Antarctic ice loss may raise global sea level: study

Loss of ice in Antarctica caused by a warming ocean could raise global sea levels by three metres, a new study has warned.
Researchers from the University of Edinburgh and University of Northumbria in the UK assessed the landscape to determine how the West Antarctic ice sheet might respond to increasing global temperatures.
In the first study of its kind, researchers were able to gauge how levels of ice covering the land have changed over hundreds of thousands of years.
They did so by studying peaks protruding through ice in the Ellsworth Mountains, on the Atlantic flank of Antarctica.
Researchers assessed changes on slopes at various heights on the mountainside, which indicate levels previously reached by the ice sheet.

They also mapped the distribution of boulders on the mountainside, which were deposited by melting glaciers.

Chemical technology - known as exposure dating - showed how long rocks had been exposed to the atmosphere, and their age.
The results indicate that during previous warm periods, a substantial amount of ice would have been lost from the West Antarctic ice sheet by ocean melting, but it would not have melted entirely.
This suggests that ice would have been lost from areas below sea level, but not on upland areas.
The study shows that parts of the West Antarctic ice sheet have existed continuously for at least 1.4 million years.

"Our findings narrow the margin of uncertainty around the likely impact of the West Antarctic Ice Sheet on sea level rise," said Andrew Hein from University of Edinburgh.
"This remains a troubling forecast since all signs suggest the ice from West Antarctica could disappear relatively quickly," Hein said.
"It is possible that the ice sheet has passed the point of no return and, if so, the big question is how much will go and how much will sea levels rise," added John Woodward from the University of Northumbria.
The findings were published in the journal Nature Communications.