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Comment

Future risk to coastal housing stock due to sea level rise plus storms is not adequately represented by FEMA Flood Insurance Studies (FIS) and FEMA Flood Insurance Rate Maps (FIRMs) because current methods do not incorporate projected rising sea levels.

A 2019 Research Report by Climate Central and Zillow using well-established sea level rise models and flood models found that recent housing growth rates are faster in ten-year flood-risk zones than in safer zones in a third of all coastal states. It found that unchecked greenhouse gas emissions would expose 3.4 million existing homes worth $1.75 trillion to a 10% or higher annual risk of flooding by 2100. For more information and methodology visit https://www.climatecentral.org/news/ocean-at-the-door-new-homes-in-harm…

In addition, recent analysis published in Environmental Research Letters (https://iopscience.iop.org/article/10.1088/1748-9326/abb266) by scientists at Climate Central, UC Berkeley, San Francisco State University along with staff from the National Housing Trust helps to close the gap in the understanding of the risk rising seas and coastal flooding poses to the nation’s affordable housing stock. The combination of physical vulnerability of affordable housing, socioeconomic vulnerability, and more frequent flooding due to sea level rise presents a triple threat within the next 30 years to residents and owners of the country’s already scarce affordable housing. The number of affordable housing units at risk from coastal flooding and sea level rise is expected to increase more than three-fold over the next three decades. By 2050, virtually every coastal state is expected to have at least some affordable housing exposed to more than one “coastal flood risk event” per year, on average—up from about half of coastal states in the year 2000. Each affordable housing building’s footprint was assessed for the annual probability of experiencing at least one coastal flood risk event in a given year. These building-level probabilities were integrated to estimate the total expected annual exposure within various administrative areas.

Climate Central’s web tool allows users to explore what affordable housing in the U.S. could be threatened by sea level rise and coastal flooding in the coming decades, under multiple pollution scenarios. The map allows users to examine affordable housing at risk by state, city, county, congressional district, state legislative district, or zip code. The web tool and report are available in English and Spanish. Access the tool at:
https://coastal.climatecentral.org/map/8/-74.7243/40.0852/?theme=flood_…

To access the report, webinar, peer-reviewed paper, web tool, and more details visit: https://www.climatecentral.org/news/report-coastal-flood-risk-to-afford…