英语听力：自然百科 当北极变成无冰海洋

Data released this week by a team of explorers who trekked through the Arctic for three months this spring shows that North Pole will be an open sea during the summer months within 20 years. The Catlin Arctic Survey team, led by explorer Pen Hadow, measured the thickness of the ice as they sledged and hiked through the northern part of the Beaufort Sea in thegeographic North Pole. Their findings show that most the ice in the region is first-year ice that is only around six feet thick and will melt next summer. The region has traditionally contained thicker, multi-year ice which doesn't melt as rapidly. The results come as negotiators prepare to meet in Copenhagen in December to draft a global climate pact.

Their conclusions from this work and from other measurements that have been done and from new models are that the summer ice will disappear within 20 to 30 years, and it will be, a lot of it will be gone within 10 years. And it will retreat to a fairly small area north of Greenland within about a decade, and then the rest of the ice pool will disappear during the following decade.

These results are significant because they highlight the urgency, they highlight how and important aspect of the climate system is actually much more vulnerable to climate change than we thought.

Sommerkorn noted that the Arctic sea holds a central position in the earth's climate system, and loss of Arctic ice could impact the climate of the regions way beyond the Arctic itself. Potential consequences include flooding affecting a quarter of the world's population, significant increases in greenhouse gas emissions from massive carbon pools, as well as extreme global weather changes. Global warming has raised the stakes in the scramble for sovereignty in the Arctic because shrinking polar ice could someday open resource development and new shipping lanes. The rapid ice melting has raised speculation that the Northwest Passage linking the Atlantic and Pacific oceans could one day become a regular shipping lane.