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November 23, 2009 – Original Source: Climate Feedback, Nature Magazine

Daniel Cressey; cross-posted from The Great Beyond

The ice sheet covering east Antarctica may have been melting since 2006, according to new research, contradicting previous suggestions that it has remained stable or even grown in mass.

Using measurements for 2002 to 2009 from a twin pair of satellites, researchers at the University of Texas at Austin in Austin, Texas, say east Antarctica is losing mass at about 58 gigatonnes a year. Most of the loss appears to be from coastal regions and to stem from increased ice loss post 2006.

Previous studies have generally used satellites to measure elevation or movement of ice. The new study – published in Nature Geoscience – instead looks at the Earth’s gravity field and uses that to work out how much ice is there. It also suggests that 132 Gt of the total annual ice loss of 190 Gt per year is coming from the west.

Although there are uncertainties in the data, the new estimates of ice loss are on average consistent with previous calculations, “but, in contrast to previous estimates, they indicate that as a whole, Antarctica may soon be contributing significantly more to global sea-level rise”, the researchers write in their paper.

The finding is significant because the east of the continent has traditionally been seen as the more stable half. It is also the bigger half so if it is melting it could contribute more to sea level rise.

“We felt surprised to see this change in east Antarctica,” says study author Jianli Chen (BBC, Guardian). “If the current trend continues or gets worse, Antarctica could become the largest contributor to sea level rises in the world. It could start to lose more ice than Greenland within a few years.”

Jonathan Bamber, of the University of Bristol, told Bloomberg he was also surprised, as those previous studies have suggested the East Antarctic Ice Sheet really wasn’t changing that much. “This result really confirms that there are very substantial inconsistencies between different estimates,” he says. “The margins of error are so large that it can be difficult to draw strong conclusions.”


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