Evolution of marine ice sheets with bed sedimentation

Marine ice sheets terminate in the ocean where they form floating ice shelves or calve icebergs.  They can significantly influence sea level because of the potential for rapid transfer of grounded ice (with thickness greater than floatation) to floating ice shelves or icebergs.  Most models of marine ice sheet evolution assume that the bed elevation stays constant, or responds isostatically to the weight of the ice sheet.  However, it is known that there is sediment deformation beneath the ice sheet (which is in part what enables the ice to move), and that deposition of this sediment in the vicinity of the grounding line can result in the formation of a grounding-zone wedge.  Although it is widely recognised that such a wedge can influence the evolution of the grounding line (where the ice becomes afloat), there is incomplete knowledge about the interaction of the ice and sediment/bed dynamics.

In this study, we build on idealised two-dimensional (flow-line) models of a marine ice sheet to investigate the influence of a deforming sediment layer at the bed.  We examine how different conditions lead to the development of a grounding zone wedge, and how this impacts the possible steady states of the model under given climate forcing, and under different assumptions about the sediment dynamics.  We then examine how the sediment dynamics, and the presence of the grounding-zone wedge, influence the stability of the system.