After years of gloom and doom warnings by experts that the poles are melting rapidly and sea levels will shoot up, a new NASA study reports that Antarctic ice accumulation that started 10,000 years ago is today adding enough ice to the continent to more than make up for the increased losses from its thinning glaciers – and has been doing this for a long time. This study is in contradiction to the conclusions of Intergovernmental Panel on Climate Change (IPCC) 2013, which stated that Antarctica was losing its land ice. This study challenges many other studies. According to satellite data analysis, the Antarctic Ice Sheet experienced a net gain in 1992 from 2001,. Each year it gained 112 trillion tons of ice. The net gain from 2003 up to 2008 slowed down to 83 trillion tons each year. However, over a 16-year period, the net gain has been considerable. Diagram showing mass change rates from ICESat 2003-2008 in Antarctica. Image: www.nasa.gov. Credits to Jay Zwally/ Journal of Glaciology. The researchers published their results in the Journal of Glaciology. Jay Zwally (a NASA Goddard Space Flight Center glaciologist in Greenbelt) stated that ice gains in Antarctica outweigh any losses. He is the lead author of the study. The main difference is in East Antarctica, West Antarctica, and the interior. There, we see a greater ice loss than elsewhere. “The team measured both small elevation changes across large areas as well as large, more localized changes,” Zwally said. Zwally and his colleagues calculated the extent to which the ice sheets are growing or shrinking from changes in the surface heights that were measured using satellite altimeters. The total snowfall on an icesheet is different from the amount that flows down and out to the sea. This means the surface height of the sheet changes, and the mass shrinks and grows. In the past decade, mass loss has increased in certain areas of the continent like the Antarctic Peninsula. (Image: www.nasa.gov. Zwally says that the net loss could be reversed in the near future. However, Zwally cautions that it may only take several decades before Antarctica’s current growth slows down. Zwally said: “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 – I don’t think there will be enough snowfall increase to offset these losses.” Radar altimeters on two European Space Agency European Remote Sensing (ERS) satellites analyzed changes in surface height of the Antarctic ice sheet from 1992 to 2001, and the laser altimeter on NASA’s Ice, Cloud and land Elevation Satellite (ICESat) did the same from 2003 to 2008. Zwally pointed out that while other researchers have assumed that the elevation gains observed in East Antarctica are due to recent increases in snow accumulation, he and his team used meteorological data starting in 1979 to show that snowfall in that area actually declined by 11 billion tons per year during both the ERS and ICESat periods. The whole region of East Antarctica has been thickening since a long period of time. Other researchers also used data from snow cores that derived information on the accumulation of snow over tens to thousands of years. Zwally said: “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.” The extra snowfall that started 10,000 years ago has been gradually accumulating on the ice sheet and compacting into solid ice over thousands of years, thickening the East Antarctica ice and the interior of West Antarctica by an average of 1.7 centimeters (0.7 inches) annually. The relatively minor thickening that has been sustained for several thousand years over this vast area of Antarctica corresponds to an extremely significant ice loss. This is enough to compensate for losses due to fast-flowing glaciers elsewhere on the continent, and to reduce the global sea-level rise. Zwally and his colleagues found that East Antarctica had experienced a steady mass increase in thickness from 1992 at 200 trillion tons per year, while West Antarctica and the Antarctic Peninsula saw ice loss of 65 trillion tons each. Zwally shared both good and bad news. “The good news: Antarctica isn’t currently contributing to sea-level rise but is actually taking 0. 23 Millimeters per Year away. This is bad news. This is also bad news. 27 millimeters of sea-level rise per year that was attributed to Antarctica by the IPCC report may not be coming from Antarctica. The satellite is due to launch in 2018. Tom Neumann is a Goddard glaciologist and deputy project scientist of ICESat-2. He stated: “ICESat-2 measures changes in the ice sheets within the thicknesses of a No. 2 pencil. The Memorandum of Understanding between Australian and Chinese scientists has been signed. The two countries will share their research and knowledge on Antarctic sea-ice to develop better forecasting models that will aid ships in Antarctic navigation. Citation: “Mass Gains of Antarctic Ice Sheet Exceed Losses,” Zwally H. Jay, Li, Jun, Robbins John W., Saba Jack L., Yi, Donghui3 and Brenner Anita C. Journal of Glaciology. October 29, 2015. DOI: http://dx.doi.org/10.3189/2015JoG15J071. Video – Ice net gain in Antarctica
Antarctica is gaining ice, new NASA study shows
