Greenland’s ice is melting four times faster than thought—what it means

A polar bear watches her cubs on Hudson Bay in Manitoba, Canada. The bay is famous for polar bears, but their population is in decline.

Thanks to a camera trap, a polar bear unwittingly makes a self-portrait in Svalbard.

A polar bear jumps between ice floes near the island of Spitsbergen in Norway in 2010.

A red fox rubs noses with a polar bear on Hudson Bay in Manitoba, Canada.

A polar bear and her cubs are stranded on an iceless shoreline in Svalbard.

A polar bear sleeps on ice in Svalbard.

A polar bear swims in Admiralty Inlet in Nunavut, Canada.

Two polar bears face off against each other in Churchill, Manitoba, in northern Canada.

A polar bear sleeps with his paws folded underneath.

A polar bear stands over a partially eaten whale carcass in Kaktovik, Alaska.

A polar bear inspects photographer Paul Nicklen's cabin – his home while on assignment for National Geographic's 2009 article, "Paradise."

A polar bear and cubs walk away from the camera in Manitoba, Canada.