Simulating Antarctic marine ice sheet stability and multi-century contributions to sea level rise
Funding source: Academy of Finland
Project duration: 1.9.2015 – 31.8.2019
Project website: Arctic Centre, University of Lapland
What we are doing:
Understanding and predicting the behaviour of the Antarctic Ice Sheet (AIS) on decadal to centennial time scales is of global importance to policy decisions, mainly due high uncertainty in the AIS contribution to sea level change. Significant regions of the AIS rest on bedrock below sea level and may be vulnerable to Marine Ice Sheet Instability (MISI), a mechanism for rapid and potentially irreversible discharge of ice. Due to large uncertainty as to which basins are vulnerable to MISI, and how rapid their unstable retreat might be, even the sign of the contribution of the AIS to sea level rise remains uncertain according to the fifth assessment report of the Intergovernmental Panel on Climate Change.
Ice sheet models capable of simulating both grounding line migration and the full stress field within the ice have not yet been applied to transient simulations of the AIS, and thus have not yet been employed to conduct a whole-ice sheet study of potential vulnerability to MISI.
The project will address this deficit by combining new research results with new developments to a state-of-the-art ice sheet model, Elmer/Ice to enable transient AIS simulations. The research is implemented by a small team with a unique combination of skills in sea level studies, marine ice sheet dynamics, and ice sheet model development.
The objectives of the project are:
1. Develop Elmer/Ice to be capable of multi-century simulations of the AIS. The key developments are in progress: current work underway by the team is showing that a pressure dependent sliding law reduces computational expense for simulating grounding line migration; an iterative approach to matrix inversion in Elmer/Ice increases efficient parallel scaling; runtime mesh adaptivity, making use of existing Elmer/Ice features, will allow capture retreating outlet glaciers.
2. Assess which Antarctic catchment systems are vulnerable to marine ice sheet stability. This objective will be achieved through sensitivity experiments of up to 1000 years in which the ocean and atmospheric forcing will be varied.
3. Provide projections of Antarctic contribution to sea level rise over the next 200 years. Elmer/Ice simulations will be forced by climate model output from the Coupled Model Intercomparison Project, which are in turn forced by Representative Concentration Pathways, in a small ensemble of simulations designed to quantify uncertainty in AIS behaviour.
The project is led by the Arctic Centre / University of Lapland. CSC's role in the project is to act as consultant on use of the ice dynamic computer model Elmer/Ice. Elmer is an open source multiphysical simulation software mainly developed by CSC. Furthermore, CSC will assist in the development of mesh adaptivity and iceberg calving in Elmer/Ice, and troubleshooting Elmer/Ice simulations of the Antarctic Ice Sheet.