| Summary: | The Greenland Ice Sheet (GrIS) is a large store of freshwater in the global climate system. Freshwater is discharged from the GrIS into the ocean in three forms: 1) solid ice, through the calving of icebergs; 2) surface melt and runoff, as liquid water through above-sea-level melt and supraglacial streams or subglacial discharge of glaciated areas, and rivers draining watersheds of non-glaciated areas; and 3) submarine melt on the fronts and undersides of marine-terminating glaciers and ice shelves. Beyond sea level rise, the increasing GrIS freshwater flux is raising concerns due to its impacts on global ocean circulation given its proximity to dense water formation sites in the North Atlantic, on marine ecosystems in local and regional waters surrounding Greenland, and on local communities and industries that must navigate rapidly changing ice-related hazards. Notwithstanding its importance, estimates of the timing, magnitude, and distribution of freshwater discharge around Greenland are imperfect due to scarce observations and a limited understanding of how the freshwater is transformed by ice/ocean processes at the ice margins. To tackle this problem, we organized an international workshop to understand the current state of knowledge and identify the critical gaps and next steps in quantifying the future GrIS freshwater flux. The workshop was held prior to the 2018 American Geophysical Union Fall Meeting, included ~40 participants from nine countries, and focused on four goals: 1) connect the communities needed to quantify freshwater input from the GrIS to the ocean; 2) identify the needs of ocean/climate models for oceanic boundary conditions at GrIS margins; 3) define community needs and science gaps; and 4) prioritize how to improve estimates of the freshwater input from the GrIS to the ocean.
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