More than the climate: an exploration of coordinated governance for sea level rise adaptation in Boston

Abstract As sea level rise intensifies coastal risk, adaptation is often hampered by fragmented governance. While existing research has considered coastal adaptation governance from multiple lenses, there are few models that attempt to capture and quantify differences between adaptation outcomes under contrasting governance regimes. This study develops a highly stylized agent-based model of Boston Harbor to evaluate how three adaptation regimes—non-cooperation, voluntary cooperation, and a centralized regional authority—perform under varying assumptions about sea level rise, discounting, financing access, and flood variability. Results show that coordinated governance, particularly through a regional authority, can reduce cumulative damage and increase net benefits, although adaptation costs rise. However, these gains can be conditional: under scenarios with modest sea level rise or abundant financing, voluntary or uncoordinated adaptation may perform similarly. In some cases, we demonstrate how specific agents fare worse under cooperative regimes, especially in voluntary coalitions. Notably, governance structure, financing, and discounting explain more outcome variation than stochastic flood events—but a large share of variance remains unexplained, pointing to the influence of local dynamics and emergent behavior. Although representing coastal governance contains many uncertainties, these findings reinforce perceptions that regional solutions can help avoid significant damage from future flood events.