Shifting landscapes of coastal flood risk: environmental (in)justice of urban change, sea level rise, and differential vulnerability in New York City

Climate-driven changes in coastal flood risk have enormous consequences for coastal cities. These risks intersect with unequal patterns of environmental hazards exacerbating differential vulnerability of climate related flooding. Here we analyze differential vulnerability of coastal flooding in New York City, USA, as an environmental justice issue caused by shifts in flood risk due to increasing floodplain extents. These extents are represented by updates to the 100-year floodplain by the Federal Emergency Management Agency, and urban changes in land use, land value, and socio-economic characteristics of flood exposed populations. We focus on six local community districts containing disproportionately vulnerable communities. Across our study areas, we observed increases in the floodplain’s extent by 45.7%, total exposed population by 10.5%, and population living in vulnerable communities by 7.5%. Overall flood risk increases regardless of increases in the updated floodplain extent, as do floodplain property values. However, variability is high between community districts; in some cases, increases in exposure coincide with decreases in vulnerability due to shifts in racial demographics and increases in income (i.e. potential floodplain gentrification), while others experienced increases in exposure and vulnerability (i.e. double jeopardy). These findings highlight that the dominant drivers of coastal flood risk in NYC are ongoing real estate development and continued increases in sea level rise and storm severity, both of which have explicit implications for flood vulnerability. We describe the social processes governing development in the flood zone, namely zoning, resilience planning, and the determination of potential flooding severity and related insurance rates. We also discuss how these social drivers of risk intersect with social dimensions of vulnerability due to racist housing markets, and the distributions of public housing and toxic chemical hazards. We conclude with a framework for the analysis of contextual and outcome-based vulnerability to coastal flood hazards, and provide policy recommendations to reduce risks over the medium to long term.