WASHINGTON - Scientists at Nasa have detected the first signs that a series of glaciers in East Antarctica are shrinking, suggesting significant melting over the past decade and changes within the ocean, the US agency said.
East Antarctica contains vast amounts of ice that could flood coastlines around the world if it all melted. But the region has been considered stable, unlike the rapid melting of glaciers and collapse of ice shelves in West Antarctica, where temperatures have been rising quickly.
But now detailed Nasa maps of the speed of movement and elevation of glaciers along a portion of East Antarctica's coast south of Australia show they are speeding up and thinning.
Until recently, studies have focused on the Totten glacier in East Antarctica, which contains enough ice to raise sea levels by 3m and which has been showing signs of melting because of warming ocean waters. But the Nasa study shows that a group of four glaciers to the west of Totten and a handful to the east are also losing ice, Nasa said on its website.
"Totten is the biggest glacier in East Antarctica, so it attracts most of the research focus," said Catherine Walker, a glaciologist at Nasa's Goddard Space Flight Center in Greenbelt, Maryland, who presented her findings at a press conference on Monday (Dec 10) at the American Geophysical Union meeting in Washington.
"But once you start asking what else is happening in this region, it turns out that other nearby glaciers are responding in a similar way to Totten."
Walker found that four glaciers west of Totten, in an area called Vincennes Bay, have lowered their surface height by about almost 3m since 2008 - before that year, there had been no measured change in elevation for these glaciers.
Farther east, a collection of glaciers along the Wilkes Land coast have approximately doubled their rate of lowering since around 2009, and their surface is now going down by about 0.24m every year.
Walker used simulations of ocean temperature from a model and compared them to actual measurements from sensor-tagged marine mammals. She found that recent changes in winds and sea ice have resulted in an increase to the heat delivered by the ocean waters to the glaciers in Wilkes Land and Vincennes Bay, Nasa said.