Pacifica, California, just south of San Francisco, is the kind of beachfront community that longtime residents compare to Heaven. One of its streets is called Paradise Drive; local fishermen brag that Pacifica Pier is among the state’s best places to catch salmon, striped bass, and crab. Every few years, a superbloom blankets the coast with golden wildflowers. When the sun cuts through the region’s famous fog, the sky sometimes glows, as in a Turner painting.
Some of Pacifica’s most dramatic views could be found on Esplanade Drive, where mid-century developers built bungalows on top of a cliff. For almost fifty years, residents gazed out from their back yards to see whales splashing in the Pacific. Then, in 1998, a group of homeowners gathered to say goodbye. “I cannot express how spectacular it has been living here,” one of them, Joe Parker, said at the time. “I’ve seen dolphins out there. I recognize all the seabirds.” Beverly Axelrod, who had spent fourteen years on Esplanade Drive, recalled how her ocean view had “healed everything.” But then a series of vicious storms, fuelled in part by the warm waters of El Niño, had washed away more than thirty feet of the cliff beneath their homes. Workers had to saw Axelrod’s house in half to prevent it from falling into the sea. Ken Lajoie, a local geologist, said that, even after the wind and waves abated, more of the cliff would crumble. The city ultimately condemned seven houses to be bulldozed. One woman was now paying the mortgage on a house that didn’t exist; Axelrod compared the demolition to “being at the bedside of somebody who’s dying.”
In the nineteen-eighties, Pacifica had fortified parts of its shore with a twenty-foot-tall concrete seawall. It had also coated some areas with loose rock, known as riprap. After the storms of 1998, the city shored up its defenses again; state and federal agencies gave Pacifica $1.5 million to pile riprap at the base of the cliff. The city thought of its investments as forward-thinking, in light of climate change. But Lajoie warned that riprap seawalls usually fail. “Stop building structures along eroding coastlines,” he told a San Francisco Chronicle reporter, in 2001. “Prevent future construction of seawalls of any type.”
Lajoie was right: the seawall beneath Esplanade Drive did not stop the sea. In 2010, part of the cliff fell out from under an apartment building, which had to be abandoned and then torn down. By 2018, only one house remained on a portion of the street that overlooked the cliff. After its patio tumbled off the edge, the city government bought the house and demolished it. Around that time, the mayor of Pacifica, John Keener, started talking about adapting to rising seas, and even about “managed retreat.” Instead of trying to fortify the shore forever, he suggested, residents might consider moving out of harm’s way.
Most people, understandably, don’t want to abandon their homes. In a new book, “California Against the Sea: Visions for Our Vanishing Coastline” (Heyday), Rosanna Xia, an environmental reporter at the Los Angeles Times, visits Pacifica and encounters a sign that reads “no managed retreat.” At a city-council meeting, a father of three stands up and declares, “It’s a war with the sea. We may win, we may lose, but we should never give up the ground unnecessarily.” Keener was voted out of office, in large part by residents calling for stronger coastal protections. “The city fell asleep and should’ve seawalled all this decades earlier,” one man told Xia.
Pacifica embodies one of the central disagreements about rising seas. Fight or flight? Stay or go? Flight can seem unimaginable. But, if we try to fight the ocean with rock and concrete, it will cost us—and it may not work. Pacifica currently plans to borrow tens of millions of dollars to reinforce its seawall. Writing for a community blog, Gregg Dieguez, a critic of this plan, objected not just to its price but to the “moral hazard” it would create: by forestalling erosion, the seawall might only encourage more people to live in risky places. “Once sea level rise gets here, it’s never going away, at least not for thousands of years,” Dieguez wrote. Meanwhile, he noted, only one per cent of the homes in Pacifica were at risk. “You will have to decide, as a group, whether paying to hold back the tides is a good use of your precious money,” he concluded. It’s a question many more of us will soon be asking. When do seawalls make sense? And when is it better to give in to the tides?
The oldest known seawall was built around 5000 B.C., after a period of warming that melted glaciers and lifted the Mediterranean by a staggering twenty-six feet. A Stone Age community, living near a beach in present-day Israel, tried to ward off the sea with a wall of three-foot-tall boulders about the length of a football field. But, in the millennia that followed, the Mediterranean rose even more. Archeologists ultimately discovered the stones on the seafloor, under ten feet of water. The site, they wrote, was “ominously relevant” to our time. Other excavations have turned up ancient coastal fortifications in places like Lebanon and Egypt. Ancient Roman ports used a kind of concrete that grew stronger in contact with water.
