"Such events can only become more frequent in the future because increased greenhouse gas levels guarantee that the climate will continue to warm, and a warmer world means less sea ice-in Hudson Bay and elsewhere. Scientists have projected that polar bears could disappear entirely by the end of the century if greenhouse gas emissions are not reduced," said Dr. Steven Amstrup, Polar Bear International's senior scientist.

Polar bears are completely dependent upon large expanses of sea ice to hunt, feed and survive. They use the sea ice as a platform to capture seals and other prey. Polar bears in western Hudson Bay must come to land each spring when the sea ice melts. While onshore the bears fast until the ice freezes again losing up to 30 percent of their body mass.

Twenty years ago, the average date the bears returned to the ice was November 8. A decade ago that date stretched to November 20. In 2009 the bears returned to the ice on approximately December 4, and in 2010 the bears begun to return to the ice around December 7.

The western Hudson Bay polar bear population declined 22 percent between 1987 and 2004. If current trends persist it will likely be the first polar bear population driven extinct by global warming.