Melting mountain glaciers are pushing up sea level rises faster than at any time in the last 350 years, say scientists - indeed, many are melting up to 100 times faster.
A team from Aberystwyth University, the University of Exeter and Stockholm University surveyed the 270 largest outlet glaciers of the South and North Patagonian Icefields of South America.
Previous estimates of how much mountain glaciers contribute to sea-level rises have been 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," says lead author Professor Neil Glasser of Aberystwyth University.
"We took a different approach by using a new method that allows us to look at longer timescales. 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."
The team found that over the last 30 years, the glaciers have been losing volume ten to a hundred times faster than the 350-year long-term average.
"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 (c. AD 1750-1850)," says Dr Stephan Harrison of the University of Exeter.
"Our results show that recent (1990-2000) estimates of rates of glacier contribution to sea-level rise are well above the long-term (1650/1750-2010 and 1870-2010) average."