The massive west Antarctic ice sheet, previously assumed to be stable, is starting to collapse, scientists warned on Tuesday.
Antarctica contains more than 90% of the world's ice, and the loss of any significant part of it would cause a substantial sea level rise. Scientists used to view Antarctica as a "slumbering giant", said Chris Rapley, from the British Antarctic Survey, but now he sees it as an "awakened giant".
Rapley presented measurements of the ice sheet at a major climate conference in Exeter, UK. Glaciers on the Antarctic peninsula, which protrudes from the continent to the north, were already known to be retreating. But the data Rapley presented show that glaciers within the much larger west Antarctic Ice sheet are also starting to disappear.
If the ice on the peninsula melts entirely it will raise global sea levels by 0.3 metres, and the west Antarctic ice sheet contains enough water to contribute metres more. The last report of the Intergovernmental Panel on Climate Change, published in 2001, said that collapse of this ice sheet was unlikely during the 21st century. That may now need to be reassessed, Rapley warned.
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