Polar Bear Populations Shrinking as Arctic Ice Melts

GLAND, Switzerland, December 15, 2006 (ENS) - Polar bears are losing their icy Arctic habitat to climate change, and five out of the world's 19 polar bear populations are now in decline, polar bear experts said in a report released today.

A 30 percent decline in the size of the total polar bear population within the next 35 to 50 years is likely, the IUCN-World Conservation Union’s Polar Bear Specialist Group said in its report. An estimated 20,000 and 25,000 polar bears exist today.

Polar bear stands on the edge of a melting ice floe on the Chukchi Plateau between the United States and Russia. 2003. (Photo by Kathy Crane courtesy NOAA Arctic Research Office)

The Polar Bear Specialist Group reports that the two best studied polar bear sub-populations in the world have declined over the past two decades.

The western Hudson Bay population in Canada has declined by 22 percent during that period, and the southern Beaufort Sea population in the United States and Canada has declined by 17 percent.

The other three populations in decline are those in Baffin Bay and Kane Basin – shared between Greenland and Canada – and Norwegian Bay in Canada.

"Climate change is the main threat to polar bears and is clearly implicated in the western Hudson Bay sub-population. It is likely also a key factor in the Southern Beaufort Sea,” said Professor Andrew Derocher of the University of Alberta, who chairs the IUCN Polar Bear Specialist Group.

“Climate stabilization is the key conservation action now for polar bears," Derocher said.

Dr. Andrew Derocher, chair of the IUCN Polar Bear Specialist Group measures the skull length of an adult male polar bear to assess age related growth patterns. (Photo courtesy U. Alberta)

The report's findings have prompted WWF to issue an urgent call to action to the governments of the world to cut carbon pollution, the cause of Arctic warming

Declining populations of polar bears indicate that the entire Arctic is under immense stress as a result of climate change, WWF warned.

"The polar bear’s powerful grip on the Arctic is slipping," said Stefan Norris, head of conservation with the WWF International Arctic Programme.

"We need to stop run-away warming," Norris said. "Climate change is melting the ice-bear’s toe-hold on life. This bad news for polar bears is also bad news for other Arctic species, and for the indigenous peoples whose traditional ways of life depend on them."

In May, polar bears for the first time were listed as Vulnerable to extinction on the IUCN Red List of Threatened Species.

Polar bears are treated separately from the other bear species, because the management of polar bears is guided by the International Agreement on the Conservation of Polar Bears signed in Oslo, Norway in 1973 by the five polar range states - Canada, Denmark, Norway, USA, and the former USSR. The Agreement is the action plan for polar bears.

The Polar Bear Specialist Group has 16 members, all research scientists from the five polar bear range states.

The Polar Bear Specialist Group meets every three to five years to review and exchange information on progress in the research and management of polar bears throughout the Arctic and to review the worldwide status of polar bears.

The newly published report is the proceedings of the 14th meeting of group that was held in Seattle, Washington June 20–24, 2005, under the chairmanship of Scott Schliebe of the U.S. Fish and Wildlife Service. The chairmanship of the Polar Bear Specialist Group was passed to Professor Derocher at the Seattle meeting.

Polar bear standing on the Chukchi Plateau (Photo by Kathy Crane courtesy NOAA Arctic Research Office)

A new analysis of the long-term subpopulation data base in Western Hudson Bay detailed in the Group's report confirms the size of that subpopulation has declined from 1,200 to less than 1,000.

The Group concludes the decline was caused by reductions in condition and survival, especially of young bears, because climatic warming has caused the sea ice to break up about three weeks earlier now than it did only 30 years ago. As a result, polar bears have less time to feed and store the fat needed to survive on shore for four months before the ice refreezes.

Significant reductions in the apparent survival of ringed seal pups and changes in the diet of sea birds in northern Hudson Bay, coincident with larger amounts of open water earlier in the summer, have also been reported.

"Taken together," the Group states, "these results suggest that unknown changes in the marine ecosystem of Hudson Bay are now underway."

Similarly, the minimum extent of multi-year ice in the polar basin continues to decline at the rate of eight to 10 percent per decade, resulting in unusually extensive areas of open water in regions such as the Beaufort/Chukchi Seas and East Greenland.

High levels of PCBs and pesticides were found in East Greenland polar bears. There was a strong indication of a relationship between contaminants and skull mineral density, indicating possible disruption of the bone mineral composition, the Group reports, saying the changes were related to aging, infections and chronic exposure.

The Group emphasized the importance of continuing to monitor polar bear subpopulations in order to quantitatively assess the affects of climatic warming and of contaminants on polar bears.

The entire Polar Bear Specialist Group report can be read online here.