More than 25 percent of the world's polar bear populations are already in decline.
	The polar bear is considered a marine mammal -- like walruses, seals and whales -- because its main habitat is sea ice.
	The Arctic may be virtually free of summer sea ice by 2040 -- and without sea ice, polar bears cannot survive.
	As sea ice decreases, polar bear females may not gain enough weight to reproduce cubs with enough insulating fat -- jeopardizing their ability to survive.
	Polar bears, the world's strongest swimmers, are being forced to swim further and further to ever-distant ice floes. Four were found drowned in the Bering Strait.
	Newborn cubs were crushed to death when their snowy dens collapsed from unseasonable rains.

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