea ice for all subpopulations of polar bears,” Harry Stern, a researcher with UW’s Polar Science Center, said in an EGU news release.

The analysis draws upon 35 years’ worth of satellite data showing daily sea-ice concentration in the Arctic. There’s a consistent trend toward earlier thawing in the spring, and later freezing in the winter. Between 1979 and 2014, the total number of ice-covered days declined at the rate of 7 to 19 days per decade. Over the course of 35 years, seven weeks of good sea-ice habitat were lost.

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