Can It Adapt to Rising Seas?
In the summer of 2014, a team of Dutch architects and engineers flew to Miami to show civic leaders how Miami Beach and other South Florida lowlands could be saved from rising seas that threaten to swamp them by mid-century.
A futuristic Miami Beach, as sketched out by the Dutch, would have buildings on stilts, water taxis chugging along canals, floating buildings, water storage ponds that double as lakes in parks, tall, grassy berms along the seashore to protect against storm surges, and giant gates to hold back the sea. The designers also considered this novelty of engineering: sealing the underside of the seven-mile-long island with bentonite to prevent seawater from bubbling up through the porous limestone bedrock on which most of South Florida was built.
The sealant idea was scrapped as absurd, even given the ingenuity of the Dutch, who have been protecting the Netherlands from the sea since the Middle Ages. They conceded it is virtually impossible to keep water from flowing through a foundation that is often described as Swiss cheese. Still, the notion that the region could be remade into one of the world’s great adaptive urban water landscapes presented possibilities too tantalizing to ignore – especially as Florida faces climate change, the greatest threat to its existence.
“Singapore, Copenhagen, Stockholm – these are all cities that emphasize their water identity and make it a sales objective. Miami could become a water city,” Piet Dircke, whose firm, Arcadis, helped New Orleans design new barriers after Hurricane Katrina, said at the time.
How to protect Miami from rising seas “is ultimately our existential question,” says Phil Stoddard, a biology professor at Florida International University and mayor of the suburb of South Miami.
Globally seas are projected to rise at least two feet by mid-century and as much as 6.6 feet by 2100, according to the National Climate Assessment. Scientists are now reconsidering those predictions as too conservative. In Florida, a two-foot rise would swamp most of the barrier islands, including Miami Beach, and strand key utilities, such as the nuclear power plant on Biscayne Bay. Six feet would put much of Miami-Dade County underwater – but the county would be in trouble long before. Hurricane Andrew, which hit South Florida in 1992, arrived with a 15-foot surge, which mostly stayed east of a ridge that runs down the state’s eastern side. A 15-foot surge on top of the two-foot rise in sea level would push water west over the ridge, all the way to the Everglades, inundating the entire county.
In the two years since the Dutch visit, South Florida has taken small steps toward adapting. Seawalls are being raised. Beaches have been renourished, wastewater plants constructed at higher elevations than their predecessors, and “living shorelines” of plants and animals erected to protect vulnerable places against storms.
Miami Beach, which considers itself the leader on this frontier, has taken more drastic steps. The city has spent more than $400 million to replumb aging storm sewers that, in theory, will prevent street flooding that already occurs routinely now at high tide. Seawalls and selected streets also are being raised. In his latest project, city engineer Bruce Mowry is trying to persuade developers that Miami Beach’s building of the future has a first floor with a variable height.
“The street may not be at the same elevation 75 years from now,” he says. “It’s hard for architects to grasp. They are used to building a building at a fixed level. That’s no longer going to be known. It’s a variable. What you have to do is make your building as flexible as possible to better adapt to whatever the sea level is.”
Yet at the same time, South Florida is entrenched in a spasm of building and new development that is putting millions of new construction in the very places that are most vulnerable to rising seas. Downtown Miami, for decades a wasteland of parking lots, government buildings, and a downtrodden shopping district, is being transformed into what some call a “new Manhattan” with condo towers, office buildings, and a slew of retail stores and restaurants. Yet it lies very near sea level, bordering on Biscayne Bay along its eastern boundary.
If these two story lines seem contradictory, well, welcome to Florida. In some ways, the boom is no change from Florida’s history, and Mowry is just the latest in a long line of engineers and visionaries who have been reshaping and rebuilding the landscape continuously ever since the founders drained the Great Swamp to the west, dredged canals and built fake lakes and fake islands and transformed South Florida into an international playground. At the turn of the last century, Miami Beach itself was just a swampy barrier island fringed on the west side with mangroves that housed crocodiles.
Yet this time, Florida may not be able to dredge its way out of its troubles.
Florida, with 1350 miles of coastline, remains one of the most-threatened places on Earth. A study published in March, 2016 suggested that the number of coastal dwellers in the United States at risk to inundation could be three times greater than previously estimated. That would put six million Floridians at risk.
Hal Wanless, a geology professor at the University of Miami long known as South Florida’s doomsday man for his predictions that all of South Florida will eventually be under water, says the effort to adapt Miami and its environs to its water future is understandable. But he cautions that plans must include mass migrations and cleansing the land left behind.
“Is it worth spending $500 million raising roads and sea walls or is it really a waste of money?” he asks. “We can’t waste all our money on defense. We have to be cleaning the land as it becomes inundated and we have to deal with relocation.”
That’s a hard sell this far out from calamity. Aside from the isolated spots that flood, South Florida, with its welcoming weather, blue skies, and pastel clouds tinged with pink, looks blissfully unthreatening and inviting today. Even Wanless has no plans to relocate.
“We’re going to live here as long as we can,” he says. “But we’re going to make sure we’re not investing in five properties for our grandchildren.”