THINNING HISTORY OF THE FOUNDATION-THIEL TROUGH ICE STREAM: A KEY CONTROL ON DEGLACIATION OF THE WEST ANTARCTIC ICE SHEET, WEDDELL SEA EMBAYMENT

The Antarctic ice sheet is the largest on earth and any instability is likely to dominate global sea level change. We therefore require models of the ice sheet to make more reliable and robust predictions of future change. One problem in meeting this challenge is the lack of past data on deglaciation with which to initialize and calibrate the models. This problem has been particularly acute in the Weddell Sea embayment and in particular its eastern part where the Foundation - Thiel Trough has been a principal drainage route for the West Antarctic Ice Sheet (WAIS), and its southern extension may be a potential location for future instability. We propose here an integrated field and modelling study that will exploit the opportunity of several emerging field datasets from a range of different disciplines, collect fresh data from a crucial location, and investigate past and future deglaciation using sophisticated ice sheet models. To understand the history of ice thinning and retreat along the trough we will adopt a dipstick approach to survey the Foundation Ice Stream, an upstream extension of the ice stream that occupied the trough during the last ice age. We will determine the thinning history of this Foundation-Thiel Trough Ice Stream from geomorphology and exposure age dating: techniques that have been used effectively to provide insight into ice sheet history in other regions of Antarctica. We will apply a 3D model - incorporating significant recent theoretical advances - to the whole of the WAIS in order to understand the forcing mechanisms for the ice stream history we measure. We will go on to use this model to predict the likely future stability of the WAIS in terms of both long-term trajectory and any response to climate change scenarios, and in particular whether it will retreat further along the Foundation-Thiel Trough.