北极冰层减到历史最低水平

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RENEE MONTAGNE, HOST: And I'm Renee Montagne.

Here's some troubling news. Ice covering the Arctic Ocean has melted more dramatically this year than ever before. This year's loss of ice has exceeded the previous record by an area the size of Texas. NPR's Richard Harris reports.

RICHARD HARRIS, BYLINE: The summer melt of Arctic iceis becoming more and more pronounced over the past few decades, but this year it has proven to be extraordinary. Ted Scambos at the National Snow and Ice Data Center says it shattered the previous record set five years ago.

TED SCAMBOS: I think it's an astonishing year and probably the thing that makes it most astonishing is that there was nothing particularly astonishing about the weather pattern. The arctic ice just the just gave up the ghost.

HARRIS: Melting did start a few weeks early, and a storm in early August also contributed to the ice loss. But a few decades ago, when the Arctic ice was thicker, those events wouldn't have led to such a dramatic melting. These days, Scambos says the ice is so thin it's easy to trigger a dramatic loss.

The loss of sea ice could affect weather patterns in the Northern Hemisphere, according Jennifer Francis at Rutgers University. And to her mind, the dramatic change in the Arctic drives home the point that climate change isn't just theoretical.

JENNIFER FRANCIS: Loss of the sea ice is just so conspicuous and so dramatic that it is something that, you know, even a first grader can look at in school and be able to understand that this is a tremendous change that's happening in a very short period of time.

HARRIS: And given the ongoing warming trend, summer melting is likely to become more pronounced in the coming years. James Overland at the National Oceanic and Atmospheric Administration says there is a little reassuring news, though.

JAMES OVERLAND: People for a while thought there would be a tipping point.

HARRIS: They worried that once ice melted to a certain extent, the Arctic would become permanently ice-free during the summertime, an irreversible change.

OVERLAND: That doesn't seem to be the case.

HARRIS: If we could stop global warming - a tall order, to be sure - the summer ice could eventually recover.

Richard Harris, NPR News.