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solonavi 28 April 2007 Global Warming, Technology 87 views No Comment Print This Post  Email This Post

European Space Agency

As climate change continues to make headlines across the world, participants at the 2007 Envisat Symposium this week are hearing how Earth observation satellites allow scientists to better understand the parameters involved in global warming and how this is impacting the planet.

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Average temperatures in the Antarctic Peninsula have risen over the last 50 years by half a degree Celsius a decade and are having an impact on the ice shelves and glaciers. Innsbruck University’s Professor Helmut Rott has been observing the accelerated retreat and break-up of the Larsen Ice Shelf on the Antarctic Peninsula in the face of this warming through radar images acquired by ESA’s ERS and Envisat satellites.

The retreat has been accelerating since 1992 and has culminated in two collapse events: Larsen-A in January 1995 and Larsen-B in March 2002. Envisat captured the disintegration of the 200-metre-thick Larsen-B Ice Shelf, which researchers estimate had been stable since the last ice age 12 000 years ago.

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In addition to mapping ice boundaries, Rott used repeat-pass ASAR image data to map the flow velocities of glaciers. All the glaciers, where the buttressing ice had disappeared, have accelerated significantly. The retreat of grounded ice and the accelerated ice export due to increased velocity result in strongly negative mass balance of the glaciers.

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Envisat’s ASAR image, acquired on 22 March 2007, of Larsen-B Ice Shelf with previous ice boundaries at different dates between 1992 and 2002. The ice boundaries were derived from ERS SAR and Envisat’s ASAR images.