A 6-meter dike? Miami threatened by climate change

MIAMI – Three years ago, shortly after Hurricane Irma left parts of Miami underwater, the federal government launched a study to find a way to protect the vulnerable South Florida coast from the tides. murderous and destructive storms.

The answer no one loves him anymore.

Build a wall, proposed by the US Army Corps of Engineers in their first draft of the study, currently under review.

Ten kilometers from him, in fact, mostly inland, running parallel to the coast through neighborhoods – except for a 1.5 km stretch directly on Biscayne Bay, past the glittering skyscrapers of Brickell, the city’s financial district.

The dramatic proposition of $ 6 billion it remains provisional and lasts at least five years.

But the surprising suggestion of a huge dam up 6 meters high crossing beautiful Biscayne Bay was enough for some Miamiians Pay attention.

The tough decisions that will be required to meet the city’s many environmental challenges are there, and few people want to make them.

“You need to have a conversation about, culturally, what our priorities are,” said Benjamin Kirtman, professor of atmospheric sciences at the University of Miami.

“Where do we want to invest? Where does that make sense?

“This is what I call generational problems “he added.

“And there is a huge reluctance to enter into this debate.”

In Miami, the United States metropolitan area which is perhaps the most exposed to sea level rise, the problem This is not a denial of climate change.

Not when hurricane season, which starts this week, returns with storms every year more intense and frequent.

Not when finding flood insurance has become increasingly difficult and unaffordable.

Not when the nights are so hot that leaving the house with a sweater to fight the nighttime cold is a thing of the past.

The problem is that the magnitude of the interconnected obstacles Those facing the area can seem overwhelming, and none of the possible solutions are cheap, easy, or pretty.

For its study, the Corps of Engineers focused on storm surgeIn other words, the rise in sea level which usually floods the coast during storms, and which has recently been aggravated by the greater intensity of hurricanes and the rise in sea level.

But that’s only one of the concerns.

South Florida, flat and low, rests on porous limestone, allowing the ocean to swell through the ground.

Even when there are no storms, the rising waters contribute to great tidal flooding, where the streets fill with water even on sunny days.

The expansion of salt water threatens spoil the underground aquifer the supply of drinking water to the region; and the cracking of old sewers and dilapidated septic tanks.

This leaves less space for the land to absorb the liquid, so the floodwaters linger longer and their runoff pollutes the bay and kills the fish.

And that’s just the rise in sea level.

Temperatures have become so sweltering in recent summers that Miami-Dade County has appointed a new “calo headr “acting.

“What you realize is that each of these issues, which are totally interconnected, are being addressed by different parts of government,” said Amy Clement, professor of atmospheric sciences at the University of Miami and chair of the resilience committee. climate change. city ​​of Miami.

“It’s divided in a way that makes it very, very difficult to move forward. And the bottom line is, it’s a lot more money than any local government has to spend. “

The state could help, up to a point.

Republican lawmakers, who have controlled the Florida legislature for more than 20 years, recognized in late 2019 that they ignored climate change for so long that the state had “lost a decade”.

They began to take steps to fund solutions, targeting more than $ 200 million in taxes, collected in real estate transactions, sea level rise and sanitation projects.

Lawmakers also designated $ 500 million in federal stimulus money for the fund.

However, the cost of everything that needs to be done runs into the billions.

The estimate for Miami-Dade County only for remove approximately 120,000 septic tanks It’s about $ 4 billion, and that doesn’t include the thousands of dollars every homeowner would have to shell out.

Enter the Corps, whose engineering projects, if funded by Congress, are covered 65% by the federal government and 35% by a local government sponsor.

No one wants to turn down a dime from Washington, but the proposal for a massive sea wall along one of Miami’s most scenic stretches has produced a rare moment of agreement between environmentalists and real estate developers, who fear damaging the delicate ecology of the bay and reduce property values.

“We were like, um,” said Ken Russell, the Miami city commissioner whose district includes Brickell.

“The $ 40 billion in assets you are trying to protect will be diminished if you build a wall around the center because you are going to affect market values ​​and quality of life.”

Other parts of the Corps of Engineers’ draft plan, which include storm barriers at the mouth of the Miami River and other waterways, are more attractive:

fortify water treatment plants and fire and police stations so that they can withstand the onslaught of seawater.

Raise or waterproof thousands of businesses and homes.

Plant mangroves, which can be a first line of defense against flooding and erosion.

Miami-Dade County wants all of these parties to come first; the final version of the plan is expected this fall.

There is still sensible point.

Among the houses he proposes to raise with taxpayers’ money, there are multi-million dollar mansions waterfront, the result of the Corps’ mandate to effectively protect as many lives and property as possible, which critics say inevitably leads to greater protection for the wealthy, whose possessions are worth more.

And then there are the walls.

Interior walls – some quite small, but others up to 3.9 meters high – would divide neighborhoods, leaving homes on the sea side with less protection.

The sea wall along Biscayne Bay, which could rise up to 20 feet and look as formidable as the noise walls along Interstate 95, would reverse decades of policies to prevent dredging and backfilling of the Bay.

For some critics, the plan dates back more than a century of dredging and pumping the Everglades Florida, which has given way to intensive agriculture and sprawling development, but ignoring the severe environmental damage the state continues to struggle with.

“I have a feeling that most Floridians would live with the risk of water to preserve their way of life,” said Cynthia Barnett, an environmental reporter from Gainesville, Fla., Who has published books on rain and the fate of the oceans. .

“This idea of ​​working with water instead of always fighting it is really the lesson of Florida history.

If Florida’s history has taught us anything, it’s that the fight against the water that defines us will bring hardship for generations to come. “

When local governments asked the public how they would like to deal with climate change, residents much prefer what is called green infrastructure: Layered coastal protection against a mix of dunes, sea grasses, coral reefs and mangroves, said Zelalem Adefris, vice president of policy and advocacy for Catalyst Miami, which works with low-income communities in the county .

“The Corps plan looks very different,” he said.

“It seemed really incongruous with the conversations going on at the local level.”

However, Army Corps officials say – in moderation – that they see no way around what they call structural elements.

The storm surge threat to Miami-Dade County is simplyand too serious.

“It’s going to be part of the solution,” said Niklas Hallberg, project manager for the studio.

He said the Corps is committed to working with the community in the next design phase of the project so that “it doesn’t look like such a big wall.”

It sounds like an approach to the vision that emerged from engineering consultants hired by Swire Properties, a large local developer, after the Corps’ draft plan alarmed the Downtown Miami Development Authority.

The consultants suggested building a berm of earth and rock that could rise even higher over time.

A landscape architecture studio hired by the Downtown Development Authority produced renderings of the Corps plan that showed dirty brown water in the bay and, yes, “Berlin” graffiti on the wall.

One recent afternoon, along the stretch of Brickell Bay Boardwalk Where the wall might go, Rachel Silverstein, executive director of Miami Waterkeeper, an environmental activism and research group, stood next to skyscrapers built right next to the water, calling them “a fundamental problem of Miami “because they leave the storm surge with nowhere to go. go

Silverstein is on the side of the supporters of structural elements more natural to fight against storm surges, such as strengthening the coral reefs, which would also bring ecological benefit to the bay.

He pointed to the bright blue-green bay.

“Instead of seeing this beautiful water, you would see a rough wall,” he said.

In front of her, a manatee came to take the air.

c. 2021 The New York Times Company