A confrontation between big oil and environmentalists opens today in Alaska when America invites bids for millions of acres of polar bear habitat in the Chukchi Sea, where 15 billion barrels of crude oil lie waiting to be tapped. Bidding will get under way days before a ruling on whether the animal, the poster child for the ravages of global warming, should be added to the list of endangered species.

The US Fish and Wildlife Service was supposed to make that decision in January but postponed the ruling by a month, saying that the matter needed more examination. Environmentalists have accused the Government of delaying the polar bear's designation deliberately for fear of complicating the sell-off.

Native Alaskans and environmentalists will be in court to try to halt the sale, while Senator John Kerry, the Democratic presidential candidate in 2004, is trying to push legislation through the Senate to insist that the bear's status is settled before the auction can begin.

Brandon Frazier, of the International Fund for Animal Welfare, said: “An endangered listing can affect the sell-off of the oil-drilling rights. That's why the decision on the polar bear has been delayed. They are trying to wait it out, get the lease sale through and then make the decision.”

Pictures of exhausted and emaciated polar bears clinging forlornly to shrinking ice floes have become icons of the global movement to halt climate change. Populations are in sharp decline, a trend that environmentalists blame on the shrinking of their sea ice habitats because of man-made global warming. Critics say that the global polar bear population, at 25,000, is far from extinction and question the human hand in their decline. The US Geological Survey, however, estimates that two thirds of polar bears will die off by the mid-century if sea ice continues to melt at the expected pace.

Listing an animal under the Endangered Species Act compels the US Government to protect it. If the polar bear were to be added to the list, it would create an extraordinary political and environmental precedent. The factors that have propelled other species on to the list include hunting and habitat loss. If the polar bear were to be listed as endangered, it would recognise for the first time global warming as a factor in the threatened extinction of a species and, environmentalists say, compel the Government to halt climate change. A more immediate danger to the bears could be any spillage of oil during drilling in the Arctic.

The agency in charge of the oil and gas drilling rights, the Minerals Management Service, is part of the US Interior Department. Another agency in the same department, the Fish and Wildlife Service, is responsible for the listing of endangered species. Critics see this as a conflict of interests. US officials insist that the sale of drilling rights poses no threat to the polar bear, making the timing of the endangered ruling irrelevant.

Mr Kerry's new Bill calls for the sale to be postponed until after the ruling on the bear's status, to allow for more research to be conducted. He told the Senate: “Before the Government sells even more of their habitat off to big corporate interests, we need to know the full impact of further drilling. We need to know whether this would push us past the tipping point and devastate the polar bear habitat.”

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