Low-level aerial surveys aim to understand rapid Antarctic melting

Earth Institute News (Columbia University): Starting this month, a giant NASA DC-8 aircraft loaded with geophysical instruments and scientists will buzz at low level over the coasts of West Antarctica, where ice sheets are collapsing at a pace far beyond what scientists expected a few years ago. The flights, dubbed Operation Ice Bridge, are an effort by NASA in cooperation with university researchers to image what is happening on, and under, the ice, in order to estimate future sea-level rises that might result.

Since 2003, laser measurements of ice surfaces from NASA’s ICESat satellite have shown that vast ice masses in Greenland and West Antarctica are thinning and flowing quickly seaward. Last month, a report in the journal Nature based on the satellite’s measurements showed that some parts of the Antarctic area to be surveyed have been sinking 9 meters (27) feet a year; in 2002, one great glacial ice shelf jutting from land over the ocean on the Antarctic Peninsula simply disintegrated and floated away within days. NASA’s satellite reaches the end of its life this year, and another will not go up until 2015; in the interim, Operation Ice Bridge flights will continue and expand upon the satellite mission. In addition to lasers, the plane will carry penetrating radars to measure snow cover and the thickness of ice to bedrock, and a gravity-measuring system run by Columbia University’s Lamont-Doherty Earth Observatory that will, for the first time, plot the geometry and depth of ocean waters under the ice shelves. The gravity study is seen as key because many scientists believe warm ocean currents may be the main force pulling the ice sheets seaward, melting the undersides of ice shelves and thus removing the buttresses that hold back the far greater masses of ice on land.

“What our colleagues see from modeling of these glaciers is that warm ocean water is providing the thermal energy to melt the ice,” said Lamont geophysicist Michael Studinger, a co-leader of the gravity team who will be on some of the flights. “To really understand how the glaciers are going to behave, we need the firsthand measurements of water shape and depth.” …

The Larsen Ice Shelf in Antarctica viewed from NASA's DC-8 aircraft during the AirSAR 2004 campaign