Stress transmission across grounding lines and marine ice sheet instability

The stability of marine ice sheets is largely controlled by the dynamic behaviour of the grounding line, i.e., the contact of the bottom of the ice sheet resting on the bedrock with the ocean water. Marine ice sheet instability implies that an ice sheet on a downward sloping bedrock towards the interior will never find stable equilibria, hence leading to ice sheet collapse, unless an upward slope is reached (Schoof, 2007). The latter study shows that steady state solutions using a boundary layer theory for ice flux are in very close agreement with numerical resolutions that resolve the transition zone. However, the time dependent response of grounding line migration is not predicted by this theory. Precise knowledge of this response is essential for assessing the short term impact of accelerated ice discharge on sea level rise.