In the small, coastal city of Saco, Maine, not too far from where my brother lives, the Army Corps of Engineers is currently busy building a wall of rock to keep out an invader: the sea. Actually, what they are building is what’s called a spur jetty—that is, a wall jutting out from an existing breakwater that, due to rising seas and more intense storms, is no longer up to its task. At the cost of $45 million, the Saco wall will be constructed by piling massive rocks atop one another some 20 feet above the usual level of the sea. But what’s usual, these days, anyway?

The Saco coastline is, quite literally, disappearing into the sea. As a result of just two January 2024 storms, the coast of Saco, along with neighboring Kennebunkport and Biddeford, lost 28 percent of its shoreline—most of which was never recovered or rebuilt. So intense were these storms that the water lifted higher than it had ever been recorded, sweeping houses, boats, cars, bridges, pieces of lighthouse, and critical ecosystems away with it. Two hours north, where my mom lives, the water lifted a neighbor’s boathouse off its foundation and deposited it a quarter mile down the coast, on someone else’s lawn. Mainers lost treasured homes, businesses, piers, and economies. Hence, the wall.

It’s a favored human response to encroachment, real or perceived. In the U.S., the call to “build the wall” immediately brings to mind the southern border. How common it now is to gesture to the barricade, stoking fears and convincing the population that it's under attack from the outside. Of course we’ve long used walls to lock people inside, too: behind the iron curtain, for instance, or on the infected side of the Vaucluse mountains in France during the time of the plague.

But the sea is a particularly beguiling invader, for anyone who chooses to see it as such. In recent decades, just as we’ve built more border walls than ever recorded, humans have been building more seawalls, too. As climate catastrophe puts coastal communities, ecosystems, and economies in grave danger, walls have been erected in places ranging from the sinking Pacific Islands to Cuba, Greece, and California. One climate report estimates that, between 2019 and 2040, U.S. coastal communities will have paid over $400 billion in seawall construction alone.

The thing with walls is they don’t totally work—not comprehensively, anyway, and not forever. People can go over, under, around, or through walls, and so, too, can the ever-rising sea. In the immediate term, there’s no doubt that places like Saco need more and fortified walls, quickly, to serve as wave breaks and to protect against storm surges. But, as is always the case with such interventions, they only do so much for so long: They have to be maintained and expanded, and, as the sea levels rise ever higher and storms become ever more unpredictable, they’ll need to be built and rebuilt, ever higher and stronger in turn. In this way, the rigid nature of a wall as a temporary stopgap feels like a perfect metaphor for our response to the climate crisis writ large.

Every place on earth has its particular climate vulnerabilities—devastations wrought, anticipated, or well underway. Maine’s weakness is, without a doubt, sea level rise. In the last 100 or so years, Maine's sea level has risen roughly eight inches owing to factors like glacial melt and warming seas, and the speed at which it is raising is quickening, too. By 2050, the state reports expecting an additional 1.5 feet of rise, and four feet by 2100. But the state’s coast has something going for it, too: a huge (if imperilled and greatly diminished) swath of wetlands, totalling roughly 25 percent of the state’s land mass. That’s four times the acreage of wetlands from the rest of the New England states combined.

Wetlands are perhaps the opposite of walls in spirit; they are languorous, pliant ecosystems where land and water are perpetually yielding one another new ground. They are a porous space between. But when it comes to sea level rise and storm surges, they serve a similar purpose as walls. The long sea grasses of tidal wetlands help slow a storm wave and trap incoming sediments, while the ground absorbs the sudden influx of water with spongelike ease—making a receptive space that provides durability. This is to say that the communities surrounded by intact tidal wetlands unsurprisingly fare far better during massive storms than those solely protected by a wall.

