The simulation of ice sheet-climate interaction such as surface mass balance fluxes are sensitive to model grid resolution. Here we simulate the multicentury evolution of the Greenland Ice Sheet (GrIS) and its interaction with the climate using the Community Earth System Model version 2.2 (CESM2.2) including an interactive GrIS component (the Community Ice Sheet Model v2.1 [CISM2.1]) under an idealized warming scenario (atmospheric CO2 increases by 1% yr−1 until quadrupling the pre-industrial level and then is held fixed). A variable-resolution (VR) grid with 1/4◦ regional refinement over broader Arctic and 1◦ resolution elsewhere is applied to the atmosphere and land components, and the results are compared to conventional 1◦ lat-lon grid simulations to investigate the impact of grid refinement. An acceleration of GrIS mass loss is found at around year 110, caused by rapidly increasing surface melt as the ablation area expands with associated albedo feedback and increased turbulent fluxes. Compared to the 1◦ runs, the VR run features slower melt increase, especially over Western and Northern Greenland, which slope gently towards the peripheries. This difference pattern originates primarily from the weaker albedo feedback in the VR run, complemented by its smaller cloud longwave radiation. The steeper VR Greenland surface topography favors slower ablation zone expansion, thus leading to its weaker albedo feedback. The sea level rise contribution from 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.
