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The simulation of ice sheet-climate interaction such as surface massbalance fluxes are sensitive to model grid resolution. Here we simulatethe multicentury evolution of the Greenland Ice Sheet (GrIS) and itsinteraction with the climate using the Community Earth System Modelversion 2.2 (CESM2.2) including an interactive GrIS component (theCommunity Ice Sheet Model v2.1 [CISM2.1]) under an idealized warmingscenario (atmospheric CO2 increases by 1% yr−1 until quadrupling thepre-industrial level and then is held fixed). A variable-resolution (VR)grid with 1/4◦ regional refinement over broader Arctic and 1◦ resolutionelsewhere is applied to the atmosphere and land components, and theresults are compared to conventional 1◦ lat-lon grid simulations toinvestigate the impact of grid refinement. An acceleration of GrIS massloss is found at around year 110, caused by rapidly increasing surfacemelt as the ablation area expands with associated albedo feedback andincreased turbulent fluxes. Compared to the 1◦ runs, the VR run featuresslower melt increase, especially over Western and Northern Greenland,which slope gently towards the peripheries. This difference patternoriginates primarily from the weaker albedo feedback in the VR run,complemented by its smaller cloud longwave radiation. The steeper VRGreenland surface topography favors slower ablation zone expansion, thusleading to its weaker albedo feedback. The sea level rise contributionfrom the GrIS in the VR run is 53 mm by year 150 and 831 mm by year 350,approximately 40% and 20% smaller than the 1◦ runs, respectively.