This project will observe, quantify and model the Thwaites ice-ocean system in the grounding zone, to firmly establish the physics linking ocean forcing and ice-sheet response. The time-dependent cavity will be thoroughly surveyed and instrumented with ocean monitoring devices. Melting will be observed by a network of autonomous sensors and from space over an extended period. The response of the glacier will also be observed. Our enhanced understanding of melting beneath TG’s ice shelf, its grounding zone and its connection with the glacier flow will be built into state-of-the-art coupled ice sheet and ocean models. These physics-rich, high-resolution models will allow the potential sea-level contribution of TG to be bounded with unprecedented fidelity.