When a study in May concluded that New Orleans has hit a “point of no return” due to the climate crisis, the local reaction was swift and fiery - because nothing says resilience like yelling at a scientist.

Helena Moreno, New Orleans’ mayor, called the study “more focused on generating publicity and clickbait headlines” than solutions, noting that Miami floods and San Francisco burns, yet no one declares them lost causes. Gordon Dove, head of Louisiana’s coastal restoration agency, was less diplomatic: “I don’t think he knows what he’s talking about,” he fumed about lead researcher Torbjörn Törnqvist. Some locals posted defiant videos near levees with captions like “STOP TELLING US TO MOVE,” while others decried climate denial by state and federal governments.

Törnqvist, a Tulane University academic and leading expert on the Mississippi Delta’s fraying marshlands, says most locals who reached out were actually constructive. “Of course it’s upsetting,” he said, “but cities like New Orleans have an expiration date.” He warns that the Louisiana coastline could move as much as 62 miles (100km) inland within a century, turning New Orleans into “a fortress in the Gulf of Mexico… like Venice.” The cancellation of a $3bn project to revive the vanishing coastline by Louisiana’s Republican governor Jeff Landry, Törnqvist argues, is a further “death penalty” for the city.

Relocation of a city this size is unheard of in the US, which has no national strategy for climate-displaced people. New Orleans is already shrinking - now at just over 360,000 people - due in part to some of the highest home insurance rates in the country. Steve Picou, a musician and environmental planner, moved from New Orleans three years ago after his annual insurance jumped from $900 to about $9,000. “We are an indicator species,” he said. “Soon, other people are going to have stranded real estate assets.”

A loose coalition of community groups has started scouting potential escape routes: Vicksburg and Natchez, both in neighboring Mississippi, about three hours away. Debra Campbell, chair of A Community Voice, said residents in those cities welcomed the idea of an influx. “We’re coming in an exodus,” she said. “Nobody wants to leave home, but there may come a time where we can’t return.”

According to data from property intelligence company Cotality, New Orleans has the highest hazard risk in the country - a score of 100 based on floods, storms, and other perils. That’s 25 points higher than Natchez and Vicksburg, and double that of inland cities like Montgomery, Alabama. Howard Botts, Cotality’s chief scientist, explained: “The city is essentially a bowl surrounded by levees, and water will accumulate within that.”

Yet the defenses have held since Katrina. The Lake Borgne Surge Barrier - a 1.8-mile-long concrete and steel structure with 25ft yellow boom gates - has repelled hurricanes like Ida in 2021. Jeff Williams, regional director of the Southeast Louisiana Flood Protection Authority, believes the federal government won’t let New Orleans drown. “I don’t believe it’s a lost cause,” he said. “Technology has changed. Engineering has changed.” Still, another $1bn is needed to raise levees sinking into soft soils.

AR Siders, an expert in coastal relocation at the University of Delaware, worries about slow death. “There is no blueprint at all for this,” she said. “My fear is that a lot of US towns are facing a slow demise… We are all sitting around hoping someone else will solve the problem later on.”

For now, New Orleans clings to its jazz, Mardi Gras, and Creole culture - and to the hope that investment, not retreat, is the answer. “We need investment,” said Arthur Johnson of the Lower Ninth Ward. “If you talk about leaving, it can be an excuse to not have economic development. Where do you move anyway?”