A gnarled old pine marks the entrance to the Sprague River Marsh. It is high summer, a short season of riotous green in Maine. But the tree hasn’t taken any cues from the tilting of the planet, the long hours of sunlight, or the sudden warm spike. Its branches extend, empty and bare. This pine must be at least a hundred years old, but as with so many others I saw lining the banks of tidal marshes up and down the coast, too much salt water had too regularly soaked into the ground around the tree’s root system, killing it. On the surface, a single tree might seem inconsequential. But its death is a sign of a much larger transformation—the disintegration of tidal marshes all along the coast.

Because tidal marshes sit exactly at sea level, they are one of the first landscapes to show the effects of accelerated sea-level rise. Sometime during the past half-century or so, this tree’s taproot started to occasionally suck down salt water instead of fresh. It was stunned and stunted at first. Then it stopped growing. The sea kept kneading into the aquifer, storms got stronger and dumped more standing water onto the marsh, and it and so many other elegant old trees all along the coast—from the Sacramento-San Joaquin River Delta to the Gulf of Mexico—started to die.

Twenty-five years ago, hardwoods and pines often thrived alongside our marshy shore. Now not. It is still hard for me to believe that a departure this big began in my lifetime. I’ve encountered so many of these bare and lifeless forms that I have come to think of them as a series of memorials, a supersized Christo installation that spans the entire country from the Louisiana bayou all the way up here to this remote corner of the Gulf of Maine. Together they commemorate the tipping point: the moment the salt water began to move in. And now that sea levels are rising more quickly than they have in the past twenty-eight centuries, an even bigger change is happening: the ground itself has begun to rot.

I walk through a patch of poison ivy and over a weathered outcrop of granite into the marsh. The moment I step onto the upper portion of the Sprague, I know that it is in trouble. There I am met by the musky, almost strawberry scent of decomposition. Most marshes smell a little bit, but here the scent is overwhelming. A healthy marsh is firm underfoot. Here the earth quakes like Jell-O. With every step, bubbles burble from the accrued depths, releasing what captive sulfur lies beneath.

For the researchers I visit at Sprague, the smell of the rotten marsh is halfway normal. For me it conjures up images of my neglected compost bin.

In my mind, rot is something vegetables do. A still life will rot, which is why some artists prefer to paint plastic fruit. Limbs rot when gangrenous. I do not think, until this moment, that it is possible for the ground itself to rot. Or that when it does, it might just help heat up this precious pebble even faster.

*

“Welcome to our rotten marsh,” says Beverly Johnson, a professor of geology at Bates, a small liberal arts college about thirty miles inland where I, too, teach.

Beverly speaks a kind of hybrid language—half scientific fact, half block-party-accessible. Her wardrobe is a similar mix of business and pleasure. She wears knee-high wading boots, long black shorts, and a maroon T-shirt with a hiker and mountain peak airbrushed across the front. She carries in her periwinkle Osprey pack a change of socks, three water bottles, and a yellow hardcover all-weather geological field notebook, the words “Gulf of Maine” scribbled down the spine in black Sharpie.

Dana Cohen-Kaplan and Cailene Gunn, two of Beverly’s students who have been studying the relationship between marsh degradation and the release of greenhouse gases for their senior thesis projects, accompany Beverly in the marsh. Since 1977, Bates students and faculty have been conducting research in and around the Sprague. But forty years ago the concerns of the day were notably different. One of the earliest theses written about the Bates-Morse Mountain Conservation Area (of which the Sprague is but one part) investigates porcupines and their food preferences. Today, most who make the journey to the coast study how and why the area is changing as a result of human activity. In our era of unprecedented geologic transformation, the very act of scientific observation has taken on an added sense of urgency. “It’s a terrifying and wonderful time to do this kind of work,” a conservation biologist had told me while walking through a tidal marsh a hundred miles south of here. “Possibly, in my lifetime, all I have worked to defend will be underwater. We will want to know why, but we need the data first.” The chance won’t come again.

