In DepthGeophysics

Polar scientists to peer beneath largest ice shelf

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Science  05 Jun 2015:
Vol. 348, Issue 6239, pp. 1070-1071
DOI: 10.1126/science.348.6239.1070

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The Ross Ice Shelf, a thick, floating tongue of solid ice the size of Spain, is the biggest of the many such barriers that ring Antarctica and keep its ice sheets from sliding into the sea. Yet the shape of the sea floor beneath—a critical factor in how fast the shelf might melt—is virtually unknown. The ice keeps sonar-carrying ships out, and the water beneath it blocks radar. Now, geophysicists at Columbia University“s Lamont-Doherty Earth Observatory in Palisades, New York, plan to fill in the giant blank spot, using an ultrasensitive airborne gravity detector. The sensor detects tiny changes in gravity: the boosts caused by the extra mass of seafloor hills and the decreases from troughs. The team plans to crisscross the Ross shelf in 36 flights over two 3-week-long campaigns, one in November and a second in 2016. They hope to map features as small as 50 meters tall—dramatically better than the present map, which scientists pieced together in the 1970s by setting off small explosions on the ice every 50 kilometers and recording the echoes.