Antarctic ice sheet warming faster than thought

The West Antarctic Ice Sheet, whose melt may be responsible for 10 percent of the sea-level rise caused by climate change, is warming twice as quickly as previously thought, a study said Sunday. A re-analysis of temperature records from 1958 to 2010 revealed an increase of 2.4 degrees Celsius (36.3 degrees Fahrenheit) over the period — three times the average global rise. The increase was nearly double what previous research had suggested, and meant this was one of the fastest-warming regions on Earth, according to paper co-author David Bromwich of the Byrd Polar Research Center.   “Our record suggests that continued summer warming in West Antarctica could upset the surface balance of the ice sheet, so that the region could make an even bigger contribution to sea-level rise than it already does,” he said. Scientists believe the shrinking of the West Antarctic Ice Sheet is responsible for about 10 percent of global warming-related sea-level rise, which if unchecked threatens to flood many coastal cities within a few generations. The sheet, a huge mass of ice up to four kilometres (2.5 miles) thick that covers the land surface and stretches into the sea, is melting faster than any other part of Antarctica. Data records kept at Byrd Station in the central West Antarctic had been incomplete. Since being established in 1957, the research station has not been consistently occupied and has seen frequent power outages, especially during the long polar night, when its solar panels cannot recharge. Bromwich and a team from several US-based research institutions used weather data from different sources to plug holes in the Byrd data and corrected calibration errors.     The updated log was published in the journal Nature Geoscience. “Aside from offering a more complete picture of warming in West Antarctica, the study suggests that if this warming trend continues, melting will become more extensive in the region in the future,” said Bromwich. The UN Intergovernmental Panel on Climate Change in 2007 had projected sea level rise of 18 to 59 centimetres (seven to 23 inches) worldwide by the year 2100. But a study by the US National Research Council said in June the actual rise could be two to three times higher, with polar ice-cap melt speeding up the process.