In the war with the sea, the Dutch have probably spent the longest in the trenches. When Pliny the Elder visited the Low Countries in 47 A.D., he compared the people he met to marooned sailors living on artificial mounds of mud; by the early Middle Ages, locals started to build a seawall. A 1948 book by a Dutch engineer, “Dredge, Drain, Reclaim: The Art of a Nation,” describes the wall as a major victory in an existential struggle. “Formerly the terrible evils of the sea, the storm floods and the more terrible marine erosion, had to be endured, but now the fight began to throw the sea out of the country; a fight not yet ended and a fight for to be or not to be,” he wrote. But the walls had a side effect. They locked the land into place, trading in a dynamic shoreline for one that could not adapt as easily, and that would need to be defended forever.
There are many kinds of coastal protection. Some of the most effective are entirely natural. Marshes, mangroves, and even sandy beaches can absorb the destructive power of waves, helping to soak up water and energy that would otherwise wreak havoc. Engineers can fortify a shoreline by replenishing lost sand, or by adding rock, wood, or concrete. It’s also possible to augment the shore. A rock pile that parallels the coast, shielding the beach from waves, is called a breakwater. A pile that juts out to sea, trapping sand on one side, is called a groin. All of these measures are already widely used on coastlines around the world.
Hard seawalls may be the bluntest instrument in coastal engineering. Typically, they are made from concrete, stone, wood, or metal, and rise vertically from the shore. But a wave that strikes a seawall never breaks and dissipates, as it would on a beach; instead, it bounces off like an echo, its destructive force intact. In the end, the flow of water and sediment is a zero-sum game. For a wave to spare one place, it has to strike another; for sand to accumulate somewhere, it has to wash away from somewhere else.
According to the sociologist Summer Gray, seawalls are less a practical solution than a product of technocratic ideology—one that colonial powers have exported around the world. For all their potential benefits, seawalls “harm the environment, shift vulnerability downstream, lead to the disappearance of the beach, and create cycles of dependency,” she writes in her new book, “In the Shadow of the Seawall” (University of California Press). In one meticulous chapter, Gray recounts how the Dutch West India Company settled the low-lying coast of Guyana, in South America. Planters enslaved Africans, who were forced to build seawalls and then to cultivate sugarcane. The people of Guyana eventually came to see their aging seawalls as a necessity; there was now significant development on low-lying land. When storms surge over our protections, we tend to wonder why they weren’t higher, rather than questioning the logic of living by the sea.
In the nineteenth century, Gray writes, engineers started to consider the unintended consequences of fortifications. In 1899, Edward Case, the keeper of the Dymchurch wall, which protects Romney Marsh, in southern England, noted that, when the “Lords of the Marsh” built their manors in the muck, they locked themselves into centuries of dependence on the wall. “But for the value of the land at stake . . . the struggle must have been abandoned,” Case observed. After waves washed away sediment in front of the wall, he made a counterintuitive argument: seawalls can contribute to the erosion they are supposed to prevent. At the base of a seawall, the constant churn of water stirs up sediment; that sediment is then swept back to sea. This phenomenon is now known as scour. Sometimes the water erodes so much sand that it causes walls to collapse.
“Over the Seawall: Tsunamis, Cyclones, Drought, and the Delusion of Controlling Nature” (Island Press), by the journalist Stephen Robert Miller, tells a story of double-edged engineering in Bangladesh, where the flow of water and sediment creates a rich and ever-changing agricultural zone. The region “is not so much a world pestered by water as one defined by it,” Miller writes. But, when the British colonized Bangladesh, they fractured the waterscape with embankments, farms, and railroads; after they departed, international development workers went a step further, walling off a hundred and three low-lying islands that they called polders, using a Dutch word for land that is reclaimed and then fortified. Although these walls protect lives and property, they also draw Bangladeshis to areas that are vulnerable to storm surges, which devastate coastal communities during tropical cyclones. Miller writes of some floods that, paradoxically, killed more people in the places with stronger walls. “The embankments provide only pseudo security,” Dilip Datta, an environmental scientist at Khulna University, tells him. “They work against our best interest.”
When I ran these critiques of coastal protection by Rachel Gittman, a marine ecologist at East Carolina University, she offered another reason to worry about seawalls. Natural habitats already serve as powerful buffers against flooding, she said. They absorb water and energy; this is why marsh and mangrove restoration is often the best way to protect a coast. By contrast, when coastal communities wall off the shoreline, they tend to trap ecosystems between the water and the wall, causing a process called coastal squeeze. “It can be a slow drowning of those habitats,” she told me. When they disappear, we may be more vulnerable than when we started.
