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Antarctica shedding ice faster today than ten years ago

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Investigators from five countries, led by Eric Rignot of NASA's fabled Jet Propulsion Laboratory (JPL), used interferometry radar from four satellites to build a picture of the periphery of Antarctica.

They sought to measure the velocities of glaciers that shift ice to the coast from the massive sheets that cover Antarctica's bedrock. They built up a picture of around 85 per cent of Antarctica's coastline thanks to the data supplied by the European Space Agency's two Earth Remoting Sensing (ERS) satellites, the Canadian Radarsat-1 and Japan's Advanced Land Observing satellites.


"Most of the mass loss is from the Pine Island Bay sector of West Antarctica and the northern tip of the Peninsula, where it is driven by ongoing, pronounced glacier acceleration. Pine Island Bay host the two largest dischargers of ice in Antarctica, Pine Island Glacier and Thwaites Glacier.


"Over the time period of our survey, the ice sheet as a whole was certainly losing mass, and the mass loss increased by 75 percent in 10 years," according to the study, published online by the specialist journal Nature Geoscience.



Recent Antarctic ice mass loss from radar interferometry and regional climate modelling


Large uncertainties remain in the current and future contribution to sea level rise from Antarctica. Climate warming may increase snowfall in the continent's interior1, 2, 3, but enhance glacier discharge at the coast where warmer air and ocean temperatures erode the buttressing ice shelves4, 5, 6, 7, 8, 9, 10, 11. Here, we use satellite interferometric synthetic-aperture radar observations from 1992 to 2006 covering 85% of Antarctica's coastline to estimate the total mass flux into the ocean. We compare the mass fluxes from large drainage basin units with interior snow accumulation calculated from a regional atmospheric climate model for 1980 to 2004. In East Antarctica, small glacier losses in Wilkes Land and glacier gains at the mouths of the Filchner and Ross ice shelves combine to a near-zero loss of 461 Gt yr-1. In West Antarctica, widespread losses along the Bellingshausen and Amundsen seas increased the ice sheet loss by 59% in 10 years to reach 13260 Gt yr-1 in 2006. In the Peninsula, losses increased by 140% to reach 6046 Gt yr-1 in 2006. Losses are concentrated along narrow channels occupied by outlet glaciers and are caused by ongoing and past glacier acceleration. Changes in glacier flow therefore have a significant, if not dominant impact on ice sheet mass balance.


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University of California Irvine, Earth System Science, Irvine, California 92697, USA

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA

Centro de Estudios Cientificos, Arturo Prat 514, Valdivia, Chile

University of Bristol, Bristol BS8 1SS, UK

Institute for Marine and Atmospheric Research (IMAU), Utrecht University, 3584 CC Utrecht, The Netherlands

University of Missouri-Columbia, Columbia, Missouri 65211, USA

Royal Netherlands Meteorological Institute (KNMI), 3732 GK De Bilt, The Netherlands

Correspondence to: Eric Rignot1,2,3 e-mail: erignot@uci.edu






In the worst-case scenario, (1) the Amundsen Sea sector of the West Antarctic Ice Sheet collapses into Pine Island Bay, (2) this causes the ice divide in that sector to migrate inland, (3) which shrinks the accumulation areas of West Antarctic ice streams entering Ronne Ice Shelf and Ross Ice Shelf, (4) thereby causing retreat of these ice-shelf grounding lines, (4) steeping the surface slopes of Foundation Ice Stream and of Ice Stream A, Ice Ridge AB, and Ice Stream B, (5) increasing discharge of East Antarctic ice through the Bottleneck into these ice streams, (6) enlarging the East Antarctic ice-drainage basins of these ice streams, (7) increasing the overall discharge of East Antarctic ice into West Antarctica, (8) shrinking the accumulations area of East Antarctic ice that is now discharged into the Indian Ocean, (9) thereby imparting a negative shift in the mass balance of East Antarctic ice streams discharging into the Indian Ocean, (10) initiating grounding-line retreat of these ice streams, (11) which accelerates the volume of ice discharged by these ice streams, and (12) causes an increase in sea level from East Antarctic ice that is added to the increase from collapsing West Antarctic ice.



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