By Annie Sneed
Climate change is warming the Arctic more than twice as fast as anywhere else on the planet. One of the most serious consequences is sea level rise, which threatens nations from Bangladesh to the U.S. But exactly how does melting Arctic ice contribute to sea level rise? Scientific American asked Eric Rignot, professor of earth system science at the University of California, Irvine, and Andrea Dutton, assistant professor of geology at the University of Florida, how changes in this particular northern region are driving the oceans to dangerous heights.
Seas are now rising an average of 3.2 millimeters per year globally, and are predicted to climb a total of 0.2 to 2.0 meters by 2100. Rignot and Dutton say that in the Arctic, the Greenland Ice Sheet poses the greatest risk for ocean levels because melting land ice is the main cause of rising seas—and “most of the Arctic’s land ice is locked up in Greenland,” Rignot explains. That’s 2.96 million cubic kilometers of ice now covering land areas—and it’s melting into the ocean. If the entire Greenland Ice Sheet thawed, Dutton says, it would raise sea levels by an average of seven meters. That would significantly flood coastal megacities such as Mumbai and Hong Kong.
Greenland’s land ice is already thawing fast enough to raise worldwide seas 0.74 millimeter per year. “The melt rate has been increasing,” in large part because the ice sheet’s surface thawing has picked up as global temperatures warm, Dutton says. “This acceleration of surface melt has doubled Greenland’s contribution to sea level rise” compared with the period from 1992 to 2011, Dutton adds.
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