The Greenland Ice Sheet gains and loses mass at the surface through snow accumulation in the interior and ice melt at the margins. The net amount mass gained or lost at the surface over the course of a year is termed the surface mass balance, and is a major control on Greenland Ice Sheet evolution. Greenland surface mass balance is highly variable year to year; this variability can impact regional climate, ice sheet dynamics, and the assessment of Greenland ice loss trends. DOE researchers have carried out a surface mass balance variability analysis of a Community Earth System Model (CESM) simulation with Greenland surface mass balance calculations included, to assess changes to Greenland surface mass balance variability from 1850 to 2100. They found a large and significant increase to overall Greenland surface mass balance sensitivity, and tracked this increase to growth of the high-variability zone of the ice sheet where ice is lost (the ablation zone). These findings highlight that increased Greenland Ice Sheet surface mass balance variability is a physically consistent response to anthropogenic climate change, in line with findings of similarly increased variability within other components of the Earth system in a warming world.