Greenlands lurking aquifer

摘要

At intermediate elevations along the flanks of the Greenland ice sheet, strong surface melting can occur during summer months. Nevertheless, over the course of a year more snow falls than melts. As snow layers are buried by the accumulating snowfall, they compact and densify. Eventually the snow turns to firn, which can extend up to 100 metres in depth before fully transforming into glacial ice. An important source of uncertainty in determining Greenland’s runoff — and how it might change in the future — has been in understanding how much of the melt water from firn-covered regions is partitioned into runoff, and how much is left behind in the ice sheet after infiltrating into underlying firn and refreezing. Writing in Nature Geoscience, Forster and colleagues1 document direct evidence for a massive aquifer in firn that stores melt water yearround beneath the surface of the ice sheet in southern Greenland.