Attributing atmospheric phenomena driving Greenland Ice Sheet melt and their future changes

Compound warm and wet atmospheric events play a key role in driving extreme melt of the Greenland Ice Sheet (GIS), yet the relative contribution of different atmospheric phenomena remains poorly quantified. While atmospheric rivers (ARs) are frequently associated with extreme melt episodes, a systematic attribution of GIS melt to distinct types of atmospheric circulation features is still lacking.

Here, we apply a modified version of the Multi Object Analysis of Atmospheric Phenomena (MOAAP) tracking algorithm, optimized for Arctic conditions, to identify and track ARs, cyclones, jets, and frontal systems over Greenland. We quantify precipitation from each phenomenon. Together with temperature anomalies and surface melt, we relate these to individual phenomena and their compound occurrences. Extreme melt events are identified based on runoff, and attribution is performed by relating runoff to the presence and overlap of tracked phenomena over the ice sheet.

The analysis is applied to ERA5 reanalysis data and to PolarRES regional climate model projections. PolarRES includes a historical period and two RCP4.5 simulations representing distinct storylines. The first is characterized by enhanced Arctic amplification, which refelcts stronger local feedbacks. The second by reduced sea ice cover, which can indicate patterns of change is driven more by sea-ice loss and associated surface processes than by relative amplification of near-surface atmospheric warming. Using these scenarios allows us to investigate how differences in large-scale thermodynamic conditions may influence the atmospheric drivers of GIS melt, while applying the same phenomenon-based attribution framework across present-day and future climates.

By combining Arctic-optimized tracking of atmospheric phenomena with a GIS melt attribution framework, we investigate how extreme GIS melt events relate to specific atmospheric configurations and how these relationships may change under enhanced Arctic amplification or reduced sea ice. This study aims to improve our understanding of compound warm–wet events, their links to different types of atmospheric phenomena, and their role in GIS melt, as well as how they will shape the future GIS melt in climate projections.