In recent years, scientists have discovered that coastal wetlands (salt marshes, mangroves, and sawgrass meadows) store a quarter of all the carbon to be found in the earth’s soil, despite covering only about five percent of the earth’s land surface. That means that an acre of healthy coastal wetlands will clean far more air than an acre of the Amazon. “They sequester about fifteen times more carbon than upland forests,” Beverly tells me. “But how effective are these ecosystems when they have been dammed, diked, culverted, or drained? That’s what we’d like to know.”

Over by the dead tree Dana unloads a large Plexiglas box and an eighty-thousand-dollar machine that looks like a waterproof stereo receiver. “It’s a cavity ring-down mass spectrometer,” says Joanna Carey, a biogeochemist, who, like the machine, is on loan from the Marine Biological Laboratory at Woods Hole, Massachusetts. “We use it to measure carbon dioxide, methane, and water vapor levels being ‘respired’ by the marsh so we can get a better idea of how higher sea levels will alter the net balance of greenhouse gases in these already altered coastal ecosystems.” As the marsh is further destabilized, it is possible that the carbon that was stored in the root systems will break down, releasing the very gases the marshes were once so good at pulling out of the air back into it.

Dana places the contraption into a wheelbarrow. “Cailene and I nicknamed it the ‘Science Box,’” he says, closing the gate on the college van. It used to be that we thought the earth’s climate and its underlying geology changed slowly and steadily over time, like the tortoise who beat the hare. But now we know the opposite is mostly true. The earth’s geophysical makeup doesn’t tend to evolve incrementally; it jerks back and forth between different equilibriums. Ice age, then greenhouse earth. Glaciers covering the island of Manhattan in nearly mile-thick ice, then, in that same spot, a city of eight and a half million people. The transition between the two is often quick and relatively dramatic. Contraptions like the Science Box help us keep track of just how radically things are changing, illuminating the ways in which human activity is pushing the planet beyond greenhouse earth into some even warmer, preternatural state.

The Science Box takes various vapor emission readings at a rate of one per second. From these readings Dana will generate one “flux,” or image, of the overall rise or fall in methane and carbon dioxide coming off of one square meter of marsh. Then he will compare the fluxes gathered in healthy areas against those recorded in areas that have already begun to rot from within, creating an image of the potential impact of sea-level rise on a tidal marsh’s ability to sequester greenhouse gases.

The amount of data the Science Box generates in four minutes would take a human 3,600 minutes to collect by hand—which is exactly what Cailene spent her summer doing. That’s because Cailene is studying Long Marsh, a “fingerling” marsh about ten miles northwest of here as the crow flies. There is no road to Long Marsh’s terminus: to reach the transition zones where the readings are most telling, Cailene must drop down the side of a culvert near Long Marsh’s mouth. Then she hikes through the waist-high marsh grasses, hopscotching across rivulets and drainage ditches until she reaches the end. It takes her thirty-three minutes to travel from stem to stern. She can’t safely cart the Science Box all the way back there, which is why Cailene has been collecting her readings the old-fashioned way—by hand, with a 25 mL syringe and Exetainer. Cailene explains, tapping away at the calculator app on her cellphone, that it took her all summer to produce one-tenth of the data the team would collect that day.

As I drove down Route 209 and out the fog-struck peninsula that morning, the local NPR radio personality likened the weather to pea soup. The midday heat was bound to break records, he warned. Now, listening to Cailene, I understand that it was not only going to be the hottest day of the summer but also one of most important for the young researchers. In front of me, Dana pauses, adjusting his hard-brimmed straw cowboy hat. He drops his hands to his sides and tugs at his sun-bleached Cisco Brewers T-shirt, pulling it over his belt. Then he looks out across a sea of saltwater cordgrass and black needle rush, places his hands back on the wheelbarrow handles, and enters the humming midmorning light. Not only will today’s work comprise the raw material of his yearlong senior thesis, it will hopefully begin to illuminate how drowning tidal marsh ecosystems could inadvertently contribute to the ongoing inundation of the coast.

