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07/03/2013

Massive flooding causes ice crater beneath Antarctica

Antarctica

A file photo of a British Antarctic Survey's station. (Photo by Richard Burt) 

What happens in Antarctica does not necessarily stay in Antarctica.

Especially if it is flood water.

Just like lakes on the surface,  buried lakes under Antarctica’s ice cap can also let loose massive floods and one recent deluge sent as much water as is in Scotland’s Loch Ness flowing under the East Antarctic ice sheet, near the Cook Ice Shelf, say scientists. 

The flooding drained six billion tonnes of water, says a new study published in the journal Geophysical Research Letters.

It likely happened because a deeply-buried lake, about three kilomtres under the ice, suddenly over-topped. The peak discharge would have been more than double the normal flow rate of London’s River Thames.

Satellites were used to map the crater that developed as the ice-sheet slumped to fill the void left by the water.

Researchers are working to discover how these streams and floods affect the ice flow, especially as they try to predict how the continent shrounded in ice will respond to global warming. 

The crater covers an area of about 260 square kilometres and 70 metres deep at its lowest point. Authors of the study say the flooding happened over a period of about 18 months in 2007-2008.

“The crater is a big feature, Malcolm McMillan of the University of Leeds in England and lead author of the study, told the BBC.

The crater was detected and described using a combination of data gathered by the now-retired US Icesat mission and Europe’s new Cryosat platform, BBC reports .

The American spacecraft’s laser altimeter first noted a drop in the ice-surface height associated with the slumping. The European satellite’s radar altimeter was then employed to map the shape of the crater that resulted.

As many as 380 lakes have been discovered under Antarctica’s ice sheet, one with microbial life. Radar and seismic studies that can penetrate the thick ice have revealed complex waterways that feed and drain these lakes.

This flooding is believed to be the largest flooding under Antarctica.  

Raveena Aulakh is the Toronto Star's environment reporter. She is intrigued by climate change and its impact, now and long-term, and wildlife. Follow her on Twitter @raveenaaulakh

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