Recent summers on the vast, white expanse of the Greenland Ice Sheet have featured some spectacular ice melt, including an alarming period in 2012 when nearly the whole surface showed signs of melt. But this summer has instead seen several bouts of snow, staving off a big summer melt. So what gives?
While it may seem contradictory, those snows are actually something Greenland may see more of with global warming, as the atmosphere becomes primed to dump more heavy precipitation. And while that snow may insulate the ice sheet against major melt this year, focusing on one summer risks missing the forest for the trees. Because make no mistake, Greenland is still melting, dumping water into the ocean and causing global sea levels to steadily rise.
Several recent summers have seen particularly stark ice loss: At the peak of the 2012 melt season, about 97 percent of the ice sheet surface was melting — that melt season alone contributed 1 millimeter of global sea level rise. Last year, the melt season started two months early thanks to high temperatures across parts of the island.
But this year has been noticeably different. It all started in October, when big snowstorms “really loaded Greenland up,” Jason Box, a glaciologist at the Geological Survey of Denmark and Greenland, said. “That really preconditioned this year for low melt because it thermally insulates the darker ice below.”
While snowy weather may seem at odds with a warming world, Greenland could actually see more of it as temperatures rise. A warmer atmosphere can hold more moisture, which means that when storms pass through, they drop more precipitation. When temperatures are below freezing, as they are for much of Greenland through most of the year, that means more snowfall. (Rain has been falling at the expense of snow in the lower third of the island as temperatures rise above freezing, though.)