The stability of present-day Antarctic grounding lines – Part 1: No indication of marine ice sheet instability in the current geometry
Published in: The Cryosphere, 2023
Hill, E. A.*, Urruty, B.*, Reese, R.*, Garbe, J., Gagliardini, O., Durand, G., Gillet-Chaulet, F., Gudmundsson, G. H., Winkelmann, R., Chekki, M., Chandler, D., Langebroek, P. M.: The stability of present-day Antarctic grounding lines – Part 1: No indication of marine ice sheet instability in the current geometry, The Cryosphere, 17, 3739-3759, DOI: 10.5194/tc-17-3739-2023, 2023. *These authors contributed equally to this work.
Abstract
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 sub-marine 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., 2023) 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.
Official press release
- Potsdam Institute: Stability inspection for West Antarctica shows: marine ice sheet is not destabilized yet, but possibly on a path to tipping
- Northumbria University: West Antarctic ice sheet has not reached its tipping point towards irreversible collapse – yet, new research finds
- Université Grenoble: Perte de glace de la calotte glaciaire de l’Antarctique: son futur n’est pas encore écrit
Media coverage
Selected international media articles:
- English: Euronews, Innovation
- German: Der Standard
- French: Reporterre