In mid-July, 97 percent of the surface of Greenland’s ice sheet was melting, according to analyses performed by NASA and other climate scientists. Normally about half of the ice sheet surface thaws during a summer season. The high degree of melt this year is attributed to a series of unusually strong ridges of warm air, or heat domes, hovering over the country. Because much of the melt refroze within a few days, its contribution to sea-level rise is believed to be little.
Geological records suggest that in the past the ice sheet has experienced similar melting about every 150 years. But by the first week of August the cumulative melt had already exceeded the previous record, with extended thawing occurring at high elevations. While this year’s events are consistent with predictions made through climate change modeling, the surprise is the speed at which they are taking place. According to a recent study, even if Greenland avoids record high temperatures, persistent warmth can amplify melting and an albedo feedback loop that accelerates ice loss.