Antarctica's hidden plumbing revealed

09-14-2009 • New Scientist

THE first complete map of the lakes beneath Antarctica's ice sheets reveals the continent's secret water network is far more dynamic than we thought. This could be acting as a powerful lubricant beneath glaciers, contributing to sea level rise. Unlike previous lake maps, which are confined to small regions, Ian Joughin at the University of Washington in Seattle and colleagues mapped 124 subglacial lakes across Antarctica using lasers on NASA's ICESat satellite (see map). The team also observed the lakes draining and filling. While interior lakes tended to be static, many coastal lakes changed significantly. Some even appear to be connected by channels under the ice hundreds of kilometres long. For instance, when upstream lakes under the Recovery glacier drained 3 cubic kilometres of water, lakes downstream gained a similar amount (Journal of Glaciology, vol 55, p 573). Water flowing under glaciers can act as a lubricant, causing land ice to accelerate into the sea and add to rising sea levels. "The implications for the flow of ice are potentially quite significant," says Andy Smith of the British Antarctic Survey in Cambridge, UK. Those lakes with no clear drainage channels are of particular interest, he says, because they could be spreading a thin film of lubricating water under glaciers.