By Oliver Milman
The process of relocating people from New Orleans
should start immediately, as the city has reached a “point of no
return” that will see it surrounded by the ocean within decades due to
the climate crisis, a stark new study has concluded.
Ongoing sea-level rise and the rampant erosion of wetlands in southern Louisiana
will swallow up the New Orleans area within a few generations, with the
new paper estimating the city “may well be surrounded by the Gulf of
Mexico before the end of this century”.
Low-lying
southern Louisiana faces multiple threats, with rising sea levels
driven by global heating, compounded by strengthening hurricanes, also a
feature of the climate crisis, and the gradual subsidence of a coastline that has been carved apart by the oil and gas industry.
Southern Louisiana is facing 3-7 metres of
sea-level rise and the loss of three-quarters of its remaining coastal
wetlands, which will cause the shoreline “to migrate as much as 100km
(62 miles) inland”, thereby stranding New Orleans
and Baton Rouge, according to the study, which compared today’s rising
global temperatures with a period of similar heat 125,000 years ago that
caused a rise in sea level.
This scenario
makes the region the “most physically vulnerable coastal zone in the
world”, the researchers state, and requires immediate action to prepare a
smooth transition for people away from New Orleans, which has a population of about 360,000 people, to safer ground.
Louisiana has already experienced population loss
in recent years, and this trend will accelerate in a disordered way,
the paper warns, should no action be taken to confront the perils faced
by its largest city and surrounding communities.
“While
climate mitigation should remain the first step to prevent the worst
outcomes, coastal Louisiana has evidently already crossed the point of
no return,” added the perspectives paper, published in the Nature Sustainability journal. A perspectives paper is a scholarly article that provides an assessment, rather than new data.
Billions
of dollars have been spent to fortify New Orleans with a vast network
of levees, floodgates and pumps erected after 2005’s catastrophic
Hurricane Katrina. But the growing threats to the city mean the levees,
which already require hefty upgrades to remain sufficient, will not be able to save the city in the long run, the new paper warns.
“In paleo-climate terms, New Orleans is gone; the question is how long
it has,” said Jesse Keenan, an expert in climate adaptation at Tulane
University and one of the paper’s five co-authors.
Keenan said the timeframe available to plan a retreat isn’t certain but “it’s most likely decades rather than centuries”.
“Even
if you stopped climate change today, New Orleans’s days are still
numbered,” he added. “It will be surrounded by open water, and you can’t
keep an island situated below sea level afloat. There’s no amount of
money that can do that.”
City, state and
federal leaders should begin work to help support people moving away
from the New Orleans region in a coordinated way, starting with the most
vulnerable communities, such as those in Plaquemines parish who live outside the levee system, Keenan said.
“New
Orleans is in a terminal condition, and we need to be clear with the
patient that it is terminal,” he said. “There is an opportunity for
palliative care, we can transition people and the economy. We can get
ahead of this.”
But, he added, “no politician
wants to first give this terminal diagnosis. They will speak about it
behind closed doors, but never in public.”
New
Orleans faces obvious challenges – situated in a bowl-shaped basin
below sea level, the city already has 99% of its population at major
risk of severe flooding, the worst exposure of any US city according to a separate study released last week.
“Even
compared to all other US cities, New Orleans really stands out, which
is alarming,” said Wanyun Shao, a co-author of this study and a
geographer at the University of Alabama.
“There
is no specific timeline to how long New Orleans has left but we know
it’s in big trouble. They are facing one of the highest sea level rises
in the world and I don’t know how long human effort can fight against
that tide. It’s like a timebomb.”
Shao said
she concurred that relocation of people would have to take place. “I
know it’s a politically and emotionally charged issue, there are people
with a deep attachment to New Orleans,” she said. “But managed retreat,
no matter how unappealing it may be, is the ultimate solution at some
point.”
