The European Space Agency spacecraft Envisat has detected new fractures (rifts) in the ice bridge that is currently preventing the collapse of the Wilkins Ice Shelf.
The Wilkins Ice-Bridge that still connects it to Charcot and Latady Islands, has already lost a large block of ice that has broken away from the last remaining section of the ice -bridge. The Advanced Synthetic Aperture Radar (ASAR) images taken on April 2nd show rifts expanding along the ice bridge. Additional observation data was obtained from the German Aerospace Center’s TerraSAR-X satellite.
Dr. Angelika Humbert from the Institute of Geophysics, Münster University, and Dr. Matthias Braun from the Center for Remote Sensing, University of Bonn, observed the first new rifts and using the radar information over a period of time, have determined how the rifts are developing as the ice and ocean interact.
ESA has set-up a public website to monitor the ice sheet break-up via ESA’s ‘Webcam from Space’. The ice shelf suffered from many break-ups in 2008. In late February, 425 sq.km (164 sq.mile) of ice calved away, leaving a 6-km (3.75mile) wide ice-bridge strip. By the end of May 2008, a 160 sq.km (62 sq.mile) chunk of ice broke away and reduced the ice bridge to just 2.7 km (1.7 mile) long, leaving it only 900m (960 yard) wide at its narrowest.
"During the last year the ice shelf has lost about 1800 sq.km (695 sq.mile) or about 14% of its size. The break-up events in February and May 2008 happened in just hours, leaving the remaining part of the ice bridge in a fragile situation," Humbert explained. "Rift developments during October and November resulted presumably from the loss of 1220 sq.km (471 sq.mile) along the northern ice front during June and July 2008."
The Antarctic ice sheet was formed over thousands of years by snow accumulation. As the snow compacts to ice and moves to the coast, it floats out on the ocean, forming massive ledges known as ice shelves. Seven ice shelves have disintegrated in the past 20 years in Antartica. The Wilkins Ice Shelf began retreating in the 1990s. Over the last 50 years the Antarctic Peninsula has warmed by 2.5°C, way above the global average and more ice shelf disintegration is expected.
ESA Webcam from Space: http://www.esa.int/esaEO/SEMWZS5DHNF_index_0.html
Trevor Williams is a University of Victoria Mechanical Engineering PhD candidate specialising in renewable energy, power grid modelling and plug-in hybrid electric vehicles. He has a bachelors in Aeronautical Engineering, a Masters in Management Science and over 23 years international experience in the space industry, having worked on Earth observation and telecommunications satellites.
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