Articles | Volume 7, issue 2
The Cryosphere, 7, 395–406, 2013

Special issue: Ice2sea – estimating the future contribution of continental...

The Cryosphere, 7, 395–406, 2013

Research article 01 Mar 2013

Research article | 01 Mar 2013

Grounding line transient response in marine ice sheet models

A. S. Drouet1, D. Docquier2, G. Durand1, R. Hindmarsh3, F. Pattyn2, O. Gagliardini1,4, and T. Zwinger5 A. S. Drouet et al.
  • 1UJF- Grenoble 1/CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE), UMR 5183, Grenoble, 38041, France
  • 2Laboratoire de Glaciologie, Université Libre de Bruxelles, CP160/03, Av F. Roosevelt 50, 1050 Brussels, Belgium
  • 3British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, UK
  • 4Institut Universitaire de France, Paris, France
  • 5CSC-IT Center for Science Ltd., Espoo, Finland

Abstract. Marine ice-sheet stability is mostly controlled by the dynamics of the grounding line, i.e. the junction between the grounded ice sheet and the floating ice shelf. Grounding line migration has been investigated within the framework of MISMIP (Marine Ice Sheet Model Intercomparison Project), which mainly aimed at investigating steady state solutions. Here we focus on transient behaviour, executing short-term simulations (200 yr) of a steady ice sheet perturbed by the release of the buttressing restraint exerted by the ice shelf on the grounded ice upstream. The transient grounding line behaviour of four different flowline ice-sheet models has been compared. The models differ in the physics implemented (full Stokes and shallow shelf approximation), the numerical approach, as well as the grounding line treatment. Their overall response to the loss of buttressing is found to be broadly consistent in terms of grounding line position, rate of surface elevation change and surface velocity. However, still small differences appear for these latter variables, and they can lead to large discrepancies (> 100%) observed in terms of ice sheet contribution to sea level when cumulated over time. Despite the recent important improvements of marine ice-sheet models in their ability to compute steady state configurations, our results question the capacity of these models to compute short-term reliable sea-level rise projections.