Our present dilemma is worse than it needed to be. In 1981, a group of coastal geologists gathered on Skidaway Island, in Georgia, to write a report called “Saving the American Beach.” They warned that rising seas and migration toward the ocean would expose a growing number of people to erosion, flooding, and storms. Saving the shore, they argued, might “involve drastic and unpopular measures such as assuming that buildings adjacent to the beach are temporary or expendable.” By the time a second group of experts met at Skidaway, in 1985, their fears had escalated. “Sea level is rising and the American shoreline is retreating,” they wrote. “We face economic and environmental realities that leave us two choices: (1) plan for a strategic retreat now, or (2) undertake a vastly expensive program of armoring the coastline and, as required, retreating through a series of unpredictable disasters.”
The Skidaway experts were hardly the only ones to foresee our current circumstances. Yet, in the decades since their reports, the number of Americans who live near a coast has almost doubled. In 2018, coastal counties were home to a hundred and twenty-eight million people, or forty per cent of U.S. residents. Today, about fourteen per cent of the coast is fortified with hard barriers.
Coastal protection is usually treated as a cost-and-benefit problem. The more people and property in a given place, the greater a seawall’s benefits. Last year, when the Army Corps of Engineers proposed a vast network of seawalls and gates to shield New York and New Jersey Harbor, it argued that the fifty-three-billion-dollar project was a very good deal: although it “will not totally eliminate flood risks” in the area, it would cost much less than repairing the city after every storm. (Hurricane Sandy caused an estimated nineteen billion dollars in damage in New York City alone.) The densest, wealthiest, and most vulnerable coastal cities—Bangkok, Shanghai, Rio de Janeiro, San Francisco, Miami—are likely to make similar calculations. Yes, a seawall may erode the shore and draw even more people toward the water, but lives and livelihoods are already concentrated there; if a seawall could save them, don’t we have to build one? The opposite, presumably, will be true in rural and ecologically fragile places; a seawall might endanger too many species, or wash away too many beaches, or simply protect too little, to justify the costs.
Such calculations, however, leave a lot out. Industrialized societies have never been good at valuing the nonhuman (the coastal ecosystems that seawalls squeeze out) or the intangible (the cultural, historical, or spiritual value of a place). The cost-benefit equation doesn’t account for moral hazard, either. Seawalls are supposed to shield us from risk, but, if they draw people and property to the shore, they might wind up exposing more of us to it. Money also tends to protect money. Do we want to live in a world where only the wealthy can afford seawalls, and everyone else must retreat or risk drowning?
Gray, the sociologist, is wary of managed retreat, too. “Staying in place on a warming planet is an inherently unequal struggle,” she writes. She notes that those least able to fight the pressure to relocate—for example, residents of the Maldives, where she sets half of her book—may be urged to move. “Resilience planners often ask vulnerable populations to transform themselves in drastic ways that are not asked of ‘nonvulnerable’ populations,” she writes. Coastal communities that can’t afford seawalls could be left with no good options. Gray never fully unties this knot; she ultimately dedicates her book to “the frontline communities who stay and fight.”
If our math is wrong, what could right it? In an era of rising seas, we are primed to think of coastal protections as prudent. Given their unintended consequences, however, we should be wary of their risks and skeptical of their benefits. Instead of building as many walls as we can, we should build as few as we need to—and only when they protect what matters most. This last notion, of what matters most, is a question, not an answer. Seawalls are expensive, and unfairness will be one of their heaviest costs.
In “California Against the Sea,” Xia, the environmental reporter, writes about the difficult realities of trying to incorporate fairness into our tally of costs and benefits. In the Southern California city of Laguna Beach, Xia examines a picturesque public shoreline that separates mansions from the sea. Here, in 2015, a wealthy couple bought an aging waterfront home; they remodelled it into a stone-and-glass fortress and shored up a private seawall at its base. In a sense, they were weighing the costs and benefits of climate adaptation—but only for themselves. A neighbor soon complained to the California Coastal Commission that the wall was a threat to the beach. It was now up to the commission to decide if the wall was allowed.
