Report: Coastal Flooding Likely to Worsen by 2045

COURT HOUSE – A report issued this month, examines the future of coastal communities in expectation that rising sea level will cause more tidal flooding. Cape May is among 52 cities listed on the East and Gulf coasts that are likely to experience increased flooding over the next 30 years.
The 76-page report by the Union of Concerned Scientists, based in Cambridge, Mass., “Encroaching Tides,” is available above and online at www.ucsusa.org. It was co-authored by Erika Spanger-Siegfried, Melanie Fitzpatrick, and Kristina Dahl.
The following are excerpts:
“An analysis of 52 tide gauges in communities stretching from Portland, Maine to Freeport, Texas shows that most of these communities will experience a steep increase in the number and severity of tidal flooding events over the coming decades, with significant implications for property, infrastructure, and daily life in affected areas.
“Sea level rise, driven primarily by global warming, is the main cause of observed increases in tidal flooding. While global sea level rose roughly eight inches from 1880 to 2009, much higher rates have occurred along parts of the East Coast, including New York City (more than 17 inches since 1856), Baltimore (13 inches since 1902), and Boston (nearly 10 inches since 1921),” the report continues.
“By 2030, more than half of the 52 communities studied are projected to experience, on average, at least 24 tidal floods per year in exposed areas, assuming moderate sea level rise projections. Twenty of these communities could see a tripling or more in tidal flooding events.
“The mid-Atlantic coast is expected to see some of the greatest increases in flood frequency. Places such as Annapolis, Maryland and Washington, D.C. can expect more than 150 tidal floods a year, and several locations in New Jersey could see 80 tidal floods or more.
“As sea level rises, many tidal flooding events will shift from being minor to more extensive, with accompanying increases in disruptions and damage.
“By 2045, many coastal communities are expected to see roughly one foot of sea level rise. The resulting increases in tidal flooding will be substantial and nearly universal in the 52 communities analyzed.
“One-third of the 52 locations would face tidal flooding more than 180 times per year. Nine locations, including Atlantic City and Cape May, New Jersey could see tidal flooding 240 times or more per year.
“A growing proportion of these floods would be extensive, and as floods reach farther into communities, they would also last longer. Flood-prone areas in five of the mid-Atlantic communities studied could be inundated more than 10 percent of the time.
“As the reach of the tides expands, communities now largely unfamiliar with tidal flood conditions will be forced to grapple with chronic flooding — a new normal. Many of the studied locations that today see fewer than five tidal floods per year could see a 10-fold increase in the number of floods annually by 2045.
“Increased tidal flooding is essentially guaranteed. Changes already set in motion by our past and present heat-trapping emissions will largely drive the pace of sea level rise and flooding over the next several decades.
“Coastal communities must act with urgency to prepare for this rising threat — and there are many things we can do to help ensure enduring coastal communities.
“Municipalities, with state and federal help, should prioritize and incentivize flood-proofing of homes, neighborhoods, and key infrastructure; curtail development in areas subject to tidal flooding; consider the risks and benefits of adaptation measures such as sea walls and natural buffers; and develop long-term plans based on the best available science.
“The costs and challenges, however, are too great for municipalities to shoulder alone. A coordinated, well-funded federal response is also needed and should include both substantial investments in coastal resilience building, as well as action to deeply and swiftly reduce global warming pollution. This latter action may ultimately be the only reliable way to protect coastal communities over the long term – by slowing the pace of future sea level rise.
“There is a hard truth about adaptation, however. It has fundamental limits — whether physical, economic, or social — and it can only fend off the impacts of sea level rise to a point.
“As sea level rises higher, even our best protection efforts will not suffice in some areas in the face of rising tides, waves, and storm surges.
“If it reaches limits of coastal adaptation, a community will face the prospect of shifting back from heavily impacted areas. These limits will arrive sooner in those areas exposed to greater risks, those with more fragile ecosystems and limited natural buffers, and those that are less well-off economically.
“Leaders at all levels of government need to take seriously the risks facing people living along our coasts and the urgent need for action. We must prepare our communities for encroaching tides and other impacts of sea level rise even as we make a concerted effort to reduce the heat-trapping emissions that will determine the rate at which the ocean rises over the long term.
“In this future, days without high-tide floods could start to become the exception in certain places. Without sensible preparation for these disruptions, conducting daily life in such flood-prone areas would become, at best, unreliable and, at worst, dangerous.
“Relatively few of the 52 locations we analyzed on the East and Gulf Coasts now face minor or moderate tidal flooding on a regular basis. But by 2045, sea level rise will bring more tidal floods to nearly every location. Nearly 70 percent of these communities can expect tidal floods to at least triple in frequency by 2030 (bottom left). Charleston, S.C., Reedy Point, Del., and Sandy Hook, could average more than 75 tidal floods per year by 2030, while Cape May, Wilmington, N.C., and Annapolis, Md., could average more than 120.”