A recent study by NASA has shown that an increase in atmospheric precipitation, in the form of snowfall, is currently adding enough ice to outweigh the losses from thinning glaciers.
The Intergovernmental Panel on Climate Change’s (IPCC) 2013 report claimed there is an overall losing of land ice, but new satellite data challenges the study and suggests the situation may be more complex than originally thought.
“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 Jay Zwally, a glaciologist from the NASA Goddard Space Flight Center in Greenbelt, Maryland.
Radar altimeter data on two European Space Agency European Remote Sensing (ERS) satellites and NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) have shown that there was a net gain of 112 billion tons of ice a year from 1992-2001, which then slowed to 82 billion tons from 2003-2008.
Scientists are able to calculate the increase or decrease of ice by the surface height measured by the satellite altimeters. NASA explains that if the amount of snowfall accumulation in a location is not equal to the ice flow downward or toward the ocean, there will be a change in surface height. The ice-sheet will grow if the snowfall accumulation is greater than the ice flow.
NASA reports that the increase of snowfall accumulation over the past 10,000 years is related to the warming of the air. The snow compacts to ice and, as a result, ice sheets in East Antarctica and the West Interior of Antarctica have been thickening by about 0.7 inches per year.
“At the end of the last Ice Age, the air became warmer and carried more moisture across the continent, doubling the amount of snow dropped on the ice sheet,” Zwally said.
Zwally explains that the growing of Antarctica means it is not actually contributing to sea level rise; Antarctica is reducing the sea level by 0.23 mm every year. This is good news. However, it does pose some important questions for scientists and climatologists.
“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,” Zwally said.
Even if this is the case, it does not necessarily mean Antarctica won’t contribute to sea level rise in the future.
It will only take 20-30 years before the losses in West Antarctica and the Antarctic Peninsula will catch up to the current gain. As long as losses continue to increase at their current rate, Zwally does not believe there will be enough snowfall to offset the losses long-term. Therefore, the growth of Antarctica is more of a temporary reprieve than anything else.
NASA is currently developing the ICESat-2 to improve the accuracy of measurements taken of Antarctica, which should benefit climatologists in the future.
“ICESat-2 will measure changes in the ice sheet within the thickness of a No. 2 pencil,” Tom Neumann, a glaciologist at Goddard and deputy project scientist for ICESat-2, said. “It will contribute to solving the problem of Antarctica’s mass balance by providing a long-term record of elevation changes.”
ICESat-2 is scheduled to launch in 2018.