Antarctica gaining more ice than it's losing: NASA

Chennai

Washington: The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change's (IPCC) 2013 report, which says that Antarctica is overall losing land ice. According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.

"We're essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica," said lead author Jay Zwally, a glaciologist with NASA Goddard Space Flight Centre in US.

"Our main disagreement is for East Antarctica and the interior of West Antarctica - there, we see an ice gain that exceeds the losses in the other areas," said Zwally.

But it might only take a few decades for Antarctica's growth to reverse, according to Zwally.

"If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they've been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years," Zwally said.

The study analysed changes in the surface height of the Antarctic ice sheet measured by radar altimeters on two European Space Agency European Remote Sensing (ERS) satellites, spanning from 1992 to 2001, and by the laser altimeter on NASA's Ice, Cloud, and land Elevation Satellite (ICESat) from 2003 to 2008.

The extra snowfall that began 10,000 years ago has been slowly accumulating on the ice sheet and compacting into solid ice over millennia, thickening the ice in East Antarctica and the interior of West Antarctica by an average of 1.7 centimetres per year.

This small thickening, sustained over thousands of years and spread over the vast expanse of these sectors of Antarctica, corresponds to a very large gain of ice - enough to outweigh the losses from fast-flowing glaciers in other parts of the continent and reduce global sea level rise.

"The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimetres per year away," Zwally said.

"But this is also bad news. If the 0.27 millimetres per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for," Zwally said.

The study was published in the Journal of Glaciology.