Fjords are important avenues of water transformation between the open ocean and Greenland tidewater glaciers, but fjord-scale processes cannot yet be resolved by global climate models (GCMs). Therefore, ice-sheet models that are forced from GCMs must rely on parameterizations to approximate fjord-scale processes when prescribing frontal ablation rates or ocean thermal forcing, yet it remains unclear how the choice of parameterization subsequently influences projections of Greenland Ice Sheet (GrIS) mass loss. Here, we use the MALI ice-sheet model to run projections of GrIS to 2100 using ocean thermal forcing from the E3SM global climate model. We compare simulations using various frontal ablation and ocean thermal forcing parameterizations to connect MPAS-Ocean (the ocean component of the E3SM) to MALI, and quantify parameterization impact on GrIS mass loss projections. Our intention in quantifying mass loss projection uncertainty arising from these parameterizations is to help guide parameterization strategies for ISMIP7 and the eventual full coupling of MALI to E3SM.