Friday, March 30, 2012

Study of Patagonian glacier's rise and fall adds to understanding of global climate change

Alpha Galileo via the University of Ghent: Glaciers play a vital role in Earth’s climate system, and it’s critical to understand what contributes to their fluctuation.

Increased global temperatures are frequently viewed as the cause of glacial melt, but a new study of Patagonia’s Gualas Glacier highlights the role of precipitation in the glacier’s fluctuation. The study, conducted by Sébastien Bertrand of Renard Centre of Marine Geology, Ghent University (Belgium) and Woods Hole Oceanographic Institution (WHOI) and his colleagues, reconstructs a 5,400 year-record of the region’s glacial environment and climate, comparing past temperature and rainfall data with sediment records of glacier fluctuations and the historical observations of early Spanish explorers.

The study, “Precipitation as the main driver of Neoglacial fluctuations of Gualas Glacier, Northern Patagonian Icefield,” was published March 15 in the Open Access journal Climate of the Past.

As glaciers fluctuate, retreating or adding mass, they dramatically affect the water cycle -- locking up fresh water as they amass, causing the sea level to rise as they thaw and retreat.

“Improving our understanding of the impact of climate changes on glacier variability is one of the most pressing aspects of present-day climate research,” says Bertrand, a postdoctoral fellow in WHOI’s Marine Chemistry and Geochemistry department and the Renard Centre of Marine Geology, University of Ghent.

The focus of the work is Gualas Glacier, a 32-kilometer long shifting mountain of ice with an area of 119.2 square kilometers that sits above Golfo Elefantes. It is part of the Northern Patagonian Icefield (NPI), a series of 70 glaciers fed by precipitation that originates in the Pacific Ocean and falls in the rain belt west of the Andes, reaching levels of up to ten meters a year. The majority of the western NPI glaciers have retreated over the last 150 years.

“These glaciers are retreating as a response to global climate change, but not only because of increasing temperature, which is generally cited as the cause of worldwide glacier retreat,” said Bertrand. “The fast retreat of Gualas, and other western NPI glaciers, during the last century, seems to be driven by a decrease in winter precipitation -- snow -- rather than by an increase in temperature.”...

Amalia Glacier, South Patagonia, Chile, shot by Gus1234wiki, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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