Report: Rising Sea Levels Threaten Affordable Housing

More than 7,600 apartments, townhomes, and houses nationwide are currently exposed to at least one “coastal flood risk event” in a typical year, and more than 24,500 units may be so threatened by 2050, according to a new report by The National Housing Trust and Climate Central. Their analysis evaluates the risk to affordable housing from flooding related to sea-level rise over the next 30 years. In short, the number of affordable housing units at risk from coastal flooding and sea level rise is expected to more than triple over the next three decades. A flood risk event occurs when local coastal water levels reach higher than a building’s ground elevation, and any known barriers don’t provide full protection.

According to the report, New Jersey has the highest number of units and percentage of its affordable housing stock exposed, followed by New York and Massachusetts. Fewer units are at risk in California, but these units face a high risk of repetitive flooding, similar to affordable housing in Maine, Maryland, Alabama, and Texas.

By 2050, under a continued high-carbon emissions scenario, the risk increases significantly, with the aggregate number of affordable housing units exposed annually more than tripling to 24,519 units. New Jersey could see nearly 7,000 units exposed, a four-fold increase; and New York and Massachusetts would continue to rank among the top three states for absolute and relative number of units exposed. Pennsylvania (792 percent), Florida (774 percent), and South Carolina (669 percent) face the largest percentage increase over the 2,000 baseline in units exposed.

The researchers also ranked the top 20 cities in terms of annual numbers of units exposed by 2050. These 20 cities account for three-quarters of all the affordable housing units at risk of coastal flooding across the United States, showing that coastal flood risk is highly concentrated. Cities in the Northeast and California are the most vulnerable, with New York City remaining the most exposed, with over 4,000 units at risk per year by 2050. Five cities in New Jersey ranked in the top 20, four of which (Atlantic City, Camden, Penns Grove, and Salem) are among the poorest urban areas in the country, with an average median household income of just $28,618 (in 2018 dollars). In a number of cities, more than half of the affordable housing stock is at risk in 2050, including Foster City, Calif. (100 percent), Crisfield, Md. (92 percent), Hoquiam, Wash. (72 percent), and Atlantic City (52 percent).