By Maggie Fox
Washington - It may be dropping huge chunks of iceberg that drift hundreds of kilometres while they slowly melt, but the West Antarctic Ice Sheet just may have stopped melting, scientists reported on Thursday.
Their study, published in Friday's issue of the journal Science, is sure to provoke controversy and will have to be confirmed by other experts.
But the team at Nasa's Jet Propulsion Laboratory and the California Institute of Technology say their measurements show the ice sheet is getting thicker.
Difficult to measure "We find strong evidence for ice-sheet growth," Ian Joughlin and Slawek Tulaczyk wrote in their report.
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Joughlin and many others have been taking measurements that show the ice sheet, known to scientists as the WAIS, has been steadily melting since the end of the last Ice Age about 11 000 years ago. It currently covers about 930 000 sq km.
The sheet has enough ice to raise global sea levels by 1,5 to 5,5 metres if it all melted. Earlier predictions had said that it could melt in 4 000 years.
The United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC) predicts the average global temperature could be as much as 6 degrees C higher at the end of the century than it was in 1990. If this affected the Antarctic, it could melt enough ice to raise sea levels enough to swamp coastal areas.
It would also greatly alter the planet's climate by changing ocean currents and temperatures.
But experts have been saying there is little evidence that global warming is responsible for melting the ice sheet - they say currents and the way water washes underneath the floating portions seems to have more of an effect.
Joughlin and Tulaczyk used satellite radar to measure the thickness of the ice.
They specifically looked at ice streams, which are similar to large, flowing rivers of ice.
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