for National Geographic News
Like a slapstick comedian slipping on banana peels, Antarctica's ice sheets slide more quickly into the sea when they hit under-ice lakes, a new study shows.
But the finding is anything but funny, since the slippery motion could have serious implications for the way ice sheets respond to global warming.
Ice is continually sliding off Antarctica and into the sea. In ice streams, inland ice speeds into the ocean more than ten times faster than the rest of the ice sheet.
Using satellite images and elevation data, the study team found four new, large under-ice lakes right at the start of a massive ice stream in East Antarctica.
The stream currently dumps 35 billion tons (31.8 billion metric tons) of ice into the sea each year.
"We think that those subglacial lakes are the reason why these ice streams are there," said Michael Studinger, a co-author of the study and a geophysicist at Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York.
The lakes, buried deep below the miles-thick ice sheet, appear to provide water and heat that lubricate the ice sheet, creating ice streams, the team concludes.
"This makes the lakes really important," Studinger added, "because they impact how the ice sheet responds to changes in climate."
The new study, which will appear in tomorrow's issue of the journal Nature, focused on the Recovery Glacier ice stream.
The Recovery stream, one of the world's largest, is 175 miles (280 kilometers) wide at its start and snakes its way more than 400 miles (600 kilometers) to the sea.
Despite its size, Studinger described the Recovery region as "one of the most inaccessible places on Earth."
SOURCES AND RELATED WEB SITES