Uncertainty quantification of the multi-centennial response of the Antarctic ice sheet to climate change

Bulthuis, Kevin, Arnst, Maarten, Sun, Sainan and Pattyn, Frank (2019) Uncertainty quantification of the multi-centennial response of the Antarctic ice sheet to climate change. The Cryosphere, 13 (4). pp. 1349-1380. ISSN 1994-0424

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Official URL: https://doi.org/10.5194/tc-13-1349-2019

Abstract

Ice loss from the Antarctic ice sheet (AIS) is expected to become the major contributor to sea level in the next centuries. Projections of the AIS response to climate change based on numerical ice-sheet models remain challenging due to the complexity of physical processes involved in ice-sheet dynamics, including instability mechanisms that can destabilise marine basins with retrograde slopes. Moreover, uncertainties in ice-sheet models limit the ability to provide accurate sea-level rise projections. Here, we apply probabilistic methods to a hybrid ice-sheet model to investigate the influence of several sources of uncertainty, namely sources of uncertainty in atmospheric forcing, basal sliding, grounding-line flux parameterisation, calving, sub-shelf melting, ice-shelf rheology and bedrock relaxation, on the continental response of the Antarctic ice sheet to climate change over the next millennium. We provide probabilistic projections of sea-level rise and grounding-line retreat, and we carry out stochastic sensitivity analysis to determine the most influential sources of uncertainty. We find that all investigated sources of uncertainty, except bedrock relaxation time, contribute to the uncertainty in the projections. We show that the sensitivity of the projections to uncertainties increases and the contribution of the uncertainty in sub-shelf melting to the uncertainty in the projections becomes more and more dominant as atmospheric and oceanic temperatures rise, with a contribution to the uncertainty in sea-level rise projections that goes from 5 % to 25 % in RCP 2.6 to more than 90 % in RCP 8.5. We show that the significance of the AIS contribution to sea level is controlled by the marine ice-sheet instability (MISI) in marine basins, with the biggest contribution stemming from the more vulnerable West Antarctic ice sheet. We find that, irrespective of parametric uncertainty, the strongly mitigated RCP 2.6 scenario prevents the collapse of the West Antarctic ice sheet, that in both the RCP 4.5 and RCP 6.0 scenarios the occurrence of MISI in marine basins is more sensitive to parametric uncertainty, and that, almost irrespective of parametric uncertainty, RCP 8.5 triggers the collapse of the West Antarctic ice sheet.

Item Type: Article
Additional Information: Funding Information: Acknowledgements. We would like to thank Andy Aschwanden and one anonymous referee for their very helpful comments that helped improve the overall quality and readability of the manuscript. Kevin Bulthuis would like to acknowledge Andreas Wernecke for personal communication about the manuscript. Kevin Bulthuis would like to acknowledge the Fonds de la Recherche Scientifique de Belgique (F.R.S.-FNRS) for its financial support (F.R.S.-FNRS Research Fellowship). Computational resources have been provided by the Consortium des Équipements de Calcul Inten-sif (CÉCI), funded by the Fonds de la Recherche Scientifique de Belgique (F.R.S-FNRS) under grant no. 2.5020.11.
Subjects: F700 Ocean Sciences
F800 Physical and Terrestrial Geographical and Environmental Sciences
F900 Others in Physical Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Rachel Branson
Date Deposited: 20 Sep 2021 15:06
Last Modified: 20 Sep 2021 15:15
URI: http://nrl.northumbria.ac.uk/id/eprint/47287

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