TY - JOUR
T1 - The stability of present-day Antarctic grounding lines – Part 1
T2 - No indication of marine ice sheet instability in the current geometry
AU - Hill, Emily A.
AU - Urruty, Benoît
AU - Reese, Ronja
AU - Garbe, Julius
AU - Gagliardini, Olivier
AU - Durand, Gaël
AU - Gillet-Chaulet, Fabien
AU - Gudmundsson, G. Hilmar
AU - Winkelmann, Ricarda
AU - Chekki, Mondher
AU - Chandler, David
AU - Langebroek, Petra M.
N1 - Funding information: This work is part of the TiPACCs project, which receives funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 820575. The Elmer/Ice computations presented in this paper were performed using HPC resources of CINES under the allocation 2021-A0060106066 made by GENCI. We further acknowledge the European Regional Development Fund (ERDF), the German Federal Ministry of Education and Research (BMBF), and Land Brandenburg for supporting this project by providing resources on the high-performance computer system at the Potsdam Institute for Climate Impact Research. The development of PISM is supported by NSF grant nos. PLR-1644277 and PLR-1914668 and NASA grant nos. NNX17AG65G and 20-CRYO2020-0052. We acknowledge the use of the Northumbria University HPC facility Oswald to perform the Úa simulations.
PY - 2023/9/7
Y1 - 2023/9/7
N2 - Theoretical and numerical work has shown that under certain circumstances grounding lines of marine-type ice sheets can enter phases of irreversible advance and retreat driven by the marine ice sheet instability (MISI). Instances of such irreversible retreat have been found in several simulations of the Antarctic Ice Sheet. However, it has not been assessed whether the Antarctic grounding lines are already undergoing MISI in their current position. Here, we conduct a systematic numerical stability analysis using three state-of-the-art ice sheet models: Úa, Elmer/Ice, and the Parallel Ice Sheet Model (PISM). For the first two models, we construct steady-state initial configurations whereby the simulated grounding lines remain at the observed present-day positions through time. The third model, PISM, uses a spin-up procedure and historical forcing such that its transient state is close to the observed one. To assess the stability of these simulated states, we apply short-term perturbations to submarine melting. Our results show that the grounding lines around Antarctica migrate slightly away from their initial position while the perturbation is applied, and they revert once the perturbation is removed. This indicates that present-day retreat of Antarctic grounding lines is not yet irreversible or self-sustained. However, our accompanying paper (Part 2, Reese et al., 2023a) shows that if the grounding lines retreated further inland, under present-day climate forcing, it may lead to the eventual irreversible collapse of some marine regions of West Antarctica.
AB - Theoretical and numerical work has shown that under certain circumstances grounding lines of marine-type ice sheets can enter phases of irreversible advance and retreat driven by the marine ice sheet instability (MISI). Instances of such irreversible retreat have been found in several simulations of the Antarctic Ice Sheet. However, it has not been assessed whether the Antarctic grounding lines are already undergoing MISI in their current position. Here, we conduct a systematic numerical stability analysis using three state-of-the-art ice sheet models: Úa, Elmer/Ice, and the Parallel Ice Sheet Model (PISM). For the first two models, we construct steady-state initial configurations whereby the simulated grounding lines remain at the observed present-day positions through time. The third model, PISM, uses a spin-up procedure and historical forcing such that its transient state is close to the observed one. To assess the stability of these simulated states, we apply short-term perturbations to submarine melting. Our results show that the grounding lines around Antarctica migrate slightly away from their initial position while the perturbation is applied, and they revert once the perturbation is removed. This indicates that present-day retreat of Antarctic grounding lines is not yet irreversible or self-sustained. However, our accompanying paper (Part 2, Reese et al., 2023a) shows that if the grounding lines retreated further inland, under present-day climate forcing, it may lead to the eventual irreversible collapse of some marine regions of West Antarctica.
U2 - 10.5194/tc-17-3739-2023
DO - 10.5194/tc-17-3739-2023
M3 - Article
SN - 1994-0424
VL - 17
SP - 3739
EP - 3759
JO - The Cryosphere
JF - The Cryosphere
IS - 9
ER -