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A new study predicts more "nuisance floodingin coastal areas across the United States, including Edisto and Kiawah islands. Kyle Simmons wades through water to check on the home of his grandmother following Hurricane Matthew on Edisto Island on Oct. 9, 2016. File/AP

In just 18 years less than the life of some mortgages rising seas will cause disruptive flooding in about 170 coastal communities across the United States, including Edisto and Kiawah islands, a new analysis says.

Prepared by the Union of Concerned Scientists, the study is said to be the first nationwide attempt to identify tipping points times and places where flooding is so frequent that residents abandon their land or pump big bucks into projects to hold back the ocean.

No stranger to high water, Charleston already sees regular nuisance floods at seasonal high tides, though the problem has grown worse in recent years. Charleston averaged four days of tidal flooding 50 years ago. Last year, the city had a record 50 flooding days, many when the sun shined.

Even so, the city has yet to reach a chronic inundation threshold when 10 percent or more of its usable, non-wetland area floods at least 26 times per year, according to the Union of Concerned Scientists report.

That will change within a couple of generations.

The Union of Concerned Scientists puts rigorous, independent science to work to solve our planet's most pressing problems. Joining with citizens across the country, we combine technical analysis and effective advocacy to create innovative, practical solutions for a healthy, safe, and sustainable future.

Source:ucsusa.org

By 2060, under moderate sea-rise scenarios, the group predicts 16 percent of peninsular Charleston will see debilitating floods at an average rate of every other week.

By then, chronic floods also will affect roughly:

The situation only grows worse after that, the report said.

By 2100, rising waters could swallow or routinely flood nearly 87 percent of Kiawah Island, 57 percent of Edisto Island, 40 percent of James Island, and about one-third of the Charleston peninsula and Mount Pleasant. This assumes that sea levels increase by 4 feet by the end of the century, which is in the mid-range of current scientific estimates.

With its low elevation and expansive marshes, the South Carolina Lowcountry is well-named. Even relatively small rises in the sea level can move water far inland.

In Lowcountry on the Edge, The Post and Couriers climate change series, the newspaper reported how 1 foot of rising water could flood 204,000 acres of marsh and 64,000 acres of land in Charleston County alone. This would affect nearly 1,000 homes, offices and other buildings, according to a College of Charleston geology department report.

Locally, the city of Charleston is spending or plans to spend about $300 million on drainage work and a future seawall in peninsular Charleston.

"We're already concerned" about sea rise, said Charleston Mayor John Tecklenburg, adding that he hasn't seen the report.

In addition to the drainage and seawall project, the city has been working on more specific sea-rise adaptation plans. Recommendations may be discussed at a public workshop later this month. He said the city likely will need to prioritize which land in the city should be protected from rising waters and which should be left to the waves.

You dont want create another flood problem by building in a flood plain.

South of Charleston, Kiawah Island Mayor Craig Weaver said the October 2015 storm and Hurricane Matthew in 2016 helped spur what he described as a low-key look at the islands vulnerabilities to sea rise. The town established a citizens committee earlier this year that should make recommendations later in 2017.

He said he didnt consider sea rise an urgent issue, adding that we are not wading into the broader political debate about global warming or its causes.

"They understand that if we fail to limit warming, were committing a great many people to a future of flooding and inundation."

- Rachel Cleetus, lead economist and climate policy manager at the Union of Concerned Scientists

The Lowcountry is by no means alone in its sea-level struggles.

About 270 communities face chronic flooding and possible retreat by 2060, the Union of Concerned Scientists report said. The report is called When Rising Seas Hit Home and was published Wednesday in the scientific journal Elementa.

Coastal Maryland and Virginia will be especially hard hit. In addition to rising sea levels, land there is subsiding sinking downward because of movements in the earth's tectonic plates. Louisiana's situation is even worse. Land there is subsiding in part because of efforts to reroute the Mississippi River. A football field of land in Louisiana now washes away every hour, scientists say.

Wednesdays analysis by the nonprofit comes at a time of high political tension about how to address a climate thats changing at a rapidly increasing pace.

The Trump administration recently pulled the United States out of the Paris climate accord, the international agreement to reduce greenhouse gases. Meantime, new reports have trickled out during the past month about potentially devastating melting trends in GreenlandandAntarctica.

The reports authors said that hundreds of coastal communities could be spared if world leaders follow the Paris accords guidelines to reduce carbon emissions and other greenhouse gases.

Despite the Trump administrations opposition, states and cities have vowed to uphold the Paris agreements goals in their jurisdictions.

They understand that if we fail to limit warming, were committing a great many people to a future of flooding and inundation, said Rachel Cleetus, lead economist and climate policy manager at the Union of Concerned Scientists.

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New study pinpoints sea rise hot spots, with Edisto and Kiawah islands caught in the crosshairs - Charleston Post Courier