NSIDC/Marc Serreze - Arctic Meltdown 20 Years Ahead Of Climate Models - 5C Warmer Over Melt Zones

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Though scientists tend to agree that summer ice at the North Pole will eventually disappear, they haven't settled on a date. And one group now claims to have evidence that Santa may have to start swimming much sooner than we thought. US researchers claim to have found evidence that accelerated melting has crossed a "tipping point" from which there is no going back.

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During the summer, as ice melts, it is replaced by dark ocean waters that absorb heat. When the cooler winter weather arrives, the oceans release this warmth, creating a pocket of higher temperatures above the Arctic that slows down the regrowth of sea ice during the winter. By measuring the air temperature directly over the Arctic after the end of the summer melt, Serreze found a large amount of released heat. Temperatures in areas losing ice were as much as 5 °C higher over the last four years as compared to the historic average.

The computer models predict this "Arctic acceleration," says Serreze but 20 years into the future. "The models are giving us the big picture of what is going on, but it's all happening much faster than expected," he says. This change may already be irreversible, as the extra heat creates a runaway thinning of ice that will soon be unable to survive in the summer Sun. If it disappears entirely during the summers, the ramifications would be global.

"The Arctic is the heat sink of the Northern hemisphere; the circulation patterns of the oceans could change dramatically," says Serreze. What's more, the effects from this rush of heat seem to already be bleeding out into neighbouring Alaska and Siberia.

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http://www.newscientist.com/article/dn16307-arctic-melt-20-years-ahead-of-climate-models.html?DCMP=OTC-rss&nsref=climate-change