In the past decade or so, the utility of these wetlands has become much clearer to lawmakers, and to funders, too. Last year alone, the Nature Conservancy awarded $4.6 million to coastal communities throughout Maine to restore and protect their wetlands as an act of climate resilience. It’s not all that easy to build a marsh, but you can restore one—and the move to soften rather than harden the shoreline demonstrates efforts to return to a pre-anthropocene logic before it’s too late. The marsh as buffer, the marsh as metaphor, the marsh as invitation: into porousness, proneness, that tidal susceptibility that is also durability. Isn’t it so often the case that human technologies are far inferior to the ones Earth already supplies?

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The 2024 storms really were bad in Maine. Towering waves pummeled the Pemaquid Point Lighthouse in Bristol, destroying the Bell House and flipping a 775-ton rock along the shore. The surges bent and leveled piers in Harpswell and in Old Orchard Beach, where parked cars began to float and people had to trudge waist-deep through water in town centres, while walls of houses were sheared off like dainty cuts of cheese.

The marshes did their good work. The problem is that in Maine, as with coastal regions all over the world, we’ve built our cities and towns atop these critical wetlands, thus destroying or curtailing them. We need to bring them back, yes, but we also need to allow for the remaining coastal wetlands to move and shift—to retreat, essentially, as sea levels rise, so that they, too, don’t get drowned out.

Not far from where the Saco seawall is being built, a quarter-mile stretch of road connects Cape Elizabeth, where my brother lives, with the town of Scarborough, winding through the Spurwink Marsh. It’s a pretty, little-used road that’s prone to flooding during the year’s highest tides. During the harsh January 2024 storms, the road was completely submerged. A car washed away, and, had they not been promptly rescued, its passenger might not have made it out alive. The road, bifurcating the marsh landscape, was being overlaid by that landscape’s natural retreat. As the sea levels rise, a healthy marsh begins to move inland. But a road like this leaves it nowhere to go.

As one town planner told the Portland Press Herald: “The road faces so many challenges—a failing culvert, an impaired marsh, king-tide flooding—yet it only has 1,200 daily trips. After a while, I had to ask myself: ‘Are we sure we even want to fix it? Is this where we want to spend our limited resources?’”

What was more important, in other words, the marsh or the road?

The answer—its own gesture of softness and human pliability—was the marsh. The towns are getting rid of the man-made road. Now, the wetlands will have more space to move as the sea continues to rise. This decision is not, of course, entirely altruistic, for the salt marsh’s viability is critical if Scarborough and Cape Elizabeth are to withstand the coming seas and storms. It’s a decision, instead, that acknowledges the complex entanglement of human civilization, full of beauty and folly alike, with the so-called “natural world.”

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This summer, while on a reporting trip to Greece with my husband and four-year-old, we found ourselves bumping down a small road on the island of Ikaria in search of a place to swim. Fires were raging throughout Greece due to unusually high temperatures and winds but, blessedly, where we were wasn’t on fire, just hot. We rounded a bend to find a charming little fishing harbor where a rock wall completed a horseshoe bay and stilled the water into something like a swimming pool. Several ramps and ladders lowered directly into the sea and there were probably 60 people out bobbing happily in the cool deep, the water so clear and placid you could see the sifting sand 20 feet below.

Among the bathers were elders, flirting teenagers, thrashing kids, young families like us, and it was evident that this was a daily ritual for many: to come down to the harbor once the fishing boats were all lashed to their cleats and dip in. It was the wall that made all this possible—the fishing, the swimming, the cavorting with neighbors. But a wall like this only functions as a truce. It’s meant to slow the windblown sea and ease the break—not stop it entirely. Anyone who has spent meaningful time with the ocean knows that it’s not a stoppable force. We have to let it ease and lift and move; and regardless of our frantic efforts to the contrary, it simply will, anyway.

There is no natural world, of course—only the world as it is. To mutually implicate human and nonhuman existence is to function like a marsh does, a place that is both water and land, sea and soil, fresh and salt, fish and bird: We are this, we are that, and we are all of it. We have to move this way, together, in truce, in order to survive. ♦