Greenland ice sheet climate disequilibrium and committed sea-level rise

Ice loss from the Greenland ice sheet is a major source of present-day sea-level rise (SLR). Process-based models face limitations, including imprecise atmospheric and oceanic coupling. This study presents a complementary, observation-constrained approach that resolves the ice sheet’s geometrical disequilibrium with recent (2000–2019) climate using satellite-derived bare-ice extent, tidewater discharge, and surface mass balance (SMB) data. Greenland’s current imbalance commits at least 274 ± 68 mm of global eustatic SLR, equivalent to a 59 ± 15 × 10³ km² retreat and 3.3% volume loss, regardless of future climate pathway. A perpetually high-melt state analogous to 2012 yields a commitment of 782 ± 135 mm SLR. The committed loss arises from increased mass turnover through precipitation, ice flow discharge, and especially meltwater run-off.

Jason E. Box, Alun Hubbard, David B. Bahr, William T. Colgan, Xavier Fettweis, Kenneth D. Mankoff, Adrien Wehrlé, Brice Noël, Michiel R. van den Broeke, Bert Wouters, Anders A. Bjørk, Robert S. Fausto