Abstract

The response of the Greenland and Antarctic ice sheets to a changing climate is one of the largest sources of uncertainty in future sea level predictions. The behaviour of the subglacial environment, where ice meets hard rock or soft sediment, is a key determinant in the flux of ice towards the ocean. In this talk I’ll explore three settings in which observations enable us to learn about the response of ice sheets to transient forcing. On the shortest timescales, we’ll examine the rapid drainage of supraglacial lakes and the elastic propagation of subglacial meltwater. We’ll also look at periodically forced grounding zones, where the ice floats onto the water, as a nonlinear response to regular forcing. Finally, we’ll examine in more detail the response of subglacial sediments using modern granular constitutive theories to understand both the steady and transient response of the subglacial environment. The fluid dynamical principles involved, the peeling of elastic sheets as a blister, an elastic `Landau-Levitch’ problem, or of the flow of granular ‘fluids’, while applied at large scales to the glacial system, find their analogue in a host of engineering problems with links to be highlighted along the way.