Antarctic glaciers are melting faster than previously thought, which could lead to an unprecedented rise in sea levels, scientists said Wednesday.
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.
Satellite data and automated weather stations indicate that "the warming we see in the peninsula also extends all the way down to what is called west Antarctica," he told The Associated Press. "That's unusual and unexpected."
During the International Polar Year, thousands of scientists from more than 60 countries engaged in intense Arctic and Antarctic research over the past two southern summer seasons — on the ice, at sea, and via icebreaker, submarine and surveillance satellite.
The biggest west Antarctic glacier, the Pine Island Glacier, is moving 40 percent faster than it was in the 1970s, discharging water and ice more rapidly into the ocean, Summerhayes said.
The Smith Glacier, also in west Antarctica, is moving 83 percent faster than it did in 1992, he said.
All the glaciers in the area together lose a total of around 103 billion tons (114 billion U.S. tons) per year because the discharge is much greater than the new snowfall, he said.
"That's equivalent to the current mass loss from the whole of the Greenland ice sheet," he 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."
Antarctica's average annual temperature has increased by about 1 degree Fahrenheit (0.56 degrees Celsius) since 1957, but is still 50 degrees Fahrenheit (45.6 degrees Celsius) below zero, according to a recent study by Eric Steig of the University of Washington.
Summerhayes said the glaciers were slipping into the sea faster because the floating ice shelf that would stop them — usually 200 to 300 meters (656 to 984 feet) thick — is melting.
Sea levels will rise faster than predicted by the Intergovernmental Panel on Climate Change, Summerhayes said.
An IPCC panel in 2007 predicted warmer temperatures could raise sea levels by 30 to 50 inches (0.7 to 1.3 meters) this century, which could flood low-lying areas and force millions to flee.
"If the west Antarctica sheet collapses, then we're looking at a sea level rise of between 1 meter and 1.5 meters," Summerhayes said.
The IPY researchers found that 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, he said.
The warming of western Antarctica is a real concern Summerhayes said. "There's some people who fear that this is the first signs of an incipient collapse of the west Antarctic ice sheet."