Antarctic glaciers' fast melting risks sea-level rise     

March 1, 2009

BEIJING (Xinhuanet) -- Antarctica glaciers are melting faster than before and across a much wider area, thereby threatening to raise sea levels worldwide and forcing migration of people to low-lying areas, according to scientists.     

Earlier, scientists believed the melting was confined to the Antarctic Peninsula, a narrow tongue of land pointing toward South America. But satellite data and automated weather stations now indicate it is more widespread.     
Scientists from British Antarctic Survey (BAS), Durham University and Germany's Alfred Wegener Institute for Polar and Marine Research (AWI) collected boulders deposited by three glaciers in the Amundsen Sea Embayment -- a region currently the focus of intense international scientific attention as it is changing faster than anywhere else on the West Antarctic Ice Sheet's (WAIS) and it has the potential to raise sea-level by around 1.5 meters.     
Analysis of the boulders has enabled the scientists to start constructing a long-term picture of glacier behavior in the region. By the end of the century, the accelerated melting could cause sea levels to climb by 3 to 5 feet (about 0.91 to 1.52 meters)— levels substantially higher than predicted by a major scientific group two years ago.     
Scientists also said the ice shelves that hold the glaciers back from the sea are also weakening.     
In Washington, as part of an overall update on global warming, top researchers Wednesday sounded a similar warning to the U.S. Senate about rising temperatures in the Antarctic.      The head of the Intergovernmental Panel on Climate Change, a group set up by the United Nations, told lawmakers on the Environment and Public Works Committee that Earth has about six more years at current rates of carbon dioxide pollution before it is locked into a future of severe global warming.     
For years, the continent at the bottom of the world seemed to be the only place on the planet not experiencing climate change. Previous research indicated that temperatures across much of Antarctica were staying the same or slightly cooling.     
The big surprise after conducting the research by scientists was exactly how much glaciers are melting in western Antarctica, a vast land mass on the Pacific Ocean side of the continent that is next to the South Pole and includes the Antarctic Peninsula.     
The biggest of the western glaciers, the Pine Island Glacier, is moving 40 percent faster than it was in the 1970s, discharging water and ice more rapidly into the ocean, said Summerhayes, a member of International Polar Year's steering committee.     
The Smith Glacier, also in west Antarctica, is moving 83 percent faster than in 1992, he said.     
The glaciers are slipping into the sea faster because the floating ice shelf that would normally stop them — usually 650 to 980 feet (about 198 to 299 meters) thick — is melting. And the glaciers' discharge is making a significant contribution to increasing sea levels.     
Some people “fear that this is the first signs of an incipient collapse of the west Antarctic ice sheet,” Summerhayes said. “If the west Antarctica sheet collapses, then we're looking at a sea level rise of between 3 feet 4 inches (about 1.01 meters), to nearly 5 feet (about 1.52 meters).”     
Together, all the glaciers in west Antarctica are losing a total of around 114 billion tons per year because the melting is much greater than the new snowfall, he said.