01 Nov 2022
01 Nov 2022
Status: this preprint is open for discussion.

Widespread slowdown in thinning rates of West Antarctic Ice Shelves

Fernando Paolo1, Alex Gardner1, Chad Greene1, Johan Nilsson1, Michael Schodlok1, Nicole Schlegel1, and Helen Fricker2 Fernando Paolo et al.
  • 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
  • 2Scripps Institution of Oceanography, University of California, San Diego, CA

Abstract. Antarctica’s floating ice shelves modulate discharge of grounded ice into the ocean by providing backstress. Ice shelf thinning and grounding line retreat have reduced this backstress, driving rapid drawdown of key unstable areas of the Antarctic Ice Sheet. If ice shelf loss continues, it may initiate irreversible glacier retreat through the marine ice sheet instability, leading to significant sea level rise. We analyze 26 years (1992–2017) of changes in satellite-derived Antarctic ice shelf thickness, flow and basal melt rates to construct a time-dependent dataset and investigate temporal variability. We found an overall pattern of thinning around Antarctica, with a thinning slowdown starting around 2008 widespread across the Amundsen, Bellingshausen and Wilkes sectors. We attribute this slowdown partly to modulation in external ocean forcing, likely altered in West Antarctica by negative feedbacks between ice shelf thinning rates and grounded ice flow, and sub-ice-shelf cavity geometry and basal melting. Our satellite-derived ice-shelf thickness and basal melt dataset uses a novel data fusion approach, state-of-the-art satellite-derived velocities, and a new surface mass balance modeling. We test the resolution capability of these data with an ice-ocean modeling experiment.

Fernando Paolo et al.

Status: open (until 27 Dec 2022)

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Fernando Paolo et al.

Fernando Paolo et al.


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Short summary
We report on a slowdown in the rate of thinning and melting of West Antarctic ice shelves. We present the most comprehensive assessment of the Antarctic ice shelves to date, where we analyze at continental scale the changes in thickness, flow and basal melt over the past 26 years. We also present a novel firn and surface mass balance model for Antarctica, and a time-dependent data set of ice-shelf thickness and basal melt rates at unprecedented resolution.