By Laura Paddison, CNN
(CNN) — New Orleans is locked into a watery future which could see it surrounded by ocean as early as this century, according to a new expert analysis, which says the city must start the relocation process now to avoid chaos.
The paper’s conclusions are stark, but it’s no secret that New Orleans is highly vulnerable to rising seas as the planet warms. Coastal Louisiana is one of the lowest lying regions in the world, and New Orleans, a city of 360,000 people, is particularly exposed. It sits in a bowl-shaped basin, mostly below sea level, in the middle of a rapidly shrinking delta.
The city is almost entirely surrounded by wetlands, which act as a buffer against hurricanes and storm surges. These are fast disappearing, however, as humans drain them for development, dredge canals in them for the oil and gas industry and construct river levees, depriving them of the sediments that stop them being submerged. Since the 1930s, Louisiana has lost around 2,000 square miles of wetlands.
Coastal Louisiana faces sea level rise of around 10 to 23 feet, according to the analysis published in May in the journal Nature Sustainability. The impacts will be bleak: around 75% of its remaining wetlands are set to be lost and its shoreline could retreat inland by up to 62 miles, the scientists found.
The region has “crossed the point of no return,” the paper’s authors wrote, adding New Orleans “may well be surrounded by the Gulf of Mexico before the end of this century.” They argue the city must seize the opportunity to develop strategies for relocation that could make it a model for places facing a similar fate.
Rising seas are coming for coastal towns and cities all over the world, from New York and London to Bangkok and Shanghai. “The main questions are how soon those futures will come, and how they will play out,” said Benjamin Strauss, CEO and chief scientist at Climate Central, a climate research nonprofit.
To map Louisiana’s future, the report’s scientists looked into its past. One of the authors identified an ancient shoreline roughly 30 miles north of New Orleans, which formed around 125,000 years ago when temperatures were similar to today, but the oceans were at least 10 feet higher.
“It’s very likely that sea level will rise to that elevation in the future,” said Torbjörn Törnqvist, a report author and a geology professor at Tulane University. The question is what should be done and when.
People are already leaving coastal Louisiana and have been for decades, said Brianna Castro, a study author and assistant professor of urban sustainability at Yale School of the Environment.
Since Hurricane Katrina — which slammed into Louisiana in 2005, killing nearly 1,400 people — New Orleans has lost around 25% of its population. The retreat has been a “pulse-like” process, where every major storm or flood prompts a spike in departures, Castro said.
The storms the city faces are only likely to get harder to endure. Approximately 99% of the population in New Orleans is at high flood risk, according to a recent study. “When another Katrina-like hurricane strikes the city, almost everyone would experience flood damages,” said Wanyun Shao, an author of that study and associate professor of geography at the University of Alabama.
Failing to implement a carefully managed relocation process risks a “chaotic” retreat which will come at a high cost, especially for the city’s poorest, the paper’s authors argue. As the popu