Isolation: Revising the estimated risk of sea-level rise

Abstract The typical displacement metric for sea-level rise adaptation planning is parcel inundation. However, this metric does not fully capture the wider cascading or indirect effects of sea-level rise. To address this, we propose the consideration of population isolation: those who cannot access essential services. Based on this metric, we find a 39–464% increase in the number of people considered at-risk, compared to the risk from parcel inundation, when considering inundated roadways during mean higher high water tides in the coastal U.S. We also find that isolation may occur decades sooner than parcel inundation. Both estimates of risk are critical elements for evaluating adaptation options and prioritizing support for at-risk communities.