Glacier melt causes large fraction of sea level rise

Thawing ice contributes nearly as much water to oceans as massive sheets at poles do

THAWING OUT  Melting of the world's glaciers (Argentina's Upsala Glacier, shown) contributed 29 percent of sea level rise from 2003 to 2009, a new analysis finds. 

Courtesy of Etienne Berthier

Melting glaciers around the world, discrete from the polar ice sheets, accounted for 29 percent of sea level rise from 2003 to 2009, scientists report in the May 17 Science. That’s almost as much sea level rise as the ice sheets themselves contributed during that time.

Glaciers, including those in Greenland and Antarctica that aren’t part of the ice sheets, lost 259 billion tons of ice per year, raising sea level 0.71 millimeters annually. Alex Gardner of Clark University in Worcester, Mass., and colleagues calculated the ice losses using satellite data and ground measurements of glaciers. Most of the melting occurred in Alaska, the Canadian Arctic, Greenland, the southern Andes and the Himalayas and other high mountains of Asia.

The team estimates that, together, the glacier and ice sheet losses explain 60 percent of sea level rise from 2003 to 2009. Other sources include expansion of the ocean as its waters warm.

Erin Wayman is the managing editor for print and longform content at Science News. She has a master’s degree in biological anthropology from the University of California, Davis and a master’s degree in science writing from Johns Hopkins University.

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