Ice Sheet was the worst ever recorded, according to research from the City College of New York.
"This past melt season was exceptional, with melting in some areas stretching up to 50 days longer than average," said Dr Marco Tedesco, director of the CCNY's Cryospheric Processes Laboratory.
"Melting in 2010 started exceptionally early at the end of April and ended quite late in mid- September."
The study examined surface temperature data over the Greenland ice sheet surface, as well as estimates of surface melting from satellite data, ground observations and models.
The team says that in 2010, summer temperatures up to 3C above the average were combined with reduced snowfall. The capital of Greenland, Nuuk, had the warmest spring and summer since records began in 1873.
Bare ice was exposed earlier than average, and for longer than inprevious years, contributing to the extreme record.
"Bare ice is much darker than snow and absorbs more ," said Professor 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."
World Wildlife Fund climate specialist Dr Martin Sommerkorn said that the melting will form a significant part of projected sea level rises over the coming decades.
"Sea level rise is expected to top 1 metre by 2100, largely due to melting from ice sheets," he said. "And it will not stop there – the longer we take to limit greenhouse gas production, the more melting and water level rise will continue."