Title: Impact of deep subglacial groundwater on ice stream flow in West Antarctica (IGIS)
Our project will test the hypothesis that ‘deep subglacial groundwater controls the flow of ice streams in West Antarctica’ with an integrated programme of field measurements and numerical modelling of the Institute Ice Stream (IIS) in the central Weddell Sea sector of the West Antarctic Ice Sheet (WAIS). The IIS is particularly vulnerable to dynamic change and one of the largest sources of uncertainty in predictions of sea level change from Antarctica. Ice streams are the fast-flowing conduits of the WAIS that discharge some 90% of continental ice into the ocean, requiring a substrate of basal till that dilates because it is lubricated well by water. Till is commonly supplied by highly erodible sedimentary rocks emplaced in underlying crustal basins, which therefore control the position of ice streams in the WAIS. The water is usually assumed to be produced and flow in a hydrological system at the ice-till interface, and the underlying sedimentary rocks to be impermeable. Evidence is now growing that this assumption is in fact wrong because these rocks can be more permeable than previously thought, and host to reservoirs of mobile groundwater that interacts hydrologically with the interfacial water system. A major source of water and heat available for basal lubrication may therefore have been overlooked in models of ice stream flow. We will identify the anatomy of the crustal groundwater reservoir beneath the IIS, the spatial and temporal nature of water and heat transfer between it and the interfacial water system, and the inherent effects on the basal lubrication of the IIS, and quantify its vulnerability to future groundwater-modulated dynamic change. If our hypothesis is confirmed then our project will transform our understanding of ice stream flow in the WAIS and fundamentally improve our ability to predict the evolution of and sea level change from the WAIS.