The Role of a Dynamic Greenland Ice Sheet in Future Climate: Insights from Multi-Centennial Coupled UKESM Simulations

The Greenland Ice Sheet (GrIS) holds an ice volume equivalent to ~7 m of global sea-level rise, making its future evolution a critical component of sea-level projections. The rate and magnitude of ice loss strongly depend on ice–climate feedbacks, yet most Earth System Models (ESMs) still treat ice sheets as static entities, limiting their ability to simulate these essential interactions. The UK Earth System Model (UKESM) is a state-of-the-art ESM which includes dynamic models of the Greenland and Antarctic ice sheets, as well as a sophisticated climate - ice sheet coupling based on the explicit exchanges of water and energy. However, the impacts of this interactivity on projected climate and ice sheet evolution remain insufficiently quantified.

To assess the role of ice–climate feedbacks within a sophisticated, coupled ESM framework, we performed two multi-century climate simulations under high-emissions forcing (SSP5–8.5) using UKESM: a control run with a fixed GrIS geometry, and an interactive run in which the ice sheet evolves freely in response to climate drivers. For computational efficiency, an ice sheet acceleration mode was applied from 2100 onward, whereby the ice sheet model integrates ten years for each year of atmospheric-oceanic simulation. This method effectively projects the ice sheet’s evolution over two millennia (2100–4100) within a 200-year atmosphere-ocean simulation (2100–2300), although it does not fully include feedbacks from meltwater-driven changes in ocean circulation.

By comparing these simulations, we quantify the impacts of simulating a dynamic GrIS in the Earth System, ranging from local alterations in Greenland’s mass balance and sea-level contribution to remote downstream effects on atmospheric circulation. We identify that positive feedbacks—primarily from reduced surface albedo and lowering ice sheet elevation—become dominant after 2100, driving accelerated mass loss and influencing North Atlantic atmospheric circulation patterns. This study highlights the importance of two-way ice–climate coupling in ESMs for improving predictions of future climate and sea level changes.