Washington, D.C. ? Polar bears are in jeopardy and need stronger government protection because of melting Arctic sea ice related to global warming, the Bush administration said Wednesday.

The Interior Department cites thinning sea ice as the big problem; outside the government, other scientists studying the issue say pollution, overhunting, development and even tourism also may be factors. Greenland and Norway have the most polar bears, while a quarter of them live mainly in Alaska and travel to Canada and Russia.

Interior Secretary Dirk Kempthorne on Wednesday proposed listing polar bears as a “threatened” species on the government list of imperiled species. The “endangered” category is reserved for species more likely to become extinct.

“Polar bears are one of nature’s ultimate survivors, able to live and thrive in one of the world’s harshest environments,” Kempthorne said. “But we are concerned the polar bear’s habitat may literally be melting.”

A final decision on whether to add the polar bears to the list is a year away, after the government finishes more studies.