A U.S. judge has ordered the Bush administration to decide by May 15 whether polar bears in Alaska should be on the endangered species list because of global warming.

The judge ruled in favor of three conservation groups, including Greenpeace, that claim the U.S. government delayed a decision on the polar bear issue to avoid addressing global warming.

Environmental groups have argued the existence of the polar bears is threatened by the disappearance of their icy habitat due to global warming.

Under the Endangered Species Act, it is required that a decision to place species on the list be based on science. The conservation groups say science shows the Arctic is thawing.

Some information for this report was provided by AP and Reuters.