Glacial thinning has sharply accelerated at major South American icefields

Terra Daily via SPX: For the past four decades scientists have monitored the ebbs and flows of the icefields in the southernmost stretch of South America's vast Andes Mountains, detecting an overall loss of ice as the climate warms. A new study, however, finds that the rate of glacier thinning has increased by about half over the last dozen years in the Southern Patagonian Icefield, compared to the 30 years prior to 2000.

"Patagonia is kind of a poster child for rapidly changing glacier systems," said Michael Willis, lead author of the study and a research associate at Cornell University in Ithaca, New York. "We are characterizing a region that is supplying water to sea level at a big rate, compared to its size."

The Southern Patagonian Icefield together with its smaller northern neighbor, the Northern Patagonian Icefield, are the largest icefields in the southern hemisphere - excluding Antarctica. The new study shows that the icefields are losing ice faster since the turn of the century and contributing more to sea level rise than ever before.

Earlier studies determined that between the 1970's and 2000 both icefields, which feed into surrounding oceans as they melt, together raised global sea levels by an average of .042 millimeters each year. Since 2000, Willis and his colleagues found that number increased to 0.067 mm of sea level rise on average per year - about two percent of total annual sea level rise since 1998.

The Southern Icefield, which Willis and his colleagues focused on, loses around 20 billion tons (gigatonnes) of ice each year, the scientists calculated, which is roughly 9,000 times the volume of water stored by Hoover Dam annually....

Spegazzini Glacier in Parque Nacional Los Glaciares, Patagonia, Argentina. Shot by Luca Galuzzi (Lucag), Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license