ANCHORAGE - Melting ice could spell the ruin of polar bear populations over the next century, warns a report by an international panel of experts on the subject.
If warming climate in the Arctic continues to erode sea ice, the white carnivores will be driven ashore or onto increasingly smaller floes in hunt for seals, the World Conservation Union warned last week.
The 40 members of the polar bear specialist group said the population of the Arctic's top predator could crash by 30 percent over the next 35 to 50 years and should now be rated as vulnerable on an international "Red List" of threatened species.
"This is the first time that we've evaluated the plight of polar bears (with) respect to climate change, and we found that they were vulnerable to extinction," said the group's outgoing chairman, biologist Scott Schliebe, who oversees management of polar bears in Alaska for the U.S. Fish and Wildlife Service. "Polar bears don't have a place to go if they lose the ice."
Over the past decades, sea ice has lost thickness, melted faster in spring and re-formed later in fall, according to the international Arctic Climate Impact Assessment. Vast stretches near Alaska have become ice-free during the last three summers, setting a record in 2003 and a near-record in 2004 for least coverage ever measured. The thick multiyear ice essential to polar bears has been shrinking 8 to 10 percent per decade.
Some climate models predict summer ice could disappear from the Arctic Ocean by the end of the century.
"It's now abundantly clear that we're looking at a retraction of the sea ice environment," Schliebe said. "The projection from the climatologists is very grim."
Politicians who could do something about reducing the greenhouse gas emissions that are at least partly responsible for heating the earth have been reluctant to act. The U.S. Senate passed a nonbinding resolution last week acknowledging the role of human-generated greenhouse gases in causing the climate to warm and suggesting that U.S. emissions should be cut back, but Alaska Sens. Ted Stevens and Lisa Murkowski voted against a measure that would have imposed limits on those emissions.
Murkowski has said she wanted to see more conclusive evidence tying climate change to man-made releases before taking actions that could hurt the U.S. economy.
Although the polar bear group named climate warming and the destruction of the ice habitat as the main threat to the species, it also cited poaching in Russia and threats by contaminants as other problems.
The group, which advises the United States and other Arctic nations on polar bear biology and treaty obligations, last rated the animals in a category of "least concern" in 2001 but had not yet considered the impact of climate change, Schliebe said.