Weighing the Antarctic Ice Sheet: using GNSS observations of solid Earth deformation to understand contributions to sea level change

Recent studies suggest that much of West Antarctica is underlain by weak mantle. This matters, because ice sheet mass balance estimates must be corrected for the process of glacial isostatic adjustment (GIA), and this correction requires modelling of the solid Earth: if our understanding of mantle structure and rheology is wrong then GIA models will be wrong. It also matters because recent theoretical studies have demonstrated that weaker areas of mantle will introduce negative feedbacks that may mitigate against future ice sheet grounding line retreat. In both cases the mantle viscosity and its spatial variation needs to be quantified.

This project aims to quantify mantle viscosity across West Antarctica via innovative analysis of the viscoelastic response to episodic surface mass loading anomalies, which is revealed through geodetic GNSS observations of solid Earth surface deformation. Over the past two decades, with collaborators including the British Antarctic Survey, we have established a network of continuous GNSS receivers in the Antarctic Peninsula. Depending on the student’s background and interests, the project will involve a balance of high-precision GNSS data processing and time series analysis, analysis of complementary observations and models of present-day ice sheet mass balance (altimetry, gravimetry, meteorology, etc), and geodynamic modelling of Earth’s response to surface mass loading. The approach will allow us to improve GIA models, identify low viscosity areas where negative feedbacks may mitigate against future ice sheet retreat, and, in high viscosity areas, identify regions undergoing dynamic ice loss.