美國：北極熊命運堪憂

The fate of polar bears could be even bleaker than that estimate

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 Center.

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.

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 realized, 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.

美國一項地質勘探報告稱，由於北極圈海冰的融化速度可能比現有電腦模型所預測的要快，因此北極熊的命運可能比預計的要悲慘。該報告旨在確定是否將北極熊列爲瀕危物種。

研究小組組長史蒂夫•阿姆斯特拉普說：“北極海冰的融化與北極熊的命運有着必然聯繫。”據美國國家冰雪數據中心的統計數據，今年，北極圈的海冰總面積已創歷史最低紀錄，預計本月還將進一步縮小。

研究人員稱，這意味着到2050年，約1萬6千隻北極熊將從海冰融化最快的阿拉斯加和俄羅斯北部海岸地區消失。

阿姆斯特拉普說，其餘的大多數北極熊到2100年可能也將絕跡。到本世紀末，僅存的北極熊可能將生活在加拿大北極島嶼及格林蘭島的西海岸地區。

該報告的小結部分提到：“如果有關未來北極海冰變化的預測準確的話，到本世紀中期，目前全世界的北極熊數量將減少三分之二。”

“由於目前現有的模型對北極海冰融化速度的估計可能不足，所以對北極熊未來命運的估計可能有些保守。”

今年1月，美國魚類及野生動物保護局提議將北極熊列入《瀕危物種法案》的瀕危物種名單，並指出北極熊主要依靠海冰這一“平臺”來捕食海豹。

該項於上週五公佈的研究已提交至美國魚類及野生動物保護局。北極熊是否將被列爲瀕危物種將於明年1月揭曉。