Next-Generation Modelling of Glacial Isostatic Adjustment

Modern-day changes to sea level can be measured using either tide gauges or satellite altimetry, and these observations provide vital quantitative information about the effects of anthropogenic climate change. Similarly, satellite-based measurements of the Earth’s gravitational field are used to monitor mass loss from the Greenland and Antarctic ice sheets. Such modern-day measurements cannot, however, be straightforwardly interpreted in terms of modern-day processes due to significant contributions from glacial isostatic adjustment (GIA); this being the ongoing deformation of the solid Earth and concomitant sea level change caused by the last deglaciation. It is, therefore, necessary to model and correct for GIA within modern-day observations.

Within the foreseeable future, the only computationally viable approach to the GIA inverse problem that can take account of 3D viscosity variations is to apply gradient-based optimisation (GBO). This approach is widely used in other fields, including weather forecasting, oceanography, and seismic tomography. Recently, the first application of GBO to the GIA inverse problem has been undertaken, and the initial results show great promise. This research has, however, made clear that future large-scale applications of this method are being held back by the computational tools available. The aim of the project is, therefore, the development of new and highly efficient numerical methods to facilitate the application of GBO to the GIA inverse problem. Such focused methodological work is necessary to enable future practical studies aimed at increasing the accuracy of GIA corrections, and hence improving our ability to monitor and understand the Earth’s changing climate.