The ice sheet covering Greenland melted at the fastest rate since records began in 1979, a new study shows. That’s important because the ice sheet is becoming a major contributor to projected sea level rises in coming decades.
"This past melt season was exceptional, with melting in some areas stretching up to 50 days longer than average," said study co-author Marco Tedesco, director of the Cryospheric Processes Laboratory at The City College of New York.
"Melting in 2010 started exceptionally early at the end of April and ended quite late in mid- September," he added in a statement released with the study.
"Over the past 30 years, the area subject to melting in Greenland has been increasing" at about 17,000 square kilometers a year, Tedesco stated on his research website.
"This is equivalent to adding a melt-region the size of Washington state every ten years," he added. "Or, in alternative, this means that an area of the size of France melted in 2010 which was not melting in 1979."
In the study published in "Environmental Research Letters," the researchers also said that Greenland's summer temperatures last year were up to 3 degrees Centigrade above the average and that the ice sheet saw reduced snowfall.
Nuuk, the capital of Greenland, had the warmest spring and summer since records began in 1873.
Because of the diminished snowfall, bare ice was exposed earlier than average and longer than in previous years, contributing to the extreme record.
"Bare ice is much darker than snow and absorbs more solar radiation," said Tedesco. "Other ice melting feedback loops that we are examining include the impact of lakes on the glacial surface, of dust and soot deposited over the ice sheet and how surface meltwater affects the flow of the ice toward the ocean."
The researchers analyzed satellite and land surface data.
The current contribution of Greenland ice melt to global sea level rise is about .02 inches a year, but the potential impact is enormous.
About a quarter the size of the United States, Greenland has about one-twentieth of the world's ice — the equivalent of about 21 feet of global sea rise were it to completely melt into the sea.
That process could take centuries to complete, but once started would be difficult to reverse.