Nine months ago, NASA vividly made it clear that sea ice increases in Antarctica do not make up for the accelerated Arctic sea ice loss of the last decades, saying the planet has been shedding sea ice at an average annual rate of 13,500 square miles (35,000 square kilometers) since 1979, the equivalent of losing an area of sea ice larger than the state of Maryland every year.
“Even though Antarctic sea ice reached a new record maximum this past September, global sea ice is still decreasing,” said Claire Parkinson, author of the study and climate scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “That’s because the decreases in Arctic sea ice far exceed the increases in Antarctic sea ice.”
Now countering that argument, another study by NASA says that Antarctica is overall accumulating ice. The increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to offset the increased losses from its thinning glaciers, it said.
The latest research challenges the conclusions of even 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, although the net gain slowed down 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 Jay Zwally, a glaciologist with NASA Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study.
The paper was published in the Journal of Glaciology.
The study analyzed changes in the surface height of the Antarctic ice sheet measured by European Space Agency European Remote Sensing (ERS) satellites 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 has been accumulating over the last 10,000 years is thickening the ice by an average of 0.7 inches (1.7 centimeters) per year. Zwally’s team further calculated that the mass gain from the thickening of East Antarctica remained steady from 1992 to 2008 at 200 billion tons per year, while the ice losses from the coastal regions of West Antarctica and the Antarctic Peninsula increased by 65 billion tons per year.
“The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away,” Zwally said. “But this is also bad news. If the 0.27 millimeters 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.”