Variations in the extent and elevation of the Larsen A and B ice shelves, Antarctica, derived from multiple datasets

Abstract

Accurate measurements of retreat and progressive lowering of ice shelves are critical for estimating the mass balance of the Antarctic ice sheet under projected warming. Ice shelf extent was extracted from declassified aerial photographs and modern satellite images (Landsat and Moderate Resolution Imaging Spectroradiometer imagery), and a 48-year time series of the areal extents of the Larsen A ice shelf (LAIS) and the Larsen B ice shelf (LBIS) was compiled. In addition, we characterize the surface elevation changes of the LAIS and LBIS over the last two decades by combining the Ocean Topography Experiment/Poseidon and the Envisat Radar Altimeter-2 using the collinear analysis method. The Larsen ice shelf displayed no significant changes until the late 1980s, whereas the LAIS has retreated rapidly since 1986, and the LBIS has followed a similar pattern since the early 1990s. The LAIS and LBIS have already diminished by ∼14,000 km2 in total since 1968. As the ice shelves retreated, the surface elevations of the LAIS and LBIS exhibited progressive lowering from 1992 to 2010, with the lowering rate of the LAIS significantly greater than that of the LBIS. The remaining ice of the LAIS was lowered at a rate of 0.45 m a − 1 from 1992 to 2001, and the remnant LBIS was lowered at a rate of 0.07 m a − 1 from 1992 to 2010. In response to the continuous retreat of the LAIS and LBIS, their surface elevations are very sensitive to the collapse and retreat of the ice shelves.