Major melt reveals details about Greenland ice sheet

Los Angeles Times : In the span of a few days in 2012, nearly the entire surface layer of Greenland’s 20 000 mi² (32 000 km²) ice sheet melted. Some of the water was absorbed directly into the snow and the rest of it formed rivers. Laurence C. Smith of UCLA and his colleagues were in Greenland at the time and used GPS trackers, drones, and satellite images to monitor the rivers. They found that most of the rivers led deep below the surface through holes in the ice sheet called moulins. They compared the surface flow with the flow at the edge of the ice sheet into the Isortoq River and found that about one quarter of the water remains well below the surface. Therefore, researchers will need to adjust climate models that assume that all the melt water reaches the ocean. The finding also raises questions about how the water is being absorbed into the ice sheet and what effect it is having on the ice itself.