The Lost Ice of Antarctic
According to a new, comprehensive study by NASA and university scientists, ice loss in Antarctica has increased by 75 percent in the last ten years. It is because of a speed-up in the flow of its glaciers, nearly as great as that observed in Greenland.
An international team led by Eric Rignot of NASA’s Jet Propulsion Laboratory, Pasadena, and the University of California, Irvine, participated in a first-of-its-kind study. They estimated changes in Antarctica’s ice mass between 1996 and 2006, mapping patterns of ice loss on a glacier-by-glacier basis. They found a sharp jump in the ice loss of Antarctica, from enough ice to raise global sea levels by 0.3 millimeters (.01 inches) a year to 1996, to 0.5 millimeters (.02 inches) a year in 2006.
To understand the ice sheet’s mass, the team measured ice flowing out of Antarctica’s drainage basin over 85 percent of its coast line. To reveal the pattern of ice sheet motion toward the sea, they used 15 years of satellite radar data from the European Earth Remote Sensing -1 and -2, Canada’s Radarstat -1, and Japan’s Advanced Land Observing satellites. Those results were compared with estimates of snowfall accumulations in Antarctica’s interior derived from a regional atmospheric climate model spanning the past quarter century.
Another thing that the group found was that the net loss of ice mass from Antarctica’s increased from 112 (plus or minus 91) gigatonnes a year in 1996 to 196 (plus of minus 92) gigatonnes a year in 2006. A gigatonne weighs one billion metric tons or more than 2.2 trillion pounds. These new results re about 20 percent higher over a comparable time frame than those of a NASA study of Antarctic mass balance, which used data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment. This is within the margin of error for both techniques each of which have their strengths and limitations.
According to Rignot, the losses are caused by ongoing and past acceleration of glaciers into the sea. The losses were mainly concentrated in West Antarctica’s Pine Island Bay sector and the northern tip of the Antarctic Peninsula. This is a result of warmer ocean waters, which bathe the buttressing floating sections of glaciers, causing them to thin or collapse. “Changes in Antarctic glacier flow are having a significant if not dominant, impact on the mass balance of the Antarctic ice sheet,” said Rignot. He added that the increased contribution of Antarctica to global sea level rise indicated by the study warrants closer monitoring. “Large uncertainties remain in predicting Antarctica’s future contribution to sea level rise. Ice sheets are responding faster to climate warming than anticipated,” said Rignot.
This entry was posted on Tuesday, February 19th, 2008 at 2:10 am and is filed under Public Relations. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
