The previous Integrated Earth System Model (iESM, Collins et al., 2015) project linked an Earth System Model (CESM) with GCAM, an integrated assessment (human systems) model. It found that climate feedbacks on the terrestrial system increased ecosystem productivity, resulting in declines in cropland extent and increases in bioenergy production and forest cover. Similarly, ACME includes experiments to understand interactions between climate and human systems in both the carbon and water cycles. It remains unclear, however, how dependent these older iESM results are on the particular land surface model coupled to GCAM. Here we use a one-way coupling to examine how sensitive GCAM outputs are to the choice of driving model. This allows us to both quantify and decompose the variability in GCAM outputs across a wide range of ESM conditions.