Coarse spatial resolutions reduce computational costs but poorly resolve complex topographies. Our simulations of an alpine ice field at 50 m to 2 km resolution show similar ice areas, yet much higher volumes at coarser resolutions. Resolutions of 300 m and finer accurately capture topographically constrained flow, while coarse resolutions flatten mountain slopes and peaks, affecting ice velocities, thickness, and thermal regimes which emphasizes the need for sufficiently high-resolution models.