Two years ago, Antarctica's Larsen B ice shelf collapsed over the course of 35 days; 3,250 square kilometers of shelf area--an area larger than that of Rhode Island--disintegrated. Two new reports have traced the effects of the collapse on the continent's remaining glaciers and found that they are flowing ever faster into the surrounding Weddell Sea.
"If anyone was waiting to find out whether Antarctica would respond quickly to climate warming, I think the answer is yes," says the lead author of one of the reports, Ted Scambos of the National Snow and Ice Data Center in Boulder, Colo. "We've seen 150 miles of coastline change drastically in just 15 years." Scambos and his colleagues analyzed five images taken by the Landsat 7 satellite before and after the Larsen B breakup as well as data from ICESat, which measures changes in elevation. By tracking changes in crevasses on the glaciers' surfaces, they calculated the speed at which the ice slabs were moving. In the second report, researchers led by Eric Rignot of NASA's Jet Propulsion Laboratory used remote sensing and radar data to calculate the glaciers' movement.
The results suggest that three glaciers--Hektoria, Green and Evans--flowed eight times faster in 2003 than they did in 2000. Two others, Jorum and Crane, moved twice as quickly at the beginning of 2003 than in 2000 and nearly three times as fast by the end of the year. In addition, the findings indicate that glacier elevation dropped by up to 38 meters in the six months following the collapse. The reports appear in the current issue of the journal Geophysical Research Letters. "These two papers clearly illustrate, for the first time, the relationship between ice shelf collapses caused by climate warming, and accelerated glacier flow," Rignot remarks