Xia tracks down Orrin Pilkey, a co-author of the Skidaway reports who has become known for his single-minded insistence on managed retreat, to ask him for his opinion. He argues that the neighbor was right to worry. A private seawall can deflect waves toward neighboring houses, forcing them to erect walls of their own—a domino effect in reverse. “If one homeowner wins, the whole state loses,” Pilkey tells her. “If you give up the fight on one location, then you’re going to have to give up eventually on all locations.”
The commission seemed to agree: it declared the wall illegal, ordered it torn down, and fined the couple a million dollars for remodelling a coastal house without its permission. It also resolved to oppose new seawalls up and down the coast, with few exceptions. “Seawalls damage beaches by preventing sand from reaching the beach, which eventually causes beaches to shrink until they disappear,” the commission said in a release. “In an era of sea level rise, the long-term effect of sea walls is to temporarily protect the property behind them, at the permanent expense of public sandy beach space.”
In theory, a moratorium on residential seawalls is itself a kind of coastal squeeze, meant to encourage relocation. This is a complicated position to take, but it reflects a complicated reality. The Coastal Commission seemed to be saying that coastal Californians were free to stay until the sea came for their homes—as long as they did not try to stop it from doing so. If you can’t retreat behind a wall, you might retreat to a landlocked town that doesn’t need one. In practice, however, many homeowners would rather dig in for a fight. The Laguna Beach family took the commission to court, and, when Xia finished her book, the rogue seawall was still standing.
On a windy evening in August, I biked to a park in lower Manhattan to meet Yuki Miura, a soft-spoken researcher who has modelled the flooding that a hurricane would inflict on Manhattan. Miura, who grew up in Tokyo, told me that a mega-storm will come eventually. In fact, “it already happened,” she said. The storm surge from Hurricane Sandy, in 2012, peaked at nearly fourteen feet, inundating hundreds of city blocks. “Whenever I run the model, there are certain areas that pretty much always get flooded,” Miura told me. We were standing in one of them.
We walked together toward the East River until we came to a hulking concrete wall, which had been built so recently that it was still wrapped in plastic. Miura told me that, when she visited this area a couple of years ago, as a doctoral student in civil engineering at Columbia University, the lower-Manhattan seawall, known as the big U, was only a proposal. “It didn’t exist at all,” she said. She was happy that, at least in this one place, the city had started to fortify the shore.
To gain access to the waterfront, we walked through a truck-size gap in the wall, passing a wheeled floodgate that looked like a narrow train car. Then we forded a stream of after-work joggers and came to a little cliff of concrete by the river. On the other side of a metal railing, the wake from passing ferries lapped at New York’s fortified shoreline.
When the next storm comes, Miura told me, the river will start to climb—slowly, more like a rising tide than a tsunami. If a strong hurricane strikes when the tide is already high, “this area would be underwater,” she said. The seawall behind us, which rose sixteen feet above sea level, was tall enough to limit—though not eliminate—coastal flooding from the biggest possible hurricanes. But Miura warned that, if a storm strikes while the wall is under construction, before it protects the entirety of lower Manhattan, then water will find the unprotected areas, flow behind the wall, and fester there. So far, only a small portion of the big U has been built.
I asked Miura whether, instead of building walls that could anchor people along the coast, New Yorkers should think about moving away from the shore. “Managed retreat might be a good option in different regions,” she told me. “It’s very hard to imagine here.” Manhattan is home to 1.6 million people and trillions of dollars of coastal infrastructure. Once you’ve built skyscrapers and hospitals and highways along the water, just a few feet above sea level, it’s hard to imagine any path into the future that leaves so much of value behind.
Talking to Miura, I thought about all of the choices that had led to this moment. We are fortifying the shore in part because we burned fossil fuels; we burned fossil fuels because we believed that some other place, or some later generation, would bear the consequences. In this sense, the story of seawalls and their downsides mirrors the larger story of the climate crisis. “We need to solve the problem from the bottom,” Miura told me. Until we do the hard, collective work of slashing emissions, the planet will keep getting hotter, the water will keep rising, and the storms will keep getting worse.
As the sun set, Miura and I looked out across the water. The clouds were turning purple and orange; a few boats drifted by. It was easy to understand why someone would want to live here. Then my eyes came to rest on the apartment blocks and factories that dotted the Queens waterfront—an area that is as densely populated as parts of Manhattan, but where no comparable seawalls have been built. I asked Miura what would happen there. Could the water that would have flooded Manhattan instead end up somewhere else, like Queens?
“It will be shifted, yeah,” Miura told me. “Water has to go somewhere.”