Volume loss from Antarctic ice shelves is accelerating
The floating ice shelves surrounding the Antarctic Ice Sheet restrain the grounded ice-sheet flow. Thinning of an ice shelf reduces this effect, leading to an increase in ice discharge to the ocean. Using eighteen years of continuous satellite radar altimeter observations we have computed decadal-scale changes in ice-shelf thickness around the Antarctic continent. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 km3 per year for 1994-2003 to rapid loss of 310 ± 74 km3 per year for 2003-2012. West Antarctic losses increased by 70% in the last decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.
The floating parts of Antarctica's ice sheets have been thinning at increasing rates since the mid-1990s, raising fears of ice-sheet collapse and of accelerating sea-level rise in a warming climate.
Fernando Paolo of the Scripps Institution of Oceanography in San Diego, California, and his colleagues analysed an 18-year record of observations from three satellite radar missions. They found that the loss of ice-shelf volume increased from about 25 cubic kilometres a year in 1994–2003 to more than 300 cubic kilometres each year in 2003–2012.
This thinning has been most drastic in West Antarctica, where some floating shelves have lost almost one-fifth of their thickness in 18 years. If they continue to thin at current rates, these ice shelves will completely disappear within a century.
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