Days after hurricanes Irma and Maria tore through Puerto Rico in 2017, Ernesto Diaz formed a team to survey what the Category 5 storms had done to his home. Touring coastal areas, Diaz, then an assistant secretary with the commonwealth’s Department of Natural & Environmental Resources, saw rooftops poking out from floodwaters, forests stripped bare, and windows and doors floating by. As a marine scientist who knew the shoreline ecosystems intimately, he also noticed something that intrigued him: Communities near coral reefs sustained less damage.
That became the genesis of a first-of-its kind project when, in 2022, the Federal Emergency Management Agency gave Puerto Rico $38.6 million to shore up its ailing reefs. It’s the first time the agency has tapped its Hazard Mitigations Assistance Grants program, which spends hundreds of millions of dollars each year to help communities rebuild after disasters, to fund such restoration. Diaz has since moved to Tetra Tech, the contractor implementing the first phase of the effort. “I hope this is the pilot project for what I believe should be the way we protect coastal communities, infrastructure, and beaches,” he said. “Everybody sees it. Everybody knows that’s our guardian.”
It’s not an exaggeration to say coral reefs face an existential threat from climate change. An average global temperature rise of 1.5 degrees Celsius (2.7 degrees Fahrenheit) would by one estimate likely wipe out 70 to 90 percent of them. In November, scientists said overheating seas, pollution, disease, and other abuses have already pushed some 40 percent of coral species to the edge of extinction.
For decades, conservationists have begged to save these vibrant ecosystems, arguing it’s the right thing to do. Coral reefs nurture about a quarter of all marine life, drive coastal economies, and provide food and livelihoods to a wide swath of the population. Each year, public and private entities provide about $300 million for reef protection worldwide, a fraction of the billions their advocates long for. “For a long time it’s been a reliance on philanthropic dollars,” said Emily Kelly, blue carbon lead at the World Economic Forum. “There hasn’t been a business case for investing in coral reefs necessarily.”
Over the past decade, a small group of U.S. government and university scientists have compiled a body of work making just such an argument for their care. In rigorously modeled, peer-reviewed work, they’ve shown that coral reefs protect tens of thousands of people and billions’ worth of economic assets every year. They and others increasingly argue that if coral reefs are effectively high-performance seawalls, they should be maintained and strengthened with federal disaster funds — purses tens to hundreds of times larger than conservation budgets. Their math has already inspired pilot projects funded by FEMA, the Department of Defense, and insurance giants Swiss Re and Munich Re, each based on the logic that if we won’t protect corals for their sake, we’d better do it for ours.
“It’s kind of a selfish way to look at these ecosystems. We need to maintain them because they’re protecting people,” said Borja G. Reguero, a coastal engineer and professor at the University of California, Santa Cruz who’s co-authored much of the relevant science. Such logic is compelling to the emergency authorities and insurance companies that wind up “paying for the Katrinas and Sandys,” he added.
That coral reefs, in addition to being majestic creations, shelter coastlines is an understanding embedded in the practices of many indigenous peoples. In Polynesia, for example, communities build closer to shorelines buffered by reefs than those that are not, said James Hench, a physical oceanographer and professor at Duke University’s Nicholas School of the Environment who’s done extensive fieldwork there.
Scientists have long understood this as a general principle. Individually, corals are small polyps, but together they form wall-like structures with a porous, complex surface. In the right location — close to shore, or near the water line — a reef provides a speed bump for waves and storms, dissipating their energy. The effect is sometimes dramatic enough to see from land: Stand on a beach in San Juan, Diaz says, and you’ll easily spot the white froth of waves breaking 4,600 feet offshore.
Yet no one had ever precisely quantified the benefit of this, let alone at a level sufficient to change policy. About eight years ago Curt Storlazzi, a research geologist with the U.S. Geological Survey, or USGS, started chatting with Mike Beck, a marine scientist then employed by The Nature Conservancy, about how to change that. They felt that the little science available at the time was too general to grab the attention of the government and insurance companies. To win their support, Storlazzi said, they needed to show in excruciating detail how corals protect “dollars and lives.”
To achieve that, Beck and Storlazzi gathered a team of scientists from within and beyond the government. They set out to build, from scratch, a model that set aside the many valuable attributes of America’s 1,900 miles of coral reefs and quantify only their performance as flood barriers. This required an exhaustive merging of disciplines, with the aim of simulating wave physics, under different storm scenarios, for every 10 meters, or roughly 33 feet, of coastline with a reef — and understanding just who and what was on the shoreline overlooking it. To bolster their case, they relied on the same data and methods the insurance and disaster-management sectors use.
They found that the nation’s reefs spare about 18,000 people and $1.8 billion in economic assets from floods each year. The results, published in a USGS paper in 2019 and the journal Nature Sustainability in 2021, also showed that states with highly developed coastlines, like Hawai’i and Florida, have hundreds of millions of dollars in property value reliant upon this protection. In places with vulnerable populations living in low-lying areas, like Pacific Island territories, reefs defend thousands of souls. But shave off just one meter, or about 3 feet, of coral reef, the scientists said, and all of them were exposed. Their conclusion: Preserving that yard was a very sensible use of money.
When they presented this to federal agencies, the simplicity of the message, and fastidious spatial detail, left an impression. “What our work says is that if I have a hotel, this reef protected these buildings and those people,” said Storlazzi. “Congress votes on dollars and lives. Us putting it in terms of dollars and lives, at that precision, really resonated.”
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In the aftermath of Maria, this body of research helped Diaz persuade policymakers to act. In 2020, the commonwealth became the first U.S. jurisdiction to declare coral reefs “essential infrastructure.” Diaz spearheaded a FEMA application that argued the islands’ reefs reduced the risk of damage and thus merited repair like any other infrastructure. The resulting award will restore about 5,000 feet of reef around San Juan. Coral losses in these areas have contributed to “continuous coastal flooding and erosion,” according to FEMA.
Since then, Hawai‘i, American Samoa, U.S. Virgin Islands, and, in November, the Mariana Islands have issued similar declarations, and said they will seek federal funds for reef repair. FEMA’s thinking bigger, too. In a statement to Grist, it named three other programs that could fund coral conservation or restoration, all under the Hazard Mitigation Assistance Grants program, which usually spends $2 billion to $4 billion a year. Puerto Rico’s is so far the only funded project, but experts say other applications are in the works.
The Pentagon is paying attention as well. The Defense Advanced Research Projects Agency, or DARPA, has put $68 million toward efforts to invent seawalls that combine corals or oysters with artificial structures. The Defense Department says it has about 1,700 coastal facilities at risk from extreme weather, eroding shorelines, and sea level rise, and that traditional “gray” infrastructure is increasingly inadequate to the task of protecting them.
The emerging science has drawn interest from the insurance industry. The sector paid out $300 billion in the last decade for coastal storm damages, according to insurer AXA. Some in the business think healthy coral reefs can save money. In 2019, reinsurance titan Swiss Re and The Nature Conservancy designed a policy covering a stretch of the Mesoamerican Reef, along Mexico’s Yucatan Peninsula. The policy sold to the local government stipulated that the insurer would pay out when winds within a certain geographic area exceeded 100 knots (115 mph). A 2020 storm blustered past that, triggering an $850,000 disbursal. This allowed first responders to deploy immediately after the storm and graft thousands of shards of coral to the reef, increasing its chances of recovery.
Hench, at Duke, cautions that, as coastal-defense technology goes, reefs are immature compared to conventional measures. Structures made of concrete or rocks have the benefit of being known quantities; an engineer knows how to design them and what to promise a client, like FEMA. Reefs are complex living organisms, and faulty design can cause unintended consequences. “Say we did a huge restoration and four years out there’s a massive bleaching event and many die,” Hench said. “That outcome is different than a traditional engineering mindset. I think we’re still at the very, very early days of how to do that and do it cost-effectively.”
Storlazzi agrees that the next step is gathering performance data on coral reefs to judge them, apples-to-apples, against the same metrics that’d be used for, say, a seawall. He said as data comes out on the current pilot projects, it’ll illuminate a path forward.
The scientists behind all this work don’t seem to think it’s directly threatened by the upcoming change in the White House. President-elect Donald Trump denies that climate change is caused by human activity, and Project 2025, a conservative blueprint for governance, suggests the National Oceanic and Atmospheric Administration should be “broken up and downsized” and FEMA should curb post-disaster activities in favor of states. But Beck notes that extreme weather isn’t going anywhere: Take hurricanes Helene and Milton, which according to early estimates each dealt $50 billion in damage — including to Florida, Trump’s home state.
The group hopes that in this context, the demand for cost-effective solutions to protect people and property will endure across party lines. When Florida Governor Ron DeSantis recently boosted funding for coral-reef restoration, said Storlazzi, the modeling he and his colleagues created was a key driver. “We’re just trying to save dollars and lives, and do it at a lower cost,” he said.
