Antarctic subglacial lake causes colossal, localized flood

BBC : Over a period of about 18 months in 2007–08, an Antarctic subglacial lake discharged some 6 billion tons of water, presumably into the ocean. Scientists studying data gathered by NASA’s ICESat and Europe’s CryoSat-2 have determined that the huge flood occurred at the Cook subglacial lake in the eastern portion of the continent. They first detected a drop in the ice surface, which created a crater with an area of about 260 km² and a depth of about 70 m. From the shape of the crater, the researchers estimated the volume of water involved at some 6.4 km³, equivalent to the amount of water contained in Scotland’s Loch Ness. Antarctica contains some 400 subglacial lakes, kept liquid by heat from the rockbed below and ice pressure above. They may all be interconnected through a network of rivers. The system is quite complex, but it is thought that several lakes drain every year. “Whether all that water reaches the ocean or refreezes onto the underside of the ice—or even melts more ice with its heat—we just don’t know,” said team member Hugh Corr of the British Antarctic Survey.