Record-breaking Greenland ice sheet melt events under recent and future climate

Area of Science:

• Climate Science
• Glaciology
• Environmental Science

Background:

• The Greenland Ice Sheet (GrIS) is crucial for global sea-level rise.
• Intensified summer surface melting and extreme melt events are increasingly observed.
• The underlying mechanisms driving these extreme melt events are not fully understood.

Purpose of the Study:

• To analyze extreme melt events on the GrIS from 1950-2023.
• To differentiate the thermodynamic and dynamic contributions to meltwater production.
• To project future changes in extreme melt events under high-emission scenarios.

Main Methods:

• Utilized an analog-based framework combined with a regional climate model.
• Analyzed extreme melt events spanning from 1950 to 2023.
• Disentangled thermodynamic and dynamic drivers of meltwater production.

Main Results:

• Thermodynamic processes significantly intensified meltwater production, increasing by 25% with circulation analogs and 63% with circulation-analog events.
• The most extreme melt events, including record-breakers in 2012, 2019, and 2021, lacked dynamic precedents.
• Seven of the ten most extreme events occurred after 2000, with anomalies reaching three times the synoptic average.
• Northern Greenland experienced the strongest increases in meltwater production.

Conclusions:

• Climate change is profoundly impacting GrIS melt extremes.
• Future projections (SSP5-8.5, CMIP6) suggest extreme meltwater anomalies could increase by up to +372% by 2100.
• Understanding these mechanisms is critical for predicting future sea-level rise.