The typical displacement metric for sea-level rise adaptation planning is property inundation. However, this metric may underestimate risk as it does not fully capture the wider cascading or indirect effects of sea-level rise. To address this, we propose complementing it by considering the risk of population isolation: those who may be cut off from essential services. We investigate the importance of this metric by comparing the number of people at risk from inundation to the number of people at risk from isolation. Considering inundated roadways during mean higher high water tides in the coastal United States shows, although highly spatially variable, that the increase across the United States varies between 30% and 90% and is several times higher in some states. We find that risk of isolation may occur decades sooner than risk of inundation. Both risk metrics provide critical information for evaluating adaptation options and giving priority to support for at-risk communities. |
