Greenland ice sheet climate disequilibrium and committed sea-level rise

Ice loss from the Greenland ice sheet is a major contributor to contemporary sea-level rise (SLR). While process-based models predict Greenland's deglaciation timescale, their accuracy is limited by model shortcomings, including imprecise atmospheric and oceanic couplings. This study presents a complementary approach, resolving ice sheet disequilibrium using climate data constrained by satellite-derived bare-ice extent, tidewater sector ice flow discharge, and surface mass balance data. The findings indicate that Greenland's ice imbalance with the recent (2000–2019) climate commits at least 274 ± 68 mm SLR from 59 ± 15 × 10³ km² ice retreat, equivalent to 3.3 ± 0.9% volume loss, regardless of 21st-century climate pathways. This is due to increased mass turnover from precipitation, ice flow discharge, and meltwater run-off. Using the high-melt year of 2012 as a perpetual analogue, the ice loss commitment increases to 782 ± 135 mm SLR, highlighting a concerning prognosis for Greenland's future under warming conditions.

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