New Antarctic seabed sonar images reveal clues to sea-level rise

Published: Tuesday, May 5, 2009 - 08:43 in Earth & Climate

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British Antarctic Survey ship RRS James Clark Ross is equipped with sonar technology to map the seabed.
British Antarctic Survey

Motorway-sized troughs and channels carved into Antarctica's continental shelves by glaciers thousands of years ago could help scientists to predict future sea-level rise according to a report in the journal Geology this month (May). Using sonar technology from onboard ships, scientists from British Antarctic Survey (BAS) and the German Alfred Wegener Institute (AWI) captured the most extensive, continuous set of images of the seafloor around the Amundsen Sea embayment ever taken. This region is a major drain point of the West Antarctic Ice Sheet (WAIS) and considered by some scientists to be the most likely site for the initiation of major ice sheet collapse.

The sonar images reveal an 'imprint' of the Antarctic ice sheet as it was at the end of the last ice age around 10 thousand years ago. The extent of ice covering the continent was much larger than it is today. The seabed troughs and channels that are now exposed provide new clues about the speed and flow of the ice sheet. They indicate that the controlling mechanisms that move ice towards the coast and into the sea are more complex than previously thought.

Lead author Rob Larter from British Antarctic Survey said, "One of the greatest uncertainties for predicting future sea-level rise is Antarctica's likely contribution. It is very important for scientists and our society to understand fully how polar ice flows into the sea. Indeed, this issue was highlighted in 2007 by the Intergovernmental Panel on Climate Change (IPCC). Our research tells us more about how the ice sheet responded to warming at the end of the last ice age, and how processes at the ice sheet bed controlled its flow. This is a big step toward understanding of how the ice sheets are likely to respond to future warming.'

Source: British Antarctic Survey