Antarctic Glaciers Slipping Swiftly Seaward
Antarctic Glaciers Slipping Swiftly Seaward
A report by thousands of scientists for the 2007-2008 International Polar Year concluded that the western part of the continent is warming up, not just the Antarctic Peninsula.Previously most of the warming was thought to occur on the narrow stretch pointing toward South America, said Colin Summerhayes, executive director of the Britain-based Scientific Committee on Antarctic Research and a member of International Polar Year's steering committee.
"That's equivalent to the current mass loss from the whole of the Greenland ice sheet," Summerhayes said, adding that the glaciers' discharge was making a significant contribution to the rise in sea levels. "We didn't realize it was moving that fast."The glaciers are slipping into the sea faster because the floating ice shelf that would normally stop them usually 650 to 980 feet (200 to 300 meters) thick is melting.The warming of western Antarctica is a real concern."There's some people who fear that this is the first signs of an incipient collapse of the west Antarctic ice sheet," Summerhayes said.
"That has a very large impact," Allison said, adding that extremely large storms which might previously have occurred once in a year would start to occur on a weekly basis.The IPY researchers found the southern ocean around Antarctica has warmed about 0.2 degrees Celsius (0.36 degrees Fahrenheit) in the past decade, double the average warming of the rest of the Earth's oceans over the past 30 years.
"If the west Antarctica sheet collapses, then we're looking at a sea level rise of between 1 meter and 1.5 meters (3 feet, 4 inches to nearly 5 feet)," Summerhayes said.Ian Allison, co-chair of the International Polar Year's steering committee, said many scientists now say the upper limit for sea level rise should be higher than predicted by IPCC.
Other researchers, they noted, have suggested that "the likelihood of the 2003 heat wave in Europe, which led to the death of tens of thousands of people, was substantially increased by increased greenhouse gas concentrations."The new report, in this week's online edition of Proceedings of the National Academy of Science, comes just a week after Christopher Field of the Carnegie Institution for Science told the annual meeting of the American Association for the Advancement of Science that humans are now adding carbon to the atmosphere even faster than in the 1990s.Carbon dioxide and other gases added to the air by industrial and other activities have been blamed for rising temperatures, increasing worries about possible major changes in weather and climate. Carbon emissions have been growing at 3.5 percent per year since 2000, up sharply from the 0.9 percent per year in the 1990s, Field said.
Finding the answers has been key to the 2007-2009 International Polar Year (IPY), a mobilization of 10,000 scientists and 40,000 others from more than 60 countries engaged in intense Arctic and Antarctic research over the past two southern summer seasons — on the ice, at sea, via icebreaker, submarine and surveillance satellite.The 12-member Norwegian-American Scientific Traverse of East Antarctica — the trekkers "coming home" to Troll — was one important part of that work, having drilled deep cores into the annual layers of ice sheet in this little-explored region, to determine how much snow has fallen historically and its composition.Such work will be combined with another IPY project, an all-out effort to map by satellite radar the "velocity fields" of all Antarctic ice sheets over the past two summers, to assess how fast ice is being pushed into the surrounding sea.
posted by MaliK @ 11:02 AM
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