April 4, 2011

Chile’s Glaciers Melting Fast

New research, published Sunday in the journal Nature Geoscience, highlights San Rafael Glacier in Patagonia, which has retreated about 5 miles since the peak of the Little Ice Age, BBC News reports.

Glaciers have lost volume on average "10 to 100 times faster" in the last 30 years.

Sea levels are rising faster now than at any time in the last 350 years and melting glaciers are a large reason for that, according to the study by Universities at Aberystwyth, Exeter and Stockholm who looked at longer timescales than usual.

The northern ice field on the San Rafael Glacier extends for nearly 125 miles, covering a surface of 2,600 square miles, while the southern ice field is more than 217 miles long, covering 8,000 square miles.

The scientists mapped changes in the position of the glaciers since the Little Ice Age, which happened around 1870 for the north ice field and around 1650 for the southern ice field.

"Previous estimates of sea-level contribution from mountain glaciers are based on very short timescales. They cover only the last 30 years or so when satellite images can be used to calculate rates of glacier volume change," lead author, Professor Neil Glasser of Aberystwyth University explained.

"We took a different approach by using a new method that allows us to look at longer timescales," Glasser continued. The survey centered on remotely sensed images of outlet glaciers of the south and north Patagonian ice fields using longer timescales than previous studies.

"We knew that glaciers in South America were much bigger during the Little Ice Age so we mapped the extent of the glaciers at that time and calculated how much ice has been lost by the retreat and thinning of the glaciers," Glasser concluded. Calculations showed the mountain glaciers in recent years have increased their melt rate rapidly and thus their contribution to global sea level.

Dr. Stephen Harrison of the University of Exeter, added: "The work is significant because it is the first time anyone has made a direct estimate of the sea-level contribution from glaciers since the peak of the industrial revolution (between 1750-1850)." Results "well above" the long-term averages, which cover 1650/1750 to 2010 and 1870-2010.


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