Future freshwater input for Greenland's fjords

Greenland’s fjords receive, transport, and modulate freshwater from the atmosphere, ice masses and tundra. In this study, we estimate future changes in freshwater input from five sources: Greenland Ice Sheet (GrIS) runoff, glacier and ice cap (GIC) runoff, solid ice discharge, tundra runoff from rain or seasonal snowmelt, and direct precipitation into fjords. We examine changes in these five sources across seven climatologically distinct regions using three Earth System Model—Regional Climate Model (ESM-RCM) combinations for three Shared Socioeconomic Pathways through 2100. We use statistically downscaled RCM output fluxes and Community Ice Sheet Model (CISM) projections for solid ice discharge. We find that across scenarios and regions, GrIS runoff will become the largest source to fjord freshwater, except in the Southeast, which under low- and medium-emission scenarios remains a region dominated by solid ice discharge. The seasonal cycle of freshwater input will shift towards earlier snowmelt and prolonged runoff seasons, driven by a reduced land ice retention/refreezing fraction and late-season increases in rainfall (15\%). The shift to a more GrIS-runoff-dominated regime could alter the properties of freshwater entering Greenland’s coastal waters and consequently impact local ecosystems.