When Hurricane Sandy slammed into New York City in October 2012, floodwaters swallowed subway tunnels, destroyed thousands of homes, and killed 43 people across the city. More than a decade later, a peer-reviewed study published in Science Advances concludes that roughly half of New York City’s population, approximately 4.4 million people, now lives in areas exposed to extreme flood damage. The finding, drawn from an analysis of coastal cities stretching from Texas to Maine, places New York alongside New Orleans as the most at-risk major city on the U.S. Gulf and Atlantic coastline.
What the research found
Researchers evaluated 16 distinct risk factors, including building age, elevation, proximity to the coast, and prior flood losses, and ran the data through three separate artificial intelligence models to estimate exposure across dozens of U.S. coastal cities. Rather than relying on theoretical projections alone, the team anchored its analysis in FEMA’s historical damage database, which catalogs documented losses from past flood events.
New York City’s combination of dense population, aging infrastructure, and low-lying geography pushed it to the top of the risk rankings. According to the Associated Press, the study singled out New York and New Orleans as facing the most alarming profiles among all cities examined. Where a smaller coastal town might lose scattered properties, New York stands to lose entire neighborhoods’ worth of housing, transit lines, and commercial corridors in a single extreme event.
The underlying dataset, hosted on the Dryad research repository, is open-access, meaning independent researchers and city planners can verify the inputs and test their own models against the same baseline. That transparency matters. Flood risk assessments often depend on proprietary insurance models that local governments cannot interrogate, limiting their ability to contest premiums or design targeted protections.
Why coastal flooding keeps getting worse
A separate study published in Nature, titled “Sinking coastal cities” and led by Virginia Tech geoscientist Leonard Ohenhen and colleagues (2024), helps explain the mechanics behind the worsening trend. Land subsidence, the gradual sinking of ground surfaces, is compounding sea-level rise along the Eastern Seaboard. The study found that cities such as New York, Baltimore, and Norfolk are subsiding at rates of roughly 1 to 2 millimeters per year in some areas, with localized spots sinking faster, a pace that can effectively double the relative impact of ocean rise on the ground. Even modest increases in absolute sea level translate into significantly larger flood zones when the land beneath buildings and roads is simultaneously dropping…