Oliver MilmanLast modified on Mon 24 Sep 2018 13.59 BST
After her house flooded for the third year in a row, Elizabeth Boineau was ready to flee. She packed her possessions into dozens of boxes, tried not to think of the mold and mildew-covered furniture and retreated to a second-floor condo that should be beyond the reach of pounding rains and swelling seas.
Boineau is leaving behind a handsome, early 20th-century house in Charleston, South Carolina, the shutters painted in the city’s eponymous shade of deep green. Last year, after Hurricane Irma introduced 8in of water into a home Boineau was still patching up from the last flood, local authorities agreed this historic slice of Charleston could be torn down.
“I was sloshing through the water with my puppy dog, debris was everywhere,” she said. “I feel completely sunken. It would cost me around $500,000 to raise the house, demolish the first floor. I’m going to rent a place instead, on higher ground.”
Millions of Americans will confront similarly hard choices as climate change conjures up brutal storms, flooding rains, receding coastlines and punishing heat. Many are already opting to shift to less perilous areas of the same city, or to havens in other states. Whole towns from Alaska to Louisiana are looking to relocate, in their entirety, to safer ground.
The era of climate migration is, virtually unheralded, already upon America.
The population shift gathering pace is so sprawling that it may rival anything in US history. “Including all climate impacts it isn’t too far-fetched to imagine something twice as large as the Dustbowl,” said Jesse Keenan, a climate adaptation expert at Harvard University, referencing the 1930s upheaval in which 2.5 million people moved from the dusty, drought-ridden plains to California.
This enormous migration will probably take place over a longer period than the Dustbowl but its implications are both profound and opaque. It will plunge the US into an utterly alien reality. “It is very difficult to model human behaviour under such extreme and historically unprecedented circumstances,” Keenan admits.
The closest analogue could be the Great Migration – a period spanning a large chunk of the 20th century when about 6 million black people departed the Jim Crow south for cities in the north, midwest and west.
By the end of this century, sea level rise alone could displace 13 million people, according to one study, including 6 million in Florida. States including Louisiana, California, New York and New Jersey will also have to grapple with hordes of residents seeking dry ground.
“There’s not a state unaffected by this,” said demographer Mat Hauer, lead author of the research, which is predicated on a severe 6ft sea level increase. There are established migration preferences for some places – south Florida to Georgia, New York to Colorado – but in many cases people would uproot to the closest inland city, if they have the means.
“The Great Migration was out of the south into the industrialized north, whereas this is from every coastal place in the US to every other place in the US,” said Hauer. “Not everyone can afford to move, so we could end up with trapped populations that would be in a downward spiral. I have a hard time imagining what that future would be like.”
Within just a few decades, hundreds of thousands of homes on US coasts will be chronically flooded. By the end of the century, 6ft of sea level rise would redraw the coastline with familiar parts – such as southern Florida, chunks of North Carolina and Virginia, much of Boston, all but a sliver of New Orleans – missing. Warming temperatures will fuel monstrous hurricanes – like the devastating triumvirate of Irma, Maria and Harvey in 2017, followed by Florence this year – that will scatter survivors in jarring, uncertain ways.