Report: Rising sea will flood $645 million worth of N.H. property

  • This photo was taken during a “king tide” in Portsmouth. Rising seas have contributed to an increasing number of king tides, a term for tides so high that they cause flooding even without a storm. Courtesy

Monitor staff
Published: 6/18/2018 12:01:09 AM

Hundreds of millions of dollars’ worth of property along the New Hampshire seacoast is likely to face damage from frequent flooding caused by rising sea levels within the next three decades, claims the latest report trying to quantify the effect of climate change on the nation’s coasts.

By 2045, about 2,000 New Hampshire residential properties home to about 3,000 people “are at risk of chronic inundation,” says the report issued Monday by the Union of Concerned Scientists.

“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,” the report says. These properties are worth $645 million today and pay about $9 million in annual property tax.

It notes that 2045 is within the time frame of a 30-year mortgage issued today.

The report’s risk calculations are based on a projected rise of 1.8 feet in sea level along the coast, which is the highest of three projections contained in the 2014 National Climate Assessment. If the ocean rises less than this, then the amount of damage and loss in property value would, of course, also be less.

The New Hampshire data is a small part the report’s estimate of sea level rise on the nation’s entire coastline. Titled “Underwater,” the report argues that “as sea levels rise, persistent flooding ... will render properties effectively unlivable. ... Yet property values in most coastal communities do not reflect this. And most homeowners, communities and investors are not aware of the financial losses they may soon face.”

This isn’t the first time a report has cautioned that New Hampshire coastal property is at risk as oceans rise due to melting ice and expanding seawater from rising temperatures. In 2016, the Coastal Risk and Hazards Commission, established by the state Legislature in 2013, released a report saying that rising sea levels will threaten much of the Seacoast by the middle of this century unless action is taken to control development and address the effects of climate change.

That report drew criticism from the brother of New Hampshire’s governor. Michael Sununu, a businessman, wrote a report issued through the Josiah Bartlett Center, a conservative think tank, arguing that the concerns were overstated and would lead to a waste of public money.

Rising seas have contributed to an increasing number of “king tides,” a term for tides so high that they cause flooding even without a storm. The New Hampshire Coastal Adaptation Workgroup has run a contest for king tide photos for a couple of years, gathering pictures of historically unusual high tides along the coast and in the Great Bay.

The Union of Concerned Scientists report released Monday defines “chronic inundation” as places that are flooded at least 26 times a year. It says it gathered data from tidal gauges along the east, west and Gulf coasts of the U.S., combined with elevation models of coastal properties. They used three scenarios for potential sea level rise from the 2014 National Climate Assessment; the high level estimates an increase of 6.6 feet in New Hampshire by the year 2100.

Sea level rise is not uniform around the globe. Many scientific models indicate that due to ocean currents and the effect of ice melting off Greenland, the sea-level rise will be higher along the Northeast coast than the global average.

To assess numbers and values of affected properties, the group said it used information from Zillow, an online real estate database company.

The Union of Concerned Scientists report argues that the U.S. should be preparing now for the financial repercussions of sea-level rise and the potential loss of billions of dollars in coastal property values.

Surface flooding isn’t the only problem that coastal communities can face as sea levels rise. A major concern along portions of the coast involves seawater seeping inland and infiltrating aquifers that were previously filled only by fresh water, harming private wells and potentially even public water supplies.

More information, including an interactive map, is available at the Union of Concerned Scientists website,

(David Brooks can be reached at 369-3313 or or on Twitter @GraniteGeek.)
David Brooks bio photo

David Brooks is a reporter and the writer of the sci/tech column Granite Geek and blog, as well as moderator of Science Cafe Concord events. After obtaining a bachelor’s degree in mathematics he became a newspaperman, working in Virginia and Tennessee before spending 28 years at the Nashua Telegraph . He joined the Monitor in 2015.

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