According to a recently published in the journal PNAS, some 1,700 cities in the United States coastal areas are under threat of becoming swept by water as a results of rising sea levels due to climate change. The list of threatened communities spans Sacramento, California – which lies far from the sea but would be vulnerable to flooding in the San Joaquin delta – and Norfolk, Virginia. The most endangered municipalities are Miami, Virginia Beach and Jacksonville.

Hundreds of new cities of Atlantis

Previous studies have found that each 1 degree Celsius increment in global temperature would  lead eventually to 2.3m of sea-level rise. Factoring this and current rate of carbon emissions (an optimistic assumption since the trend has been upward for decades and hasn’t been down once), researchers at  Climate Central, a non-profit, non-advocacy research group based in Princeton, N.J., that’s funded by foundations, individuals and federal grants, found that 1,700 locations will be “locked in” by greenhouse gas emissions built up in the atmosphere by 2100.

“Locked-in” is the main keyword here. The whole study is based on the idea that even through some sort of miracle if tomorrow all anthropomorphic carbon emission would grind to a halt completely, the damage done up to that point is still irreparable. Carbon dioxide is trapped inside the atmosphere for centuries, so by virtue of climate inertia some locations have their faith already sealed – like 316 municipalities, but the timing when these will fall under sea-level is unclear and could take hundreds of years.

“Hundreds of American cities are already locked into watery futures and we are growing that group very rapidly,” said Benjamin Strauss, a researcher at Climate Central, and author of the paper. “We are locking in hundreds more as we continue to emit carbon into the atmosphere.”

Most coastal cities in the world under major threat for coming century

He says these sea levels are much higher than what’s predicted this century — typically 1 to 4 feet — because climate change multiplies their impact over hundreds of years. For the study, a location was deemed “under threat” if 25% of its current population lives below the locked-in future high-tide level. Some 1,700 places are at risk in this definition. Even if bar is set higher, at 50% of the current population, 1,400 places would be under threat by 2100.

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Climate Center has an interactive map where you can see what US states and specific municipalities are under threat by rising sea levels.

“This is probably the most unique and novel way I’ve seen of talking about a longer time frame,” says Peter Ruggiero, a coastal engineering scientist at Oregon State University.

Florida is the most vulnerable state by far, Strauss says, adding that Louisiana, New Jersey and North Carolina also face enormous difficulties. Unless major change occurs, he says, more than 100 cities in each of these states could be threatened. Some of these locations are home to navy bases, like Norfolk, Virginia where America’s largest navy base is sited, whose miles of waterfront installations would be at risk of being locked in to future sea level rises by the 2040s.

 “The current trend in carbon emissions likely implies the eventual crippling or loss of most coastal cities in the world,” writes Strauss, who directs Climate Central’s program on rising sea levels.

The authors of the paper advise as solutions to drastically cut down on CO2 emissions in the coming decades and massively deploy carbon capture technology that would suck CO2 from the atmosphere.

“Pretty much everywhere it seems you are going to be under water unless you build a massive system of dykes and levees,” Strauss said

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