How Is Climate Change Affecting Polar Bears In Alaska?

Polar bears in the Beaufort Sea in Alaska usually spend summers in areas of mixed ice and water near the ice cap edges in shallow waters over the continental shelf. They find plenty of food there as their main prey, ringed seals (Phoca hispida) and bearded seals (Eriginathus barbatus), also inhabit this environment.

In recent years, the effect of global warming has been to melt the ice more rapidly and more extensively at the edges of the ice cap. This has forced most polar bears to spend the summer in the deepwater ice habitat more than 200 km from the mainland coast.

Changes in living patterns have also been seen in the two seal species. Some ringed seals travel along the ice edge as it retreats north, moving out of reach of the polar bears. Other seals have switched to life in the open water, where seals can't reach them either. Bearded seals feed from the sea bottom and so are not easy for the polar bears to catch in deeper water

To add to the problems of polar bears, many pregnant Alaskan polar bears settle on the active sea ice when breeding but warmer temperatures has thinned this ice. Polar bears have to use winter ice instead, which may not be stable enough.

With diminishing prey, shifting ice and fewer places to breed, global warming could pose a real challenge to the polar bear.