KAKTOVIK, Alaska — In Betty Brower’s memories, there is always ice. Even in the summer, when the sea around Barter Island was open, she could look out and see the jagged shapes of icebergs on the horizon.

Brower is 81 years old, a great-grandmother who has lived all her life along the northern coast of the Beaufort Sea, the last 60 years in this Inupiat village of about 250 people on Barter Island. In the mid-1990s, summer ice began to disappear, she said recently, speaking in Inupiaq as her daughter Marie Rexford interpreted. The period of open water grew longer, she said. And then came the bears.

Polar bears used to spend time on the ice far from shore hunting seals, she said. But when the ice vanished, they began ambling on land more often than before. Soon villagers were seeing more of them than anybody could remember, especially the last few years.

Local people alerted scientists with the U.S. Fish and Wildlife Service. Scientists discovered that the bears, without easy access to the ice, had fewer opportunities to hunt seal. They were smaller than they used to be, and their cubs were less likely to survive their first year, studies found. In 2008 polar bears were listed as threatened under the U.S. Endangered Species Act because of the ice’s decline.