Pattern of retreat and disintegration of the Larsen B ice shelf, Antarctic Peninsula

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Abstract
The retreat of the Larsen B ice shelf, Antarctic Peninsula, and the collapse of its northern section are analyzed using satellite images acquired between January 1995 and May 2003. Over 1 week during March 2002, after a period of steady retreat since 1995, 2300 km2 of the ice shelf broke up into many small icebergs. This rapid collapse occurred at the end of an exceptionally warm summer, and after a multi-year period of decreasing surface net mass balance, ice thinning, flow acceleration and widening of rifts. The ice-shelf area decreased from 11 512 km2 in January 1995 to 3463 km2 in March 2002, and 2667 km2 in April 2003. ERS synthetic aperture radar (SAR) images were used to identify ice-shelf zones with different surface morphology, which generated icebergs of different sizes and shapes. The pattern of retreat and break-up, similar to that of Larsen A in 1995, suggests that fracturing enhanced by abundant surface melt played a key role. In addition, the recent changes of grounded and residual floating ice north of Larsen B are analyzed by means of Envisat advanced synthetic aperture radar (ASAR) images up to summer 2003, showing significant loss of grounded ice upstream of those ice-shelf sections which disintegrated in 1995 and 2002.