Contribution of surface and cloud radiative feedbacks to Greenland Ice Sheet meltwater production during 2002–2023

Greenland Ice Sheet meltwater runoff projections are essential for accurate forecasts of global sea-level rise. However, melt depends on complex interactions between climate warming, surface albedo, and clouds, which are challenging to simulate in models. Here we use satellite observations, climate reanalysis, and regional climate model data to constrain the amount of melt due to processes that lower surface albedo and reduce cloud cover. We find that cloud radiative forcing had a small impact on melt during 2002–2023. In contrast, the radiative forcing due to spatiotemporal variability in surface albedo accounted for 10.0 ± 3.7% of total meltwater production. Moreover, we find that a feedback between climate warming and surface albedo amplifies melt by +7.8 ± 1.6 Gt yr−1 K−1. Ice sheet models that do not sufficiently account for this radiative feedback will not only underestimate the current production of meltwater but will also increasingly underestimate it in the future. During 2002−2023, Greenland Ice Sheet meltwater production was minimally affected by cloud radiative forcing, while surface albedo variability contributed substantially, according to results from satellite observations, climate reanalysis, and regional climate models.