Deep beneath the Antarctic ice sheet, floods of water from buried lakes can hurry glaciers along on their slow slide towards the sea, according to a new study that tracked recent floods beneath the Byrd Glacier. “It’s like putting in a squirt of oil,” says Andy Smith of the British Antarctic Survey, who was not involved in this latest study. “The water lubricates the base of the glacier” [New Scientist]. The findings will help researchers understand the movement of glaciers around the world, a matter of great interest to climate scientists who are investigating how rapidly ice sheets may melt into the ocean due to global warming.
Researchers discovered only recently that inaccessible subglacial lakes in Antarctica periodically shed huge quantities of water. Data collected by a satellite launched in 2003 … revealed a complex network of subglacial plumbing in which water periodically cascades from one hidden reservoir to another [AFP]. The water in the lakes remains liquid, despite being buried beneath a mile of ice in some places, due to warmth from the underlying rock. Now, researchers have shown that these hidden floods affect the thick mountains of ice above.
As reported in Nature Geoscience [subscription required], researchers measured the elevation of the ice in the Byrd Glacier by satellite. When the subglacial lakes fill up, they raise the elevation of the ice above them, and when the water spills over in a flood, the elevation sinks again, allowing researchers to track the water. Between December 2005 and February 2007 researchers saw rapid changes in the ice elevation that coincided with a marked increase in the speed of the ice flow. Conversely, the movement of the glacier slowed when the flood ceased and the lakes began to refill [New Scientist].
Researchers stressed that the floods beneath the Byrd Glacier were not caused by global warming: The lakes probably flood and drain on a regular basis that has nothing to do with atmospheric or ocean warming. However, the scientists say the mechanisms involved need to be understood so the knowledge can be applied to those ice masses which are being exposed to warmer temperatures, such as in Greenland [BBC News]. The International Panel on Climate Change (IPCC) has said that one of the great unknowns regarding climate change is what proporition of the world’s ice sheets will melt into the ocean, and how much that will raise sea levels.
Image: flickr / giladr