A major pressure upon this southern
cultural hotspot is that its surrounding land is briskly receding. Since
the 1930s, Louisiana has lost
2,000 sq miles of land to coastal erosion, equivalent to the size of
Delaware, with a further 3,000 sq miles set to vanish over the next 50
years. The rate of land loss is so rapid that a football pitch-sized
area is wiped out every 100 minutes.
To help counter this, Louisiana
last decade settled upon a new sort of plan that eschewed building yet
more flood defenses and instead sought to harness the Mississippi
River’s natural ability to rebuild land. Levees and other infrastructure
have, until now, straitjacketed the naturally meandering Mississippi
and pushed the sediment it carries straight into the Gulf of Mexico,
rather than replenish the coastal wetlands.
The so-called Mid-Barataria Sediment Diversion
project, which broke ground in 2023, would help restore a more natural
flow in the Mississippi Delta and allow sediment to build up in coastal
areas where it has been lost. More than 20 sq miles of new land would be
created over the next 50 years under the plan, the project estimated.
However, Jeff Landry, Louisiana’s Republican governor, scrapped
the project last year, arguing its $3bn cost was too high and that it
threatened the state’s fishing industry. “This level of spending is
unsustainable,” Landry said at the time, adding that the project
imperiled the livelihoods of “people who have sustained our state for
generations”.
Proponents of the project, which
was funded via a settlement from BP over the Deepwater Horizon disaster
in 2010, decried the decision as disastrous for the state, pointing out
fishing communities will need to move anyway because of worsening
erosion.
Garret Graves, a Republican former congressman who once led the state’s coastal restoration agency, said
Landry was guilty of a “boneheaded decision” that would “result in one
of the largest setbacks for our coast and the protection of our
communities in decades”.
According to the new
research paper, the loss of the sediment diversion plan “effectively
means giving up on extensive portions of coastal Louisiana, including
the New Orleans area”.
A
legal effort to force oil and gas companies to pay for damage to
Louisiana’s coastline, meanwhile, is also in doubt. This month, the US
supreme court allowed the fossil fuel industry
to federally contest a state jury decision that Chevron pay $740m to
remedy harm caused to wetlands by dredging canals, drilling wells and
dumping wastewater.
“The combination of these
decisions is driving a scenario where the state has stopped trying to
build land,” Keenan said. “That just accelerates the timeline. They
could be buying time, but that option is foreclosed now, meaning it’s a
certainty the New Orleans levees will fail again multiple times. The
flood water will have nowhere else to go.”
While
the US has never wholesale moved a major city before, numerous
communities have relocated for economic reasons in the past, with some
now being shifted due to the climate crisis, too.
In Louisiana, the government could start planning and building
appropriate infrastructure in safer areas on the other side of Lake
Pontchartrain, the large estuary that sits to the north of New Orleans,
Keenan said.
“This could be an opportunity for
New Orleans to help migrate people further north, invest in long-term
infrastructure and make that sustainable,” Keenan said.
“That
exodus has already begun, so if nothing is done, people will just
trickle out over time and it will be an uncoordinated mess. The market
will speak as people won’t be able to get insurance. Louisiana has to
stop the bleeding and acknowledge this is happening. But at the moment
there is no plan.”
Timothy Dixon, an expert in
coastal environments at the University of South Florida who was not
involved in the new paper, said the study “does a nice job” of
highlighting the challenge Louisiana faces with subsiding land combined
with rising sea levels.
“New Orleans is not
going to disappear in 10 years or anything like that, but policymakers
really should’ve thought about a relocation plan a century ago,” said
Dixon, whose own research has recommended a measured retreat from coastal Louisiana.
“Governments
may not have the ability to just command people to leave, but people
will volunteer to move and we are seeing that already. I’m not
optimistic our political system is capable of dealing with this stuff,
it will take leadership and unpopular decisions. Also, many people don’t
want to move. They love where they are born.”
Landry’s office was contacted for comment but did not respond.