Credit: Photo courtesy Michael Studinger/NASA

Greenland experienced unprecedented ice loss in 2010, with surface melting reaching its highest level since records began in 1979, according to results from modelling studies. Although air temperature was a factor, snowfall and albedo — a measure of the amount of light reflected from the ice surface — probably played a key role in altering the mass balance of the giant ice sheet.

Marco Tedesco from the City College of New York and co-workers analysed remote-sensing data, observations of the ice-sheet surface and output from a regional atmospheric model to investigate the key factors influencing surface mass balance on Greenland during 20101. The results suggest that bare ice became exposed very early in the season due to a relatively warm, dry winter and temperatures 4 °C above average during May. As a result, ice was exposed four times longer than during a typical year. Compared with fresh snow, bare ice has a lower albedo, which increases the amount of sunlight absorbed and enhances melt. Furthermore, below-average snowfall further reduced the albedo and increased melting.

The unusually high ice loss during 2010 was partly due to high pressure that persisted over the region from late spring and throughout summer.