• Polar bear in Wapusk National Park, Manitoba. (Photo: Ansgar Walk/Wikimedia Commons)

Loss of sea-ice habitat due to climate warming has been highlighted as the single most important threat to the long-term survival of polar bears, and could see the animal’s population decline by more than 30 per cent over the next 35 to 40 years, says the International Union for Conservation of Nature.

The prediction headlined the IUCN’s release of its updated Red List of Threatened Species, which includes 79,837 assessed species, 23,250 of which are threatened with extinction.

“Based on the latest, most robust science, this assessment provides evidence that climate change will continue to seriously threaten polar bear survival in the future,” said Inger Andersen, IUCN director general. “Climate change impacts go far beyond this iconic species, and present a threat our planet has never faced before.”

The IUCN update said that recent studies show that the loss of Arctic sea ice has progressed faster than most climate models had predicted, with September sea ice extent declining at a linear rate of 14 per cent per decade from 1979 through 2011.

“As polar bears rely on sea ice to access their prey, an annual ice-free period of five months or more will cause extended fasting for the species, which is likely to lead to increased reproductive failure and starvation in some areas,” the IUCN update said. “According to recent sea ice projections, large regions of the Canadian Arctic Archipelago will be ice free for more than five months by the late 21st century; and in other parts of the Arctic, the five-month ice-free threshold may be reached by the middle of the 21st century.”