Nature Geoscience Study Projects Greenland Deep Waters To Warm At 2X Global Rate - Up To 2C

Scientists have uncovered a potentially potent risk to Greenland’s ice sheets during the next century and beyond: rapidly warming deep water. The subsurface ocean off Greenland is now expected to warm at roughly double the rate that is projected for such waters globally, including off the coast of Antarctica.

Calling the ocean “the 900-pound gorilla of global warming and climate change,” oceanographer Josh Willis of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., says he’s excited to finally see long-term climate projections homing in on the ocean’s role. “How the oceans affect the great ice sheets in Greenland and Antarctica could mean the difference between getting two feet and six feet of sea level rise in the coming century,” observes Willis, who had no role in the new analysis. “So this is a big deal.”

Until now, “no one had noticed that the ocean surrounding Greenland and Antarctica will warm very differently during this century and the next,” says climate modeler Jianjun Yin of the University of Arizona in Tucson, who led the new study, published online July 3 in Nature Geoscience. Although his group’s conclusions come from computer analyses, Yin notes that the study’s projections “are quite consistent with recent observations of subsurface ocean temperatures around Greenland.”

Yin’s team ran 19 computer programs to project the effects of global climate change on the world’s great bodies of water, many for periods through 2200. These analyses consistently turned up surprises, Jin says, including signs of substantial warming during the next 90 years and beyond in waters off Greenland at depths of 200 to 500 meters. The increase, projected to total about 2° Celsius, could erode the base of glaciers in fjords, where the ice can reach as deep as 1,000 meters below the ocean surface. And unlike the glacial surface, which remains frozen in winter, the deeply submerged portions of tidal glaciers can melt year-round, Yin says, greatly accelerating their underwater calving.

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http://www.sciencenews.org/view/generic/id/332165/title/Greenland%E2%80%99s_ice_sheets_face_new_threat