The Influence of Basal Meltwater on the Time-Integrated Sliding Behavior of the Greenland Ice Sheet

Mark Behn, Geology & Geophysics


OCCI Funded Project: 2010


Model-based projections of future ice-sheet contributions to sea level are limited by our poor understanding of the processes responsible for the dramatic recent changes in Greenland and Antarctic ice flow, and the potential for further large changes in ice flow under future warming [IPCC, 2007; Copenhagen Diagnosis, 2009]. It is now recognized that surface meltwater can be rapidly transferred from the surface to the bed of thick (>1 km) ice sheets through conduits that are formed and sustained beneath supraglacial lakes. However, the influence of seasonal meltwater in modulating time-integrated ice-sheet flow remains poorly understood. While recent work suggests that enhanced seasonal lubrication may have less of a destabilizing effect on the Greenland ice sheet than once feared, the interaction between surface melt and ice flow remains poorly constrained and its influence is not well represented in current ice-sheet models. This project will address these issues by modeling the time-averaged (i.e., multi-year) response of an ice sheet to changes in the spatial and temporal distribution of meltwater at the bed. The proposed models will utilize computational approaches for simulating frictional sliding at the ice-bedrock interface in the presence of variable water pressure. These methods are used extensively in the lithospheric dynamics community to model fault behavior, but have not yet been extended to large-scale models of ice sheet flow. The models will be constrained using geophysical and climatological data collected over the last 4–5 years as part of a multi-year effort funded through NSF, NASA, and WHOI’s OCCI and ARI. A key aspect of the proposed work is to allow the PI to build a prototype 2-D ice-sheet model that can be used to formulate a future NSF-OPP proposal for 3-D ice-sheet models