ANCHORAGE — Polar bear cubs in Alaska's
Beaufort Sea are much less likely to survive compared to about 20 years
ago, probably due to melting sea ice caused by global warming, a study
released Wednesday said.
The study, published by the U.S. Geological Survey, estimated that only 43
percent of polar bear cubs in the southern Beaufort Sea survived their
first year during the past five years, compared to a 65 percent survival
rate in the late 1980s and early 1990s.
"The changes in survival of cubs are very dramatic," said the study's
author Steven Amstrup, polar bear project leader for the USGS Alaska
Science Center.
The falling survival rate comes as a warming climate has melted much of
the sea ice off Alaska's northern coast, limiting polar bears from hunting
for food at the ice's edge, Amstrup said.
"The things we're observing are consistent with a population that is
undergoing nutritional stress," said Amstrup. "We can't say definitively
it's because of changes in the sea ice, but we don't know what else it
would be."
The study also found that adult male polar bears captured after 1990 were
smaller than those captured before then.
Co-authored by one of Amstrup's USGS colleagues and a scientist with the
Canadian Wildlife Service, the study provides information that might be
used by federal officials who are considering a proposal to give polar
bears protections under the Endangered Species Act.
Environmentalists have petitioned the U.S. Fish and Wildlife Service to
classify the bears as threatened because of new difficulties they are
facing from the warming Arctic climate.
A decision on the threatened listing is due by Dec. 27, said Fish and
Wildlife Service spokesman Bruce Woods.