Most polar bears gone by 2050
2007-09-08 13:33
Washington - Two-thirds of the
world's polar bear population could be gone by midcentury if
predictions of melting sea ice hold true, the US Geological
Survey reported on Friday.
The fate of polar bears could be even bleaker than that
estimate, because sea ice in the Arctic might be vanishing
faster than the available computer models predict, the
geological survey said in a report aimed at determining whether
the big white bear should be listed as a threatened species.
"There is a definite link between changes in the sea ice
and the welfare of polar bears," said Steve Amstrup, who led
the research team. Arctic sea ice is already at an all-time low
this year and is expected to retreat farther this month,
according to the US National Snow and Ice Data Centre.
That means that polar bears - some 16 000 of them - will
disappear by 2050 from parts of the Arctic where sea ice is
melting most rapidly, along the north coasts of Alaska and
Russia, researchers said in a telephone briefing.
Other polar bear populations could survive beyond that date
but many of those could be gone by 2100, Amstrup said. By
century's end, the only polar bears left might live in the
Canadian Arctic islands and along the west coast of Greenland.
"Projected changes in future sea ice conditions, if
realised, will result in loss of approximately two-thirds of
the world's current polar bear population by the mid 21st
century," the report's executive summary said.
"Because the observed trajectory of Arctic sea ice decline
appears to be underestimated by currently available models,
this assessment of future polar bear status may be
conservative."
In January, the US Fish and Wildlife Service proposed
listing the polar bear as a threatened species under the
Endangered Species Act, noting polar bears depended on sea ice
as a platform to hunt seals, their main prey.
The research released on Friday was sent to the Fish and
Wildlife Service. A decision on the bears' status is expected
in January.
Without enough sea ice, polar bears would be forced onto
land, but they are inefficient hunters once they get out of the
water and ice, the researchers said. The bears' disappearance
would probably take place as young cubs failed to survive to
adulthood and females were unable to reproduce successfully.
The first polar bears probably first appeared about 40 000
to 50 000 years ago, and the species has not lived through a
period as warm as the one predicted by the UN
Intergovernmental Panel on Climate Change, the scientists
said.
In a series of reports this year, the U.N. climate panel
said with 90% probability that global climate change was
occurring and that human activities contributed to it. The
emission of greenhouse gases - including carbon dioxide from
petroleum-fueled vehicles and coal-fired power plants - is the
prime human cause of this warming trend, the panel said.