Modelling Ice-Sheet Contributions to Sea Level: Progress, Uncertainty, and Outlook

Ice sheets play a central role in the Earth system: they regulate global sea level, influence ocean circulation through freshwater fluxes, and interact with the atmosphere via albedo and elevation feedbacks. Over recent decades, both the Greenland and Antarctic ice sheets have been losing mass at an accelerating rate, making them an increasing contributor to observed sea-level rise. This mass loss will continue throughout the 21st century and beyond. Yet, despite major advances in observations and modelling, projections of future ice-sheet mass loss remain affected by deep uncertainties, arising from complex ice dynamics, poorly constrained boundary conditions, and nonlinear interactions with the climate system.

This talk provides a synthesis of recent progress in ice-sheet modelling, with a focus on developments that have reshaped our ability to simulate past and future ice-sheet evolution. We review advances in the representation of key physical processes, including grounding-line dynamics, basal friction, ice–ocean interactions beneath ice shelves, and damage and calving. We then discuss progress in coupling ice-sheet models with atmosphere and ocean models, ranging from improved offline forcings to emerging fully coupled Earth system frameworks, as well as the growing role of coordinated multi-model ensembles and their analysis in characterising uncertainty and identifying robust responses. We conclude by discussing ice-sheet predictability, showing how present-day observations can provide meaningful constraints on future evolution in specific regions, while informing where and why such constraints are not emerging elsewhere.