Monday, 14 November 2011
A huge, emerging crack has been discovered in one of Antarctica's glaciers, with a NASA plane mission providing the first-ever detailed airborne measurements of a major iceberg breakup in progress.
NASA's Operation Ice Bridge, the largest airborne survey of Earth's polar ice ever flown, is in the midst of its third field campaign from Punta Arenas, Chile.
The crack was found in Pine Island Glacier , which last calved a significant iceberg in 2001; some scientists have speculated recently that it was primed to calve again. But until an Oct. 14 IceBridge flight, no one had seen any evidence of the ice shelf beginning to break apart. Since then, a more detailed look back at satellite imagery seems to show the first signs of the crack in early October.
"We are actually now witnessing how it happens and..
it's very exciting for us," said IceBridge project scientist Michael Studinger of NASA's Goddard Space Flight Center in Greenbelt, Md. "It's part of a natural process, but it’s pretty exciting to be here and actually observe it while it happens."
Pine Island Glacier is of particular interest to scientists because it is big and unstable and so is one of the largest sources of uncertainty in global sea level rise projections.
When the iceberg breaks free, it will cover about 340 square miles (880 square kilometers) of surface area. Radar measurements suggested the ice shelf in the region of the rift is about 1,640 feet (500 meters) feet thick, with only about 160 feet of the shelf floating above water and the rest submerged.
It is likely that once the iceberg floats away, the leading edge of the ice shelf will have receded farther than at any time since its location was first recorded in the 1940s.