*

Cailene and Dana devoted their summers to better understanding what separates a healthy tidal marsh from one that is not, and the rate at which both release greenhouse gases into the atmosphere. Or, as Beverly describes it, “They are filling in the equation that describes today’s carbon cycle.”

Global sea levels have risen about eight inches since we started keeping track, in 1880. If they kept on rising at this rate, by century’s end they would be roughly five inches higher than they are today. Scientists expect to see anywhere between an additional twenty-four to eighty-four inches of sea-level rise by 2100, and every year it seems the estimates creep even higher still. The upper reaches of the Sprague River Marsh are covered in a thin film of white bacteria, a sign that sulfide is bubbling up from below where decomposition is taking place. All around the world, as the rate of sea-level rise accelerates, tidal marshes are becoming inundated and, like here, they are starting to rot. Some places, like the southern edge of Louisiana, have already passed through this transitional process, while others, like vast swaths of the Everglades, are only recently beginning to show signs of collapse. As these marshes become flush with salt water, they are contributing to atmospheric warming. But just how much and at what rate remains unclear. That’s partly because each location is unique, with different kinds of flora respiring at different rates, and also more generally because, throughout Western history, tidal wetlands were thought to be the home of swamp serpents and marsh monsters—the boggy, slimy source of malaria, disease, and death. As such, they have long gone overlooked, which is why the research taking place out here in the Gulf of Maine is so important.

The US Fish and Wildlife Service likely didn’t understand the connection between marsh-rot and climate when they decided to “plug” a ditch that had likely been dug through the Sprague River Marsh in the 1930s by the Civilian Conservation Corps. The Sprague is not unique in this way. By the end of the decade following the Depression, roughly 90 percent of New England’s saltwater marshes were grid-ditched. “Ditching,” which initially augmented the production of salt marsh hay back in the 1700s, was, by the beginning of twentieth century, the go-to method for reducing mosquito populations in coastal communities. All along the Eastern Seaboard, CCC-funded workers took shovels to the low-lying coast’s swampy land, weaving a crosshatch of manmade incursions across the marsh, hoping to drain the remaining sections prone to retaining water.

The Civilian Corps of the ’30s didn’t care that ditching a tidal marsh wouldn’t just cut down mosquito populations, but would transform the hydrology of the entire ecosystem. The standing water in which mosquito larvae hatched was greatly reduced, and with it went hundreds of other species.

Dragonflies and water beetles.

Mummichogs and silversides.

The seaside sparrow.

The great egret and white ibis.

Which is why the US Fish and Wildlife Service started plugging ditches up and down the coast over a decade ago. By intervening in an already altered hydrological system, they thought they might be able to return the marsh to a state of equilibrium. They thought they might be able to bring back the water beetles and wading birds. But, as it would turn out, layering one kind of human intervention on top of another only dragged the Sprague further from its starting point.

Not much more than a four-by-eight-foot piece of plywood, the idea behind a ditch plug is simple enough: stop the tidal flow through the manmade channels. The goal is to reintroduce an element of standing water into the marsh. But ditch plugs are too effective at restricting flow. Freshwater from the upland side filters into the marsh, impounding the salt marsh hay. And whenever an exceptional high tide or storm surge reaches the upper marsh, the barrier is breached and salt water gets stuck in place behind it. As a result, everything above the plug is permanently inundated with saline-rich water, and as the water starts to evaporate, the saline concentrations shoot even higher. The rhizomes in the marsh grasses that are not used to these conditions begin to decompose, the ground around them collapses, and the greenhouse gases long stored in the sediment are released into the air. At least, that is what we suspect is happening.

“The US Fish and Wildlife Service really screwed this up,” says Beverly, straddling the channel bloated with brackish water behind the plug. “Though they know this now.” Already the plywood has begun to decompose. Its edges are egg-yolk yellow and dusty green, the center buckled. Fifteen years ago, the ditch plug seemed like a reasonable enough solution to what was then the most pressing issue of the time—restoring a pre-industrial tidal marsh pool habitat. But what was once considered a blessing for wading birds and water beetles is today, thanks to stronger storms and higher tides, causing the marsh to rot.

Later, when I type “what rots” into Google, Google tries to finish my sentence by suggesting: What rots teeth? What rots first when you die? What rots quickly? I discover that acid rots teeth. Cell membranes in the liver are usually the first thing in the human body to rot. Potatoes rot quickly, and I don’t need Google to tell me that they smell bad when they do.

Google does not suggest finishing my sentence with: What rots marshes? It is not the first time the search engine and its millions of users—whose habits dictate the autocomplete option—have been, in my humble opinion, misguided. Because if marshes are among the largest carbon sinks in the world, and if rot transforms them from huge carbon sinks into huge carbon sources, then we surely do want to know what rots marshes and, perhaps more importantly, if there is anything we can do to better prepare them for the future that is already here.

When I look out across the white slime that coats the once-loamy ground above the ditch plug, I know that little piece of plywood is, in a very basic sense, mimicking what will happen to the world’s marshes as the height of our oceans continues to climb. My fever dreams of tidal wetlands—and all the species endemic to them—drowning, of our coastlines contracting, and of mass migrations inland return with prehensile force. They drag me deeper into the marsh, out among the rotting cordgrass where the ground quakes like chocolate pudding. There, at the decomposing center of the Sprague, I stand, dumbstruck, really, by our planet’s transformations.

I am starting to be able to see not just the dead trees sprinkled along the shore like so much confetti, or the fistful of decaying grass I hold in my hand. I am beginning to make out the rough outline of our future coastline. Everywhere that once was a tidal marsh will likely be underwater. The words of Ben Strauss, the executive director of Climate Central, echo in my mind: “It’s not a question of if, but when.”

*

Think of a tidal marsh as a transitional region where distinctions blur and the entirely wet world morphs into the almost entirely dry one. It is a liminal ribbon. An in-between. A spit of land at the edge of things where the laws governing the place change four times a day, with the tides. Tidal marshes are frontiers, and as Gary Snyder says, “A frontier is a burning edge, a frazzle, a strange market zone between two utterly different worlds.” The balance these unique ecosystems strike between the ocean and the land is delicate and difficult to defend. Historically, when sea levels drop a few centimeters, the marsh drops down too, and when they climb, the marsh goes with them. “But as rates of sea-level rise continue to accelerate, it’s expected that they will outpace Maine’s marshes’ ability to adapt,” Cailene tells me. Land that once was built up through the accumulation of sediment over time is already slipping beneath the rapidly rising sea’s surface. And if the marsh abuts a piece of infrastructure, like a road—as is the case with the Sprague—or stone—as is the case with Long Marsh—the ecosystem is squeezed between the sea and the hard stop along its upland edge. Like the pine tree I walked past earlier in the morning, it will drown in place.

A recent study released by the National Academy of Sciences predicts that as coastal wetlands continue to be transformed by atmospheric warming they will release more methane into the air. But what makes a wetland vulnerable may be more complicated than simply measuring its height and location on a map. As Kimbra Cutlip wrote in a recent issue of Smithsonian Magazine, “How much carbon wetlands take up, how much they release, how quickly soil accumulates or subsides are all factors that are intertwined with one another and dependent upon a variety of influences. Imagine that you pull on one line in a tangled web of ropes. As one loop loosens, another tightens, changing the shape of the whole bundle.” When humans interfere with marsh hydrology—by ditching, plugging, draining, diking, culverting, and developing alongside and in these unique landscapes—they are yanking, even severing, the ropes that tie the marsh together.

“We know that healthy marshes have historically kept pace with moderate changes in sea levels, but how they respond to those kinds of changes when ditched, plugged, and tidally restricted is another thing,” says Cailene. The two tiny silver geckos tacked to her ears reflect the sun. “And that’s important because, for example, of the 131 marshes here in Casco Bay, 128 have been altered.”

“There are twelve ditch plugs littered throughout the Sprague,” Beverly chimes in, “and hundreds throughout marshes up and down the coast.”

In the short term, widening culverts, removing man-made infrastructure—things like ditch plugs and roadways—and reconnecting marshes to the rivers that have long provided the silt needed for sediment accretion would likely increase these important ecosystems’ ability to keep pace with sea-level rise. However, as the rate of the rise itself accelerates, what tidal marshes will need more than anything else is space, room to migrate up and in. And, though few want to admit it, providing space likely means relocating some of the human communities we have built along the seashore.

Just below the buckled piece of plywood, Dana drops a Plexiglas chamber over a preselected square of healthy marsh vegetation. Joanna Carey, who has spent much of the past year using her ring-down mass spectrometer to calculate net fluxes of the major greenhouse gases in both high and low marsh environments all around New England, lays the Science Box on two milk crates. She plugs the machine into a set of tubes that run over to the chamber. Then she presses a button and the Science Box begins to whir, almost immediately producing data. Everyone crowds in to look at the stream of numbers scrolling up the screen.

“Right now we aren’t seeing any methane emissions, which is what we want,” says Beverly. A molecule of methane, one of the most potent greenhouse gases on the planet, can, in the short term, heat the atmosphere eighty-six times as much as a molecule of carbon dioxide. “And the carbon dioxide is dropping too, because the plants are photosynthesizing,” she adds. In essence, they have verified what they already know—healthy marshes are good at sequestering and storing greenhouse gases. The data gathered here, below the ditch plug, will serve as a kind of control to measure the rest against. It only takes a few minutes for a heap of healthy cordgrass and black needle rush to become a set of numbers, a kind of bottom line.

After sampling three different areas where the ground is firm and the grass luxuriant, we move the field station back two hundred feet or so behind the ditch plug. The land suddenly starts sucking at our boots again, squelching and giving way beneath us as we plod in.

“An alternative name for my thesis might be Measuring Marsh Farts,” Dana jokes as he tries to keep his balance near a particularly pestilent pool covered in brown scum.

As the group prepares the fourth test site, a lanky research technician who hasn’t said much all morning points at the hollow of my throat and asks, “What’s with that necklace?”

For a second I am confused. I reach my hand up and fondle a silver hexagon hanging on a silver chain, a Christmas present I hadn’t taken off since receiving it. “Oh,” I say. “It was a gift. Why?”

“It looks like a shorthand representation of the atomic structure of benzene, the organic compound commonly found in crude oil,” he says. “It’s classified as a carcinogen in California.” Then he smiles and claps a hand on my shoulder. I have come to adore science-geek banter almost as much as I enjoy learning about the inner workings of these often-overlooked landscapes. Those who are devoted to tidal marshes are members of the same scattered and irreverent tribe. They are more at home thigh-deep in sulfurous mud than they are at the local shopping mall. Increasingly, as they bear witness if not to the end of the world then certainly to the end of one world, their humor has taken a turn for the macabre. “You have to laugh to keep from crying,” a geologist in the Everglades once told me.

Just then, the cavity ring-down mass spectrometer beeps, a warning that there is humidity in the lines. Benzene-man turns his back to me and faces the most pressing in a long list of problems.

The crew disconnects and reconnects the hoses. The beeping continues.

“Science,” Beverly says over her shoulder, “winging it every day.”

Once the water is cleared from the lines, and once we all eat a snack, the Plexi chamber is lowered over another square of marsh grasses. This time, nearly half of them are rotten. For a moment the world is silent as everyone leans in toward the bleached-out computer screen. The first reading is 1.55 parts per million (ppm) of methane, then 1.6 ppm, then 1.7 ppm. The group lets out a little yelp.

“It’s kind of twisted,” Beverly says with a chuckle, “but when we see that methane increase, it’s good, in a way, because it means that our hypothesis is at least partially correct.”

Just as Beverly and her students suspected, the rotting patch of marsh grass above the ditch plug is contributing more methane and carbon dioxide to the atmosphere than the same-sized sample plot of healthy grasses below. If you drill into a healthy marsh, you quickly encounter a network of rhizomes and black, iron-rich sediment. The sediment that cements most marshes together is so dense it doesn’t contain any oxygen. This anoxic environment is, in part, what makes marshes such good carbon sinks—whatever organic matter is stored there decomposes extremely slowly because it is never touched by air. But when salt water sits on a marsh and cannot drain, as was happening above the ditch plug, the cordgrass rhizomes begin to retreat and rot.

Beverly and her students suspect that the water infiltrating the marsh and now impounded by the ditch plug stimulate methanogens to suddenly spring into action, breaking down the stored organic matter. A kind of fermentation follows that causes the marsh to decompose from within, while also releasing methane and carbon into the atmosphere at an unprecedented clip.

Tug at a couple of ropes and the shape of the whole bundle changes.

“I’m not opposed to the idea of ‘monkey-wrenching’ the ditch plug,” says Laura Sewall, an eco-psychologist and the caretaker of the Bates-Morse Mountain Conservation Area. Laura is advocating for the kind of small-scale acts of eco-defense Edward Abbey encouraged to reestablish healthy hydrological patterns in the American West. Removing the ditch plug surely is one kind of solution: try to restore saltwater marshes to their original hydrology in the hope that they will be able to rise along with sea levels, as they have in the immediate historic past.

Whether that past is an appropriate analog for the future is a question worth asking. Sea levels are currently rising faster than they have in nearly three millennia. James Hansen, a former NASA scientist who now teaches at Columbia University, recently published a controversial paper that suggests that by century’s end the world’s oceans will likely be from six to fifteen feet higher. In it he also points out that the last time Earth was as warm as today was during the Eemian period, when sea levels rose thirty feet in a few short centuries. In which case no amount of monkey-wrenching will save the Sprague.

Dana stands next to the Science Box and does some rough calculations on his phone. “It looks like the area above the ditch plug is releasing significantly more methane than the area below.”

Beverly reminds me that methane, even in the long term, “is thirty times more effective at trapping heat than carbon dioxide, making it the most potent, if short-lived, of the world’s greenhouse gases.”

In that moment my desperation, of the monkey-wrenching sort, gives way to a resonant uncertainty about timing and timescales. If what is happening right now on the Sprague is also unfolding in other impounded tidal marshes the world over, then the likelihood that we will witness widespread marsh collapse goes up. But no one knows whether it goes up by a factor of one or one hundred, because humans have never recorded these kinds of events before.

What we do know is this: each particle of methane released into the air warms the oceans and the atmosphere, speeding up the rate at which glaciers and ice sheets are melting, which in turn accelerates the rate at which sea levels are rising, which diminishes the chances that a marsh will be able to adapt, raising the likelihood that it will rot and drown instead, which brings us back to the methane readings on that dimly lit screen on the edge of the Sprague: 1.55 ppm, then 1.6, then 1.7. Another feedback loop closed and amplifying.

*

After lunch, Laura and I split from the group for an afternoon kayak. We launch from her house, which sits just across the Sprague River on a small mound of land overlooking the marsh. Laura’s ancestors were some of the first Europeans to settle permanently along the Gulf of Maine. But Laura grew up about as far from here as possible without leaving the continental United States.

“When my parents got married, they drove west until they hit water,” she tells me as we dig our paddles in deeper and pass the breakers where the Sprague River pours out into the Gulf. “Too much family back here.”

I pause and watch a line of terns ride the air currents rising from the hollow waist-high waves as they curl and break. In the sheltered dunes between the beach and the marsh, a handful of piping plovers are beginning to fledge. Where the cordgrass gives way to the woods, pitch pines twist along the edge of a slice of gray granite that looks like a whale’s back.

The scene reminds me of the opening lines of one of my favorite children’s books, Robert McCloskey’s Time of Wonder. He writes, “Out on the islands that poke their rocky shores above the waters of Penobscot Bay, you can watch the time of the world go by, from minute to minute, hour to hour, from day to day, season to season.” As a child, I used to camp a hundred miles north of here on the quiet side of Acadia. Returning to this rocky coast makes me feel a little like my life is on repeat, that what has happened is happening again. But when I think about the preliminary findings procured on the marsh that morning, I realize that my familiarity and comfort are illusory: that the Maine of today is not the Maine of my youth.

Together, Laura and I cruise along the offshore spine of Sewall Beach, the largest undeveloped spit of sand in the state. Like the Sewall Woods in nearby Bath, the beach bears her family’s name. You can’t throw a stone around here without hitting something tied to Laura’s legacy. After decades away, working on environmental projects around the world, Laura returned to Maine, and has begun to act as a kind of liaison between the surrounding community and the marsh they live alongside, carrying news of the environmental changes taking place in the Sprague to the folks those changes will most immediately impact.

“The people who live out here from Phippsburg all the way to Small Point, they are starting to pay attention,” she says, “in part because the road out to the peninsula is already flooding during storms. They even formed an advisory board on ‘The New Environment’ and asked me to be a member. I am not sure what the committee will be able to achieve, but at least they are asking the right questions about mitigation, marsh migration, the impact on local fisheries, insurance, infrastructure, all that stuff.” Laura is easily one of the most well-informed and deeply committed citizens I have encountered since I started writing about sea-level rise. She filters every bit of information she receives, every lived experience, through the lens of climate change awareness, and in so doing, the seemingly cataclysmic somehow takes on a different sheen.

Together we travel between two distinct but continuous realms—the land-bound, waterlogged marsh and the open sea. Out here, the surface of the water is pure glass and spotted occasionally by the passing of a cloud high overhead. Every time I pull my paddle from the sea a tiny wave travels outward until it disappears. The farther out we go, the more the morning’s findings slough off of us. Something happens as I nose my little boat closer and closer to the blue-on-blue horizon, where water and sky become one indistinguishable force. It is as though I am paddling straight into the heart of a Rothko painting, or a landscape where all the traces of memory have been wiped away. The sun strikes the bay and fills my vision like a bell, and the last of the morning’s residual worry momentarily disappears.

It probably takes us half an hour to reach the Heron Islands, a set of four granite outcroppings about a mile from the shore. Laura, who spent most of the last decade of her life right here, has never been out this far before in her kayak. As we approach the islands, she tells me that the Herons aren’t known, despite their name, for their wading birds. Twenty feet to my right the snout-nosed head of a horse seal slowly rises out of the water. He stares up at me and I stare right back, watch the little wakes that radiate out from the place where his breath hits the sea.

This day is anything but ordinary, I think. Dulse-colored plumes of rockweed rumble beneath our bows as we slide between the largest of the islands in a slender channel of water no wider than a school bus. I look down into yet another little universe at the edge of things. The seaweed below waves brilliant maroon and a couple rock crabs scuttle sideways.

For a long time, Laura and I say nothing at all. Wordlessly, we head back toward the shore.

About halfway there, Laura dips her hand into the sea and says, “I have never felt it so warm so far out.”

And with that the spell is broken. My hand follows hers, breaking apart the clouds that slide across the surface of the sea. I pause, pull up memories of my childhood summering along the Maine coast. The Gulf was usually so cold I couldn’t bear to stay submerged for more than a second. Now, as I look down at my fingers comfortably wriggling below, I realize that this, too, has changed.

These days, all it takes is a little unusual warmth to make me feel nauseous. What I used to call climate anxiety has become more like a disease. I call it endsickness. Like motion sickness or seasickness, endsickness is a physical response to living in a world that is moving in unusual ways, toward what I imagine as a kind of event horizon. As a burble of bile rises from my stomach, a string of statements I have begun to hear more and more often in these parts replaces the unadulterated joy of our little afternoon adventure.

Because the Gulf of Maine is warmer than modern humans have ever witnessed, the bottom-dwelling cod, pollock, and winter flounder are pulling away from the shore. Because the Gulf of Maine is warmer than modern humans have ever witnessed, the shrimp fishery has been closed for years. Because the Gulf of Maine is warmer than modern humans have ever witnessed, phytoplankton are disappearing and green crab populations are exploding. Sea squirts are smothering the seafloor. Because the Gulf of Maine is warmer than modern humans have ever witnessed, the lobster are moving into deeper, cooler waters, keeping the lobstermen and women away from home for longer. Because the Gulf of Maine is warmer than modern humans have ever witnessed, everyone and everything that lives here is changing radically.

*

When we arrive back at Sewall Beach, Laura and I throw our exhausted bodies on the hot sand and stare up at the sky.

“We have to become more comfortable with uncertainty,” she says, as if reading my mind.

“Those who lived during the plague, I imagine, were probably a little uncertain about their future prospects,” I say with a snort. “Maybe we can try to channel them.”

Ten feet away, a seagull picks a clam from the surf, flies over the hardpack, then lets the shell fall. It stoops to the ground, picks the shell back up, rises, then releases it again, two, three, four times.

“For most of human history, mankind has not been half as sure of civil order or reliable food sources as we are today,” Laura says. “And maybe that sureness isn’t such a good thing. Maybe it dulls the senses, makes us less aware of what is happening right in front of us, right now.”

Finally, the shell the seagull has been struggling with breaks open. A slimy clam belly glistens on the wet sand. The gull calls to a friend and they feast together. For a moment I revel in the beauty of this basic ritual, happening right in front of us, right now.

Then I think about how the ocean is, like the marsh, one giant carbon sink. When it absorbs CO 2 , it becomes more acidic, which makes it difficult for bivalves, such as the clams and oysters that seagulls eat, to build their shells.

“What about those guys?” I ask Laura, gesturing to the duo digging into their clam belly.

Laura is dragging her fingertips through the sand. She doesn’t answer my question. Instead, she squints into the sun, stands, and says, “Let’s bodysurf a little before we head in.”

And that is exactly what we do. It is this moment that I will remember in the middle of winter when I wonder whether I made good use of my time, whether I lived fully in the few short months of riotous green here in the northeasternmost corner of the country. We played that afternoon, seal-like in the unusually warm surf. Our bodies were held aloft in the curl of a spitting wave, while behind the breakwaters, on the other side of Sewall Beach, salt water sat in the Sprague River Marsh, corrupting the land.

*

That night, as I lay in bed, I remember an ancient Hindu fable about the origins of the universe. It says that every four billion years, a flood completely dissolves the earth. Vishnu returns after the deluge in the form of a tortoise. On his back he places Mt. Mandara, which serves as a churning rod round which he wraps a snake. Gods and demons grab ahold of opposite ends. They tug against each other. The rod turns. The ocean roils, releasing amrita, the nectar of life. And the great earthly dance begins again.

I think then of a perversion of the story popularized during the British colonization of India. It picks up where the original left off, and is often recalled as a conversation between an Englishman and an Indian Sage.

Question: What does the great tortoise whose back supports the world rest upon?

Answer: Another turtle.

Question: And what supports that turtle?

Answer: Ah, Sahib, after that it’s turtles all the way down.

I think the exchange is designed to poke fun at the Hindu religion and also at any argument built upon an infinite regression. But I have always been inclined to find some truth embedded in the tale of turtles upon turtles, supporting our earth. When I hear the line “it’s turtles all the way down,” I don’t balk. Humans are nothing more than atoms come together to make life. The things we eat, the air we breathe—it is all made of the same manna. I think of the seagulls and the clams, and wonder what happens to the seagulls when the clams can’t make their shells. What happens to Mt. Mandara and the sea of milk if the tortoise’s back dissolves in an acidic ocean? Perhaps when it dissolves, the world floods and the cycle starts again. Perhaps that is what is happening right in front of us, right now.