Antarctic ice loss speeds up

NASA has charted a worrying trend in Antarctic ice levels, showing it is disappearing at an ever increasing rate that now rivals the loss of the Greenland ice sheet.

Over the past decade ice loss has increased by 75% say scientists from the US space programme and the University of California.

The researchers have analysed data from 1996 to 2006 and shown that the melt accounted for a rise in global sea levels of 0.3mm in ’96 to 0.5mm in 2006.

In terms of mass, that translates to a loss of 112 gigatonnes of ice in the first year of the period studied to a loss of 196 gigatonnes a decade later.

NASA’s Eric Rignot believes the losses are caused by ongoing and past acceleration of glaciers into the sea, mainly due to warmer oceans undermining the foundations of the ice sheet.

“Changes in Antarctic glacier flow are having a significant, if not dominant, impact on the mass balance of the Antarctic ice sheet,” he said.

Dr Rignot says the increased contribution of Antarctica to global sea level rise indicated by the study warrants closer monitoring.

“Our new results emphasize the vital importance of continuing to monitor Antarctica using a variety of remote sensing techniques to determine how this trend will continue and, in particular, of conducting more frequent and systematic surveys of changes in glacier flow using satellite radar interferometry,” he said.

“Large uncertainties remain in predicting Antarctica’s future contribution to sea level rise. Ice sheets are responding faster to climate warming than anticipated.”

Rignot said scientists are now observing these climate-driven changes over a significant fraction of the West Antarctic Ice Sheet, and the extent of the glacier ice losses is expected to keep rising in the years to come.

“Even in East Antarctica, where we find ice mass to be in near balance, ice loss is detected in its potentially unstable marine sectors, warranting closer study,” he said.

Academic organisations around the world, including the UK’s University of Bristol, are also involved in the research.

Sam Bond

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