Improved models of West Antarctic glacial isostatic adjustment through new crustal motion data

This project addresses the current uncertainty in the present-day contribution of the West Antarctic Ice Sheet to global sea level rise. These estimates are primarily derived from space geodetic (altimetry or time-variable gravity) measurements, with time-variable gravity data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission the only technique capable of determining ice mass balance for the entire ice sheet. Estimates of ice mass change from the total mass change (observed by GRACE) are, however, severely limited due to the large discrepancies between contemporary models of Antarctic glacial isostatic adjustment (GIA). Indeed, recent published estimates of ice mass change for West Antarctica are swamped by this uncertainty. Global Positioning System (GPS) time series offer important constraints on GIA and, indeed, GPS have been installed in a few of the critical locations. However, the current network of GPS sites in West Antarctica, whilst useful in discriminating between major differences in contemporary GIA models, is too sparse to provide the constraints required to significantly reduce the GIA uncertainty in the GRACE signal / for that a high spatial resolution of GPS sites is required. In particular, the southern Antarctic Peninsula/Ronne Ice Shelf contains a very large GRACE signal, but the current GPS station density there is too sparse to unambiguously determine the origin of the gravity change. Further rock outcrops suitable for additional data collection are available in this region and installing new, more densely spaced, continuous sites would provide the required constraints. Here, we propose to develop improved models of West Antarctic GIA through newly collected long-term GPS data, thereby allowing us to compute new accurate and precise estimates of ice mass contributions to sea level rise from West Antarctica. These results are of direct relevance to NERC's draft strategy (2007-2012) to expand on existing knowledge of the fundamental driving forces and feedbacks of the Earth system through prioritising plans to investigate how the cryosphere responds to global change.