Paris–Greenland's ice sheet, feared as a major driver of rising sea levels, shed a record amount of melted snow and ice in 2010, scientists reported Friday, a day after the UN said last year was the warmest on record.
The 2010 runoff was more than twice the average annual loss in Greenland over the previous three decades, surpassing a record set in 2007, said the study, published in the US-based journal Environmental Research Letters.
Ice melt has now topped this benchmark every year since 1996, according to the paper, derived from long-term satellite and observational data.
Were it to melt entirely, Greenland's ice sheet would drive up ocean levels by some seven meters (23 feet), drowning coastal cities around the world.
No credible projections today include a doomsday scenario for the coming centuries. But recent research, including the new study, suggest that Greenland will contribute more to rising seas than predicted only a few years ago.
Based on computer models, Tedesco estimated that runoff in 2010 was 530 gigatons, or billions of tons, compared to an average of 274 gigatons for the period 1958-2009, and 285 gigatons for 1979-2009.
"The process is far from being linear, and it is not possible to simply draw a line" into the future, said lead researcher Marco Tedesco, who heads the Cryosphere Processes Laboratory at the City College of New York.
But over the last 30 years "there has been an increase in runoff," he said in an email exchange.
Researchers have thrown up different figures for how much, and how fast, Greenland is shedding its icy mantle, which is up to three kilometers (1.7 miles) thick in places.
They concur, though, that climate change is largely to blame: temperatures in the Arctic region have risen at two to three times the global average over the last 40 years.
In Greenland, summer temperatures in 2010 were 3.0 degrees Celsius (5.4 degrees Fahrenheit) above average.
"The capital, Nuuk, had the warmest spring and summer since records began in 1873," Tedesco noted.
Globally, the year was also the warmest ever recorded, as was the decade it brought to a close, the UN's World Meteorological Organization (WMO) said on Thursday.
The new study focused on surface melt, runoff and the number of days when bare ice, free of snow, is exposed to the Sun's melting rays.