Report: 2,000 NH homes worth $645m at risk of rising seas by 2045

Union of Concerned Scientists analysis sees 5,000 Seacoast homes endangered by 2100


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On the heels of a similar study with its own dire prediction, the Union of Concerned Scientists has issued a report that says accelerating sea level rise, primarily driven by climate change, is projected to have a major impact on the Seacoast.

According to the report, “Underwater: Rising Seas, Chronic Floods and the Implications for U.S. Coastal Real Estate,”

by 2045, about 2,000 residential properties in New Hampshire with a total 2018 value of $645 million are at risk of chronic inundation. By 2100, the total number of at-risk residential properties is predicted to top 5,000 with a 2018 value of $2.4 billion. 

New Hampshire has a patchwork of shoreline stabilization structures along of its coast, but few are designed to keep out higher tides, according to the report, which notes that the towns of Hampton, New Castle, Rye and Seabrook are particularly at risk.

The report finds that, nationally, as many as 311,000 coastal homes in the lower 48 states will be at risk of chronic flooding by 2045. Some 14,000 coastal commercial properties are also at risk during that time frame, the report states.

By the end of the century, 2.4 million U.S. homes and 107,000 commercial properties could be at risk.

The UCS report combines property data from the online real estate company Zillow with a peer-reviewed methodology developed by the UCS for assessing areas at risk of frequent flooding. 

Using three sea level rise scenarios developed by the National Oceanic and Atmospheric Administration and localized for this analysis, UCS said it determined how many residential and commercial properties along the entire lower 48 coastline are at risk of becoming chronically inundated from high tides – flooding on average 26 times per year or more (or the equivalent of once every other week) in the coming decades, even in the absence of major storms.

Sea level rise

Earlier this year, real estate data and analytics firm CoreLogic reported that some 9,700 Seacoast homes are at risk of storm surge flooding, and in a worst-case scenario reconstruction costs could total over $2.3 billion.

The firm said it prepared its storm surge report using a methodology that combines simulations and different types of data from several sources, including the National Oceanic and Atmospheric Administration (NOAA) and the United States Geological Survey, as well as data owned by CoreLogic.

The core results in the UCS report are from the high sea level rise scenario, a conservative projection to use when estimating risk to homes. This scenario projects an average of 1.8 feet of sea level rise for New Hampshire in 2045 and 6.6 feet in 2100. The analysis also projects how many properties might avoid such flooding if sea level rise is constrained through the achievement of the long-term temperature goals of the Paris climate agreement and if ice loss is limited.

The UCS report’s other projections for New Hampshire include:

 • By 2045, more than $645 million worth of residential property (based on today’s values) is at risk of chronic flooding. The homes that would face this flooding at the end of the century are currently worth about $2.4 billion.

 • Homes at risk in 2045 currently contribute about $9 million in annual property tax revenue to their municipalities. Homes at risk by 2100 currently contribute more than $33 million collectively in annual property tax revenue.

 • Hampton, New Castle, Rye and Seabrook are particularly exposed and are already taking steps to adapt to increasing tidal flooding, with actions that include incorporating coastal hazards and climate change risks into municipal plans, issuing permits allowing residents to park in lots for free during flooding, and additional funding for construction and flood studies. By 2045, nearly 1,500 Hampton homes - nearly 20 percent of all the homes in the community - are at risk of chronic inundation. Rye is also heavily affected, with nearly 200 at-risk homes in this time frame.

 • By 2045, more than 100 of today’s commercial properties in New Hampshire, currently assessed at about $77 million, would experience chronic inundation. In 2100, the number is expected to jump to about 350 properties, assessed at approximately $261 million today.

The report also notes that many current federal, state and local policies mask risk and create incentives that reinforce the status quo or even expose more people and property to risk.

The report cites the “market’s bias toward short-term decision-making and profits can also perpetuate risky development and investment choices.”

The report also calls out “flawed policies and incentives,” stating they include incomplete or outdated flood risk information, subsidized insurance, lax zoning and building codes, incentives for business-as-usual building and re-building and incomplete credit ratings. The report urges “identifying and improving upon the most important policies and market drivers of risky coastal development is a necessary, powerful way to better protect communities and move New Hampshire and the nation toward greater resilience.”

The UCS report, “Underwater: Rising Seas, Chronic Floods and the Implications for U.S. Coastal Real Estate,” includes an interactive mapping tool at arcqg.is.

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