The U.S. Geological Survey said Friday the two-thirds of all polar bears living in Alaska and Russia will likely die due to loss of summer sea-ice habitat, and only a tiny surviving population will remain on islands in the Canadian Arctic, the Anchorage Daily News reported.

Furthermore, there is nothing humans can do to save the bears, the scientists estimate, because efforts to control greenhouse gas emissions and limit hunting and gas development cannot outweigh the effects of habitat loss.

The prediction was prepared as Interior Secretary Dirk Kempthorne is deciding whether to designate polar bears as a threatened species, the newspaper said.

Some conservationists criticized the defeatist language in the survey, saying it is not too late for difference-making efforts to save the bruins.