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Fast-melting glaciers puzzle scientists
(China Daily)
Updated: 2009-09-16 11:41 Climate deal needed In July, the world's oceans were the warmest in almost 130 years of record-keeping. Meteorologists say a combination of factors are at work, including a natural El Nino system, man-made global warming and a dash of random weather. Coinciding with the shrinking of sea ice on the North Pole and the thawing of the Arctic permafrost, the discovery of Greenland's runaway glaciers earlier this decade raised a sense of urgency among scientists studying the impact of climate change on the frozen north. It has also been used by advocacy groups like Greenpeace to stress the importance of reaching a deal in Copenhagen to limit global greenhouse emissions. The UN's top climate official, Yvo de Boer, said last week that negotiations on fighting climate change are moving so slowly that it will be impossible to reach a comprehensive deal by December. He said the Copenhagen meeting should aim instead to agree on "key cornerstones" of emissions cuts and how to finance them. Bracing for the worst Even a partial melt of the ice sheet could have a big impact on sea levels, with dire consequences for low-lying areas from Florida to Bangladesh.
"It doesn't sound like a lot, but it's an important difference by the way you sort of deal with that issue," says Hamilton, taking a break from his GPS measurements on a plateau overlooking Helheim's styrofoam-like bed of jagged ice. "How you engineer for a sea level rise of 30 centimeters is quite different as to how you would ... deal with a sea level rise of 1 meter." His latest measurements indicate that Helheim is flowing at 10.5 km (6.5 miles) per year, slightly down from its peak in 2005 but still 50 percent faster than its normal pace. Other researchers say some - but not all - of Greenland's glaciers have shown similar slowdowns in recent years, suggesting that a sudden, dramatic increase in flow speeds may not be such a cataclysmic and irregular phenomenon after all. Still, the flows remain fast enough to yield a net loss of mass from the ice sheet. And if the world continues to warm, sudden spurts of glacial acceleration may become more frequent, draining the inland ice until it, eventually, collapses. No one can say with certainty whether that will take 100 years, or 1,000. "It's a little embarrassing to know so little," says Ian Howat, a glaciologist based at Ohio State University. "We won't know it's going until it's gone. It feels like that a little bit." AP
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