The fate of polar bears could be even bleaker¹ 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 mid² 21st century," the report's executive summary said.

"Because the observed trajectory³ of Arctic sea ice decline appears to be underestimated by currently available models, this assessment⁴ 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 prey⁵.

The research released on Friday was sent to the Fish and Wildlife Service. A decision on the bears' status is expected in January.

美国一项地质勘探报告称，由于北极圈海冰的融化速度可能比现有电脑模型所预测的要快，因此北极熊的命运可能比预计的要悲惨。该报告旨在确定是否将北极熊列为濒危物种。

研究小组组长史蒂夫•阿姆斯特拉普说：“北极海冰的融化与北极熊的命运有着必然联系。”据美国国家冰雪数据中心的统计数据，今年，北极圈的海冰总面积已创历史最低纪录，预计本月还将进一步缩小。

研究人员称，这意味着到2050年，约1万6千只北极熊将从海冰融化最快的阿拉斯加和俄罗斯北部海岸地区消失。

阿姆斯特拉普说，其余的大多数北极熊到2100年可能也将绝迹。到本世纪末，仅存的北极熊可能将生活在加拿大北极岛屿及格林兰岛的西海岸地区。

该报告的小结部分提到：“如果有关未来北极海冰变化的预测准确的话，到本世纪中期，目前全世界的北极熊数量将减少三分之二。”

“由于目前现有的模型对北极海冰融化速度的估计可能不足，所以对北极熊未来命运的估计可能有些保守。”

今年1月，美国鱼类及野生动物保护局提议将北极熊列入《濒危物种法案》的濒危物种名单，并指出北极熊主要依靠海冰这一“平台”来捕食海豹。

该项于上周五公布的研究已提交至美国鱼类及野生动物保护局。北极熊是否将被列为濒危物种将于明年1月揭晓。