The tempest began at 7 o’clock one morning this past June. It hadn’t rained for days, and by late afternoon, the forest floor had been drenched with 70,000 gallons of precipitation. Floods of salt water from the nearby Rhode River soaked the roots of the maples, beeches and tulip poplars. In this part of Maryland, near the Chesapeake Bay, downpours of such magnitude happen just once every ten years.
But this tempest was no natural disaster. Like the deluge in Shakespeare’s play, conjured by the duke-turned-magician Prospero, it was a human creation. In this case, TEMPEST stood for Terrestrial Ecosystem Manipulation to Probe the Effects of Storm Treatments, and the magician was Patrick Megonigal, a laid-back 62-year-old wetland ecologist in a flannel shirt, baseball cap and hiking boots.
That early summer storm was part of an extraordinary series of experiments that Megonigal is overseeing at the Smithsonian Environmental Research Center. He and his colleagues are simulating the conditions that will soon prevail along the world’s marshy shorelines: warmer temperatures, higher sea levels and elevated levels of carbon dioxide in the atmosphere. They’re creating the future so the rest of us know what to expect.
Everyone who studies forests knows trees have been dying in massive numbers, especially out west. At higher elevations, the main culprits are rising temperatures, drought and infestation. But in low-lying coastal places, there’s another problem: Sea level rise is saturating the soil, and storm surges are pushing salt water farther inland.
The idea for TEMPEST came from a colleague of Megonigal’s at the Pacific Northwest National Laboratory who’d been touring research projects on the marsh. “Do you think we can flood this forest?” he asked. Megonigal thought, “Why not?” So the scientists came up with a plan. They would flood two plots of forest, one with fresh water and one with salt water from the Rhode River, a tidal waterway emptying into the bay. Most flooding studies are limited to a square meter or so of land. TEMPEST would flood two areas, each encompassing 2,000 square meters (roughly half an acre).
Unleashing a tempest without the help of supernatural beings proved to be a major undertaking, so the Pacific Northwest National Laboratory sent a postdoctoral researcher, Anya Hopple, to help lead the project. Trees were outfitted with gas-collecting devices. Sensors were installed in the soil. LED lights were arranged so the scientists could find their way around in the dark. A company called Global Aquatic Research helped with the logistics, setting up giant tanks that could hold 160,000 gallons of water and connecting them to sprinkler systems through an intricate network of pipes.
The morning after the flood, Megonigal walked along boards through the wet forest, stopping to check in with various colleagues. They hailed from all over the world, some from as far away as China, Nigeria and Brazil. One group was studying the movement of the groundwater through a patch of now-salty soil. A few feet away, someone was pumping up liquid through a PVC pipe. Still others were measuring the gases coming out of the trunks of trees. There was a sense of excitement: Ecologists usually have to do their research on land that doesn’t belong to them, carrying solar-powered equipment in and out of the field. It’s rare to have the run of an entire forest, with devices connected to an electrical grid, and the chance to come back and gather new data from the same trees again and again.
In the lab at the nearby research station, James Taylor tunes played in the background as a group huddled around a tabletop pressure chamber. One by one, someone would insert a leaf to measure what was happening inside. “If you suck on a straw, there’s tension in the straw pulling the water up,” explained Nate McDowell from the Pacific Northwest National Laboratory. “That’s how water moves up a tree.”
Salt, like drought, forces trees to pull harder to get water. To see how much stress the trees were under after their first exposure to salt, scientists were measuring the tension inside each leaf, in units called megapascals. (Each megapascal equals about 145 pounds of pressure per square inch.) Studies show that at around -3 to -5 megapascals, air bubbles get into the stem and it can’t transport liquids anymore. Without water, the plant’s cells won’t be able to perform photosynthesis and the tree will die.
What the scientists are trying to do with TEMPEST, essentially, is to make the trees suffer. Over the course of a decade, they’ll unleash more floods and study the trees’ response. If that sounds harsh, the fact is that forests along the Chesapeake Bay are already dying and scientists are showing up too late to understand every step in the process.
A few weeks after the TEMPEST experiment, I visited one of those ghost forests along Maryland’s Eastern Shore. As I drove south toward the Blackwater National Wildlife Refuge, the scenery alternated between loblolly pines and glittering expanses of water that rose all the way up to the road, lapping at the edges of the asphalt.
Suddenly, around a bend, it came into view—a long row of dead trees. Their trunks were eerily gray and lifeless, standing erect with no branches. It looked as though a traveling band of giants had decided to leave their walking sticks in the ground and wander away.
Our planet is changing. That in itself is nothing new—seasons come and go, and so do larger cycles. The Earth’s orbit changes in ways that bring on ice ages or warming spells that last tens of thousands of years. Right now, though, something extra is happening, something that can’t be explained by the tilt or wobble of the Earth. This time, Megonigal says, “We, the people, are the wobble.”
One of the first scientists to see this coming was the Swedish physicist Svante Arrhenius. In 1896, he predicted that rising carbon levels in the atmosphere were going to make the Earth warmer. Arrhenius knew about the greenhouse effect, which had been discovered earlier in the century: Certain gases, like carbon dioxide and methane, trap heat. This is generally a good thing—it keeps our planet warm enough to sustain life—and Arrhenius thought turning up the heat even more would be an improvement. “By the influence of the increasing percentage of carbonic acid in the atmosphere,” Arrhenius wrote, “we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth.” (After all, the man did come from Scandinavia.)
Arrhenius expected the climate to change slowly, over the course of three millennia. In his day, the carbon cycle stayed mostly in balance. Whatever went up into the atmosphere from fires or volcanoes, for example, came back down again where it dissolved into the ocean, or trees pulled it in for photosynthesis. Carbon up, carbon down.
But the Industrial Revolution kicked the carbon-up part of the cycle into high gear. Suddenly, people were burning more fossil fuels than ever before, releasing carbon that had been stored underground for millions of years. In the late 1950s, when scientists started recording the amount of carbon in the atmosphere, it was about 315 parts per million. In 2019, it passed 410 parts per million. That same year, humans added around 43 billion U.S. tons of carbon to the atmosphere. The pandemic put a dent in fossil fuel use, but we still sent up more than 35 billion U.S. tons of carbon each year in 2020 and 2021.
The effects can be seen most dramatically in the Arctic, which is warming almost four times as quickly as the planet as a whole. That’s because melting glaciers and ice sheets launch a heat spiral: When there’s less ice, there’s less white surface to bounce away the sun’s rays. The dark ground and water left behind absorb heat, which melts the remaining ice even faster. All that melting ice is contributing to rising sea levels and shifting the currents in the ocean. An uptick in fires in places as far apart as England and Australia, thawing permafrost in Alaska, deadly heat waves in India, a higher proportion of intense storms—all of these are signs of global climate-control systems losing their equilibrium.
Global warming was already a hot topic half a century ago when Bert Drake, a retired plant researcher, was starting his career. Drake, who is now 87, remembers his colleagues talking excitedly about the changes: “Plant physiologists had a very simplistic way of dealing with rising CO2: ‘No problem, plants love it! The more CO2 you’ll give them, the more they’ll grow.’”
This was true for crops in carefully regulated greenhouses. But, Drake wondered, what would extra carbon dioxide do to plants that were just out in the field growing, with no one adjusting the temperature and humidity to help them thrive? He’d recently started working at the Smithsonian Environmental Research Center, and he was especially interested in the hardy grasses and sedges growing by the Chesapeake Bay. So he pulled together funding, and in 1987, he launched what would become the world’s longest-running study of wetlands and rising carbon dioxide.