From Miami Beach to Melbourne Beach, from Marco Island to Captiva, barrier islands are Florida’s postcard paradises.
They are also narrow strips of sand that, by definition, take the full brunt of hurricanes and storm surge, stand as sacrificial buffers for the mainland and rank among the state’s most precarious places to live. In their natural state, barrier islands are ephemeral.
Slowly but continuously, waves reshape their form. Over thousands of years, the sea has pushed them landward, a grain by grain migration from miles offshore to the edge of the coast. Their beauty eventually became visible — and increasingly irresistible — to humans.
And developers keep building on them and people keep moving to them in a building boom on land meant to wash away.
A Miami Herald analysis — the first comprehensive mapping of development across all of Florida’s barrier islands — found that these inherently unstable strips of sand are now home to nearly 765,000 residents, the most in the nation.
Between 2010 and 2023, Florida’s barrier island population grew an estimated 6%, even as climate risks worsened.
Today, many of Florida’s barrier islands have been engineered and expanded, sections elevated and armored to resist relentless nature.
The Herald’s data show these already densely populated sandbanks are growing skyward to pack in more people: A third of all housing on barrier islands is now in buildings with more than 50 units. For comparison, only about 9% of all housing in the entire state is in buildings with more than 50 units.
Some of these massive buildings are sinking more than engineers expected, according to a Miami Herald analysis of engineering records and a University of Miami-led study.
The exact reasons, consequences and risks of the settlement have yet to be investigated and though none of the experts the Herald interviewed pointed to any immediate safety concerns, the potential long-term impact on maintenance issues on properties could affect one of the area’s most vital economic sectors.
But sinking buildings isn’t the biggest risk barrier island communities face.
When hurricanes invariably loom, evacuation routes clog and a few residents refuse to leave — a choice that proved fatal in 2022, when more than 100 Floridians died, many swept away by surge on Southwest Florida’s barrier islands.
And erecting billions of dollars of real estate in harm’s way ultimately costs all of us.
The barrier island boom has often inflated hurricane damage, helping fuel Florida’s soaring property insurance rates and saddling taxpayers statewide with the growing tab for shoring up coastlines — from fortifying eroding beaches and restoring dunes to rebuilding roads, bridges and other expensive infrastructure.
In Sunny Isles Beach, high-rise towers The Bentley, right, and the St. Regis, left, near the coastline show how construction is increasingly taller on barrier islands throughout Florida. (Matias J. Ocner/Miami Herald)
‘Inherently risky and vulnerable’
Cross the bays that separate Florida’s 80 barrier islands from the mainland, and their allure becomes apparent.
Life seems to slow with the rippling rhythm of waves and caress of cooling breezes.
On some, you may even find sea turtles, struggling to make their way through the surf beneath a wide-open sky.
They are paradise — until hurricane season.
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And hurricanes hit Florida with inescapable regularity. Since 2000, the 10 worst alone left upwards of $200 billion in property damage and nearly 500 people dead.
Barrier islands, which protect more than half of Florida’s coast, suffered some of the worst scars.
Their landscapes were literally resculpted.
Storm surges, which can reach 17 feet or more, can easily wash over dunes and communities.
Ian, in just one example uprooted and moved whole townhouses and flooded homes and condos, filling them with beach sand along the Gulf Coast.
Just last year, Hurricane Helene ripped a 130-feet-wide inlet through an unpopulated part of the barrier island of Siesta Key.
“If this went through a residential area it would be real chaos — an absolute disaster,” said coastal scientist Stephen Leatherman, a professor at the Earth and Environment department at Florida International University and a leading barrier island expert.
Stephen Leatherman, coastal scientist and professor at FIU, helped the Miami Herald map the development on Florida’s barrier islands. (Carl Juste/Miami Herald)
And Florida has luckily avoided much worse scenarios.
In 2012, Hurricane Sandy tore several breaches through New York’s barrier islands, including a 1,500-foot gap off the coast of Long Island that cost $6 million to refill.
In 2003, Hurricane Isabel carved a 2,000-foot inlet through North Carolina’s Outer Banks.
With the highway washed out, locals were cut off for two months.
Though particularly wide barrier islands like Miami Beach are unlikely to be completely split, all barrier islands are “inherently risky and vulnerable,” Katy Serafin, who specializes in coastal flooding and erosion hazards at the University of Florida, told the Herald. “We don’t like that because we want stable places to live, but that’s just not what they are,” she says.
After all, she said: “They are made of sand, not rock — and sand is moveable.”
Locals walk past Midnight Pass, a naturally formed waterway that had been filled in with sand but reopened after Hurricane Helene, restoring the flow between the Gulf and Little Sarasota Bay. (Ashley Miznazi/Miami Herald)
No place to call home
When Florida’s Atlantic barrier islands first formed some 7,000 years ago, they were located tens of miles farther out at sea, invisible from the coast.
Once they had migrated into sight, native people knew that these islands were no place to call home.
At most, they saw them as fishing outposts.
But modern-day developers, tourists and buyers saw them as scenic escapes.
In the past 150 years, Florida has colonized many of them with gorgeous Art Deco hotels, cocktail bars just a few steps from the water and condos with sweeping views of the Atlantic and Gulf Coast.
The extent to which humans have now shaped and engineered Florida’s barrier islands became apparent when the Herald set out to track their growth.
No publicly available map even showed exactly where natural barrier islands end and man-made appendages begin. So — in a collaboration with FIU’s Leatherman — we created one, then overlaid them with the most up-to-date census data.
The mapping only underlined the risks of barrier island development. While the population grows, the islands shrink or shift.
Those beaches that draw so many people to barrier islands are also in a constant state of erosion, waves and tides scooping sand and depositing it down the coast or offshore.
It can happen incredibly slowly or, during hurricanes and storms, swiftly.
That didn’t matter until we began putting people and buildings on them and creating tourist meccas like Miami Beach.
By the late 1970s, the city had lost much of the sand that gave it its name. Hotels were left with a thin strip for tourists to sunbathe and, of more concern, a slender buffer from the forces of the Atlantic Ocean.
“There is really no erosion problem until people build on the shore. After this commitment has been made, there is a tendency to go to great lengths to protect this initial investment,“ Leatherman was already noting back in the 1980s in a book on coastal development.
Today, some 45 years later, it’s clear that those “great lengths” didn’t just include rebuilding entire beaches almost from scratch, but doing so over and over again.
No state excels at this Sisyphean creation of artificial beaches like Florida. In fact, almost every inch of the state’s barrier island beaches is now man-made.
Miami Beach’s first beach restoration was documented in 1979.
The so-called “renourishment” cost $60 million for a 10-mile stretch of beach.
Adjusted for inflation, each mile of beach cost close to $27 million in today’s dollars.
“This was the most extensive and expensive project undertaken anywhere in the world with the simple goal of placing sand on a beach,” Leatherman wrote in 1982.
It wasn’t the last.
Since then, American taxpayers have helped bankroll $130 million on a total of 49 such projects for Miami Beach — and it’s only the third-most expensive in Florida.
Both Cape Canaveral and Cocoa Beach with more than $170 million, and Sand Key in Clearwater, just north of St. Petersburg, with more than $140 million, all barrier islands, cost more.
In total, Florida has spent more than $2.3 billion on sand to preserve its constantly shifting shoreline.
That’s $800 million more than New Jersey, which spent the second-most on maintaining its beaches.
And the bill is set to rise: Each storm washes away the sand and the relative protection it offers to buildings, and while the U.S. Army Corps of Engineers shares costs and directs restoration projects, the future of funding is uncertain.
New sand is getting harder and harder to come by, as the sand left on the ocean floor isn’t fine or white enough, neither for tourists nor wildlife.
Today, sand is being trucked in from a mine in central Florida, at $30 – $50 a cubic yard.
It takes a lot of yards to restore even small sections of beach.
Miami Beach’s planners, politicians and civic leaders are among the most proactive and aware of the climate risks ahead, even making it part of marketing campaigns.
Beyond maintaining a massive beachfront buffer, the city designed 40-acre South Pointe Park and its beach walk to offer additional flood protection.
And one of the city’s biggest points of pride is the massive, vegetated dunes that alleviated flooding during Hurricane Irma.
“I always say we know about our risks, which is good — we don’t have our head in the sand,” Amy Knowles, the city’s chief resilience officer, told the Herald.
While such investments might be justifiable in densely populated, tourist-luring barrier islands like Miami Beach, research by coastal hazard protection experts like Eli Lazarus also shows that these defenses signal to the market that taxpayer dollars will be spent to protect their private properties on barrier islands.
As a result, he said, “you actually stimulate more growth in the lee of that protection.”
As far back as the 1980s, the federal government — then led by Ronald Reagan — took steps to tamp down barrier island building and protect taxpayers from footing the bill after disasters.
The Coastal Barrier Resources Act would eventually make some 3.8 million acres of barrier islands ineligible for federal flood insurance, discouraging development.
Studies since show that has saved taxpayers close to a billion dollars a year.
By that time, development on Miami-Dade’s barrier islands was already on steroids. Today, almost 30% of those high-density 50+ unit buildings on Florida’s barrier islands are located within Miami-Dade — from Key Biscayne to Sunny Isles.
Florida’s insurance crisis
But the biggest impact of the barrier island boom is reflected in your annual property insurance bill.
Virtually every home and property owner in the state pays more because of it.
Stricter building codes have reduced the threat to individual structures since Hurricane Andrew struck in 1992 but the sheer density and value of properties still multiply the potential losses.
Swiss Re’s wind perils lead Erik Lindgren projects that a similar hurricane making landfall in Miami-Dade would “likely exceed $200 billion in insured losses.”
That would make it the most expensive storm to ever hit the U.S. — double the cost of the current record holder, Katrina, even when adjusted for inflation.
“And Andrew isn’t even the worst-case scenario,” Lindgren said.
A storm with higher rainfall or a stronger surge in Florida wouldn’t just cause tremendous human and economic suffering locally, but could reverberate across the entire country because of intertwined insurances and mortgage markets, said Ishita Sen, an assistant professor of finance at the Harvard Business School.
“It’s just completely mind-blowing how crazy the numbers are,” said Sen, who testified about her research on the risks of Florida’s insurance market to a U.S. Senate committee last June.
Florida’s insurance crisis has been fueled by national firms fleeing the state because of hurricane risks, leaving coverage to the state-run Citizens Insurance or a string of small, underfunded companies.
In the face of actual disaster, about 20% of these Florida-based companies have folded — a rate 100 times higher than that for national insurers.
If a major storm like the one Swiss Re described were to sweep Miami-Dade and its barrier islands — packed with luxury high-rises — Sen estimates that about 30 local insurance companies would go under. Without their payouts, households would default on their mortgages.
“That is really, really bad news,” she said, “not only for the household, but for lenders and whoever’s exposed to those mortgages,” through Fannie Mae and Freddie Mac.
At some point, the ripple effects could reach Wall Street, but they begin on the waterfront thousands of miles south.
In a worst-case disaster, experts say, Florida’s gamble on its most fragile land — its barrier islands — could send shockwaves through insurance markets, mortgage systems, and ultimately, the national economy.
On the ground, though, city officials like Knowles, the Miami Beach resilience officer, see little choice but to keep adapting.
“Florida is in hurricane alley, whether you’re on the Gulf Coast or our coast — we have hurricanes, and we can’t just pick up and move,” she said. “So I think the decision has been made to protect and to adapt — to build better.”
This story was originally published by the Miami Herald and shared in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the Sun Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times.
