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Monday, January 24, 2011

Um... Greenland's ice sheet melt in 2010 broke record

Um... Greenland's ice sheet melt in 2010 broke record

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I'm not a scientist, but I think the news that the Greenland ice sheet experienced record melt in 2010 should be on the front page across the country. But instead, that particular article from the Washington Post is relegated to a story in their "Post Carbon" blog.
The finding was announced in a paper, published Friday in Environmental Research Letters and described a combination of factors that brought about the record ice sheet melt last year.
"This past melt season was exceptional, with melting in some areas stretching up to 50 days longer than average," said Marco Tedesco, director of the Cryospheric Processes at the City College of New York, and the paper's lead author. "Melting in 2010 started exceptionally early at the end of April and ended quite late in mid- September."
Eight researchers from the U.S., Belgium, and the Netherlands co-wrote the paper, which examined the "albedo" effect on Greenland's ice sheet. White snow reflects more sunlight so less of the heat from the sun is absorbed and melts the ice sheet. With less snow, the "albedo" is less effective and ice melt is accelerated. The ice melt  in Greenland during 2010 was more than double the average yearly loss over the past three decades. The ice melt surpassed the record melt set in 2007 and every year since a 1996 benchmark.
In the paper, the researchers  wrote:
At Aasiaat… along Greenland's west coast, 2010 as a whole was the warmest since records began in 1951, with records also set for winter, spring, May and June. Narsarssuaq… in southern Greenland, saw its warmest winter and spring, its warmest May, and its warmest annual average since records began in 1951; Nuuk, the capital of Greenland, located along the southwest coast…, with a temperature time series extending back to 1873, saw record warmth for winter, spring, summer and the year as a whole.
Summer temperatures in Greenland during 2010 "were 3.0 °C (5.4 °F) above average," AFP reported. Last week, the National Oceanic and Atmospheric Administration (NOAA) announced that 2010 tied for the warmest year on record. On Thursday, the UN's World Meteorological Organization (WMO) announced that 2010 was the warmest year on record, so far. The top ten warmest years since 1850 have now all occurred since 1998.
In an email to the Post, Tedesco and "his colleagues estimate based on computer modeling that runoff in 2010 is 530 gigatons a year, compared to a 1958-2009 average of 274 gigatons a year and a 1979-2009 average of 285 gigatons a year."
With the ice melt increasing, the surface mass of the Greenland ice sheet is decreasing. The researchers wrote in their paper that they used Modèle Atmosphérique Régional (MAR), a regional climate model, because it allowed them to "examine conditions back to 1958, placing 2010 in the context of a longer time series." During the hydrological year, which is October 2009 through September 2010, the surface mass balance "set a new record low of -310 Gt [gigatonne], 2.6 standard deviations below the 1958-2009 average, surpassing the previous record of 2.3 standard deviations set in 2007."
With less ice sheet to keep the ice frozen, the melting may increase even more. If the variability was random, Tedesco explained to the International Business Times, "then over a 30-year period one would expect the record years to be evenly distributed -- they would be just as likely to be in 1970 as they are in 2001, but the data shows a gradual upward curve." The previous record-setting years were in 2005, 2002, and 1998. "Even the fact that the melt index was just about average in 2008 and 2009 doesn't alter the trend."
The melt season in Greenland started early, in mid-April, "after a warm and dry winter." A warm May 2010, up to 4 °C above the mean, "contributed to accelerated snowpack metamorphism and premature bare ice exposure, with the consequence of rapidly reducing the surface albedo." Less snow accumulation and "the positive albedo feedback mechanism are likely responsible for the premature exposure of bare ice."
Additionally, "summer snowfall, which helps to increase surface albedo, was below average" and the ice sheet melt during August and September was "also exceptional."
Tedesco said the primary concern is that the melting isn't linear. Double the amount of surface meltwater does not mean the ice sheet below is melting at the same rate.
More meltwater on the surface means more heat, which melts more ice and makes more meltwater. A river of water running over ice transfers heat to the ice because it is above freezing, melting yet more ice and increasing the volume of water. If the feedbacks accelerate past a certain point, the ice sheet will melt even faster, Tedesco said.
House Republicans are hellbent to "cut federal funding for international climate change initiatives", thePost reports. The Republican Study Committee budget plan released Thursday includes a provision to "eliminate taxpayer subsidies to the United Nations Intergovernmental Panel on Climate Change" which it says will produce a "$12.5 million annual savings."
NPR Science Friday reported that "scientists who study the oceans say the effects of climate change are already being seen in the world's oceans. From acidification and warming temperatures to sea-level rise and sea-ice loss." So, those savings could potentially result in the flooding of Miami, New Orleans, and Newark. But, that surely will be offset by the creation of new prime beachfront propertyin the U.S.

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