21 Jun 2022
 | 21 Jun 2022
Status: this preprint is currently under review for the journal TC.

The stability of present-day Antarctic grounding lines – Part A: No indication of marine ice sheet instability in the current geometry

Benoît Urruty, Emily A. Hill, Ronja Reese, Julius Garbe, Olivier Gagliardini, Gael Durand, Fabien Gillet-Chaulet, G. Hilmar Gudmundsson, Ricarda Winkelmann, Mondher Chekki, David Chandler, and Petra M. Langebroek

Abstract. Theoretical and numerical work has firmly established that 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 past and future evolution of the Antarctic Ice Sheet. However, hitherto the stability regime of Antarctic Ice Sheet grounding lines in their current position has not been assessed. Here we conduct a systematic numerical stability analysis of all the grounding lines of the Antarctic Ice Sheet to determine if they are currently undergoing irreversible retreat through MISI. To do this, we initialise three state-of-the-art ice-flow models, Úa, Elmer/Ice, and PISM, to replicate the current geometry of the Antarctic Ice Sheet, and then apply small, but numerically significant, perturbations in ocean-induced ice-shelf melt. We find that the grounding lines around Antarctica migrate slightly away from their initial position while the perturbation is applied, and then revert to the initial state once the perturbation is removed. There is no indication of irreversible or self-sustaining retreat. This suggests that present-day grounding-line retreat is driven by external climate forcing alone. Hence, if the currently observed mass imbalance were to be removed, the grounding-line retreat would likely stop. However, under present-day climate forcing, further grounding-line retreat is expected, and our accompanying paper (Part B, Reese et al., 2022) shows that this could eventually lead to a collapse of some marine regions of West Antarctica.

Benoît Urruty et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2022-104', Anonymous Referee #1, 16 Aug 2022
  • RC2: 'Review of Urruty et al.', Alexander Robinson, 28 Aug 2022

Benoît Urruty et al.

Benoît Urruty et al.


Total article views: 1,201 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
854 326 21 1,201 53 11 7
  • HTML: 854
  • PDF: 326
  • XML: 21
  • Total: 1,201
  • Supplement: 53
  • BibTeX: 11
  • EndNote: 7
Views and downloads (calculated since 21 Jun 2022)
Cumulative views and downloads (calculated since 21 Jun 2022)

Viewed (geographical distribution)

Total article views: 1,155 (including HTML, PDF, and XML) Thereof 1,155 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 24 Mar 2023
Short summary
Retreat of the Antarctic grounding lines could destabilise large parts of the ice sheet. We use three ice sheet models to show that the present-day locations of Antarctic grounding lines are stable with respect to a small perturbation away from their current position. This suggests that self-sustained retreat of grounding lines, due to an internal instability, has not begun. Instead, the currently observed retreat is likely due to external forcing alone.