Global warming and polar bears

It took the threat to an iconic mammal from the coldest reaches of the north to get the Bush administration to entertain a serious debate about global warming.

The U.S. Interior Department filed a proposal Wednesday in the Federal Register to list polar bears as a threatened species under the Endangered Species Act. The filing triggers a 90-day comment period, during which the agency will hold hearings and collect written testimony. The agency has been studying stresses on the polar bear, partly under pressure from a lawsuit from three environmental groups.

The move is significant, because the Bush administration has been reluctant to engage debate about the mounting evidence the world is warming and posing potential harm to the environment, wildlife and humans. A growing scientific consensus says human-generated greenhouse gases are contributing to global warming.

While the administration has all but resisted the connection, many states and cities, including Seattle, have started to raise awareness about the looming threat.

Solving the challenges facing polar bears is where the rub is in federal policy. About 4,700 of the world's polar-bear population, which might number as many as 25,000, live in Alaska and spend part of the year in Canada and Russia.

The government cannot merely curtail fishing or mandate localized habitat improvement as it might for an endangered fishery, or limit logging to protect northern spotted owl habitat. The forces threatening the bears are not simple to address.

Scientists have observed earlier seasonal melting of Arctic sea ice, which provides polar bears platforms from which to hunt. Bears have been found swimming in the open ocean — a few have drowned. The adults are skinnier, cubs are facing more difficult odds, and there's disturbing evidence that a few have resorted to cannibalism.

Interior's proposal acknowledging the bears are in trouble is a welcome sign that the federal government will engage more fully on the issue of global warming. This overdue conversation should begin in earnest.