Response of EC-Earth3 to Antarctic meltwater

Ice-sheet meltwater affects ocean stratification and circulation, sea ice, and ultimately the global climate through various feedback mechanisms. Most current generation global climate models do not include interactive ice sheets and as such do not capture the projected increases in additional meltwater under future emission scenarios. We use the EC-Earth3 coupled climate model to investigate the climate response to various scenarios of Antarctic meltwater input. With the idealized experiments of the Southern Ocean Freshwater Input from Antarctica Model Intercomparison Project (SOFIAMIP), as well as a plausible future meltwater release experiment, we investigate the sensitivity to both amount and location of the freshwater forcing in both the eddy-permitting (0.25°) and the standard, non-eddying (1°) resolution model versions. We find that the amount of freshwater strongly controls the sea ice with associated atmospheric adjustments and feedbacks. We also see that while inserting additional meltwater at the surface enhances stratification increasing sea ice cover, inserting it at depth decreases stratification and enables more ocean heat to be released at the surface. Our results represent improved model physics and support calls for using prescribed Antarctic meltwater input as forcing in the Coupled Model Intercomparison Project to, for example, improve modelled sea ice evolution and sea level trends.