Ninety-seven per cent of surface ice covering Greenland melted in just four days in July, new Nasa data has revealed. The ice melted over a larger area than at any time in more than thirty years.
Nearly every part of the ice cover of Greenland experienced some melting of its surface between 8th and 12th July, according to measurements from three independent satellites analysed by NASA and scientists from the University of Georgia and City University of New York.
On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean.
Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.
– Son Nghiem, NASA
This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?
The melting spread quickly. Melt maps derived from the three satellites showed that on July 8, about 40% of the ice sheet's surface had melted. By 12th July, 97% had melted.
This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland's weather since the end of May.