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It's a sign of the times. The polar bear, that beautiful but deadly hunter of the Arctic, may become the first animal placed on the U.S. Endangered Species list because of global warming.

Polar bears range across the northern reaches of five countries: Canada, the U.S. (Alaska), Russia, Norway (Svarlbard Archipelago), and Denmark (Greenland). The great white bears (Ursus maritimus) are superbly adapted to their Arctic home. Polar bears' hollow, colorless fur looks white in their snowy environment; their black skin acts as a solar panel, warming the bears; and their finely attuned senses of hearing and smell allow them to detect seals under the ice. Polar bears wait at seals' breathing holes to ambush adults, or find dens with young seals hidden under the snow and ice. They are utterly dependent on sea ice packs for survival; the ice is where they hunt, mate, and travel from one hunting area to another. Sometimes, mother polar bears even make their maternity dens on the ice.

But the sea ice is disappearing, as Arctic temperatures soar faster than any other region on Earth. Just between 2004 and 2005, the ice shrank by more than 14%. The total area lost was about the size of Texas, in only one year!

Polar bears are shifting their behavior in a desperate attempt to find food in the face of this disaster. One disturbing study found that only 33% of polar bears spotted between 1992 and 2004 were found on the shrinking sea ice. This was down from 87% between 1979 and 1991. Most were swimming in the ocean, or clustered around whale carcasses on the beach. Previously, polar bears wouldn't have bothered with human hunters' left-over whale bones; they would have been out hunting nice fatty seals on the ice.

Already the strain of this poor diet is beginning to show. Polar bears' average weight has decreased by more than 30% in just the past 15 years. People are finding drowned bears on Alaska's beaches; although they are normally strong swimmers, the hungry bears don't have enough energy to make the long trips that used to be routine.

Polar bears can't simply switch to eating caribou or salmon, like their grizzly cousins. The white bears have adapted for such an extreme environment that they need calorie-rich, high-fat food such as seals in order to survive. As the ice disappears, so do the seals. When the seals go, the polar bears starve to death.

If polar bears are listed on the Endangered Species list, it could have a dramatic effect on thousands of US companies. The

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