Acceleration of dynamic ice loss in Antarctica from satellite gravimetry

• Published in: Frontiers in Earth Science
• Main Authors: Diener, Theresa, Sasgen, Ingo, Agosta, Cécile, Fürst, Johannes, Braun, Matthias, Konrad, Hannes, Fettweis, Xavier
• Other Authors: Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Deutscher Wetterdienst Offenbach (DWD), Université de Liège
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Antarctica; GRACE/GRACE-FO; ice-dynamic discharge; surface mass balance; sea-level rise (SLR); mass balance; ISMIP6; climate indices; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; The Antarctic; Dronning Maud Land; Bellingshausen Sea; Ronne Ice Shelf; Antarc*; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice Sheet; Ice Shelf
• Online Access: https://hal.archives-ouvertes.fr/hal-03510587; https://hal.archives-ouvertes.fr/hal-03510587/document; https://hal.archives-ouvertes.fr/hal-03510587/file/feart-09-741789.pdf; https://doi.org/10.3389/feart.2021.741789

International audience The dynamic stability of the Antarctic Ice Sheet is one of the largest uncertainties in projections of future global sea-level rise. Essential for improving projections of the ice sheet evolution is the understanding of the ongoing trends and accelerations of mass loss in the context of ice dynamics. Here, we examine accelerations of mass change of the Antarctic Ice Sheet from 2002 to 2020 using data from the GRACE (Gravity Recovery and Climate Experiment; 2002-2017) and its follow-on GRACE-FO (2018-present) satellite missions. By subtracting estimates of net snow accumulation provided by re-analysis data and regional climate models from GRACE/GRACE-FO mass changes, we isolate variations in ice-dynamic discharge and compare them to direct measurements based on the remote sensing of the surface-ice velocity (2002-2017). We show that variations in the GRACE/GRACE-FO time series are modulated by variations in regional snow accumulation caused by large-scale atmospheric circulation. We show for the first time that, after removal of these surface effects, accelerations of ice-dynamic discharge from GRACE/GRACE-FO agree well with those independently derived from surface-ice velocities. For 2002-2020, we recover a discharge acceleration of-5.3 ± 2.2 Gt yr$^{−2}$ for the entire ice sheet; these increasing losses originate mainly in the Amundsen and Bellingshausen Sea Embayment regions (68%), with additional significant contributions from Dronning Maud Land (18%) and the Filchner-Ronne Ice Shelf region (13%). Under the assumption that the recovered rates and accelerations of mass loss persisted independent of any external forcing, Antarctica would contribute 7.6 ± 2.9 cm to global mean sea-level rise by the year 2100, more than two times the amount of 2.9 ± 0.6 cm obtained by linear extrapolation of current GRACE/GRACE-FO mass loss trends.