The Arctic coastal margin is long and receives a disproportionately large fraction of the global river discharge. Production in the Arctic tends to be concentrated in the coastal zone and over the continental shelves, rather than in the Arctic basins. As such, understanding how climate-induced changes to Arctic rivers may impact marine production—is important both for understanding the Arctic carbon budget and for resource managers and community members who monitor and rely on coastal food resources. Historically, these important coastal Arctic processes have not been well captured in traditional coarse scale Earth System Models. Here we present a new configuration of the Energy Exascale Earth System Model (E3SM), with Arctic regional refinement coupled to the Model for Scale Adaptive River Transport (MOSART) model, and to the Marine Biogeochemistry Library (MarBL) configured to represent the Biogeochemistry Elemental Cycle (BEC) model. We explore the impact of timing and river inputs on coastal and basin-scale Arctic production and ocean-atmosphere carbon flux. We illustrate model performance over a multi-decadal period and compare model predictions to coarser resolution model estimates.