USA: Rising seas erode $15.8 billion in home value from Maine to Mississippi

Data scientists from First Street Foundation and Columbia University have expanded their peer-reviewed housing market research to include approximately 3.7 million coastal properties in Maryland, Delaware, and Pennsylvania, finding increased tidal flooding caused by sea level rise has eroded $862.1 million in relative property values between 2005 and 2017. This section of the Mid-Atlantic completes the researchers’ analysis of the Eastern Seaboard, bringing the total loss among all 15 East Coast states, Alabama, and Mississippi to $15.8 billion. The Foundation’s previous research has been reported by The Boston Globe, CBS Moneywatch, The Wall Street Journal, Bloomberg, Axios, The Washington Post, and The Christian Science Monitor.

Mid-Atlantic data

Among the three latest states analyzed, coastal properties in Maryland were hit hardest, losing $555.7 million in relative appreciation. Properties in Delaware saw $299.5 million in unrealized value, followed by Pennsylvania at $10.1 million. Researchers also analyzed Washington D.C., which showed minimal impact. One of the region’s hardest hit properties, a single family home on East Side Drive in Rehoboth Beach, lost $481,258 over the 12 year study period (see Mid-Atlantic: State Rankings, Hardest Hit Cities, and State by State Analysis).

17 - State analysis

Among the 17 states analyzed to date, Florida has seen the greatest loss in relative home values at $5.4 billion, followed by New Jersey at $4.5 billion, and New York at $1.3 billion. Ocean City, New Jersey; Miami Beach, Florida; and Charleston, South Carolina saw the greatest losses in relative property value (see East and Gulf Coasts: State Rankings, Hardest Hit Cities, and State by State Analysis).

Flood iQ

Coastal homeowners can learn how much relative value their personal property has lost on Flood iQ's website. The interactive flood visualization tool also shows current inundation estimates for frequent and highest annual tidal floods, as well as hurricane storm surge, and how those levels are projected to increase over the next 15 years. The website is the first publicly available database that gives coastal residents, homeowners, and prospective homebuyers access to comprehensive flood risk and property value loss information. 

Research and methodology

Steven A. McAlpine, Head of Data Science at First Street Foundation, and Dr. Jeremy R. Porter, a Columbia University professor and First Street Foundation statistical consultant, first established their peer-reviewed methodology with an analysis of the Miami-Dade County real estate market. That study, published in the journal Population Research and Policy Review, showed $465 million was lost from 2005 to 2017 due to sea level rise flooding. McAlpine and Porter have since created 18 housing market-specific models. By analyzing approximately 13.3 million real estate transactions, and applying the results to 25.6 million properties, the researchers have found a $15.8 billion loss in home value appreciation across 17 states.

“From Maine to Florida and through the Gulf Coast, we have seen the same phenomenon,” said Porter. “Increased tidal flooding has led to a loss in home value appreciation. We expect this trend to not only continue in the coming years, but to accelerate along with the accelerating rate of sea level rise.” 

McAlpine and Porter’s research is the first to quantify the observed negative impact of increasingly frequent tidal flooding, driven by sea level rise, on the housing market. Other models have forecasted the future impact of sea level rise flooding on coastal properties, but this is the first to demonstrate value loss that has already occurred. By taking into account characteristics associated with home value, such as square footage and proximity to amenities, and accounting for economic trends like the 2008 housing recession, the scientists were able to isolate the impact that increased frequent tidal flooding caused by sea level rise has had on home value. While most of the affected homes appreciated in value over the studied period, they did so at a significantly lower rate than comparable homes unaffected by tidal flooding. The research is also the first to find that in addition to direct property-lot flooding, nearby road flooding also has a major impact on home value. 

“This is critical information for people in coastal areas because it contextualizes the cost-benefits of personal and municipal adaptation measures,” said McAlpine. “It also empowers people to make informed decisions when buying or selling a home.” 

Matthew Eby is the Executive Director of First Street Foundation.

“Flooding is the costliest natural disaster in the United States,” said Eby. “FEMA is the gold standard when it comes to Americans understanding their flood risk, yet FEMA’s flood maps are fundamentally wrong. First Street Foundation’s home value research is the first step toward our goal of providing accurate, meaningful, and comprehensive flood risk information to every American.”