Widespread slowdown in thinning rates of West Antarctic Ice Shelves
Fernando Paolo, Alex Gardner, Chad A. Greene, Johan Nilsson, Michael Schodlok, Nicole‐Jeanne Schlegel, H. A. Fricker
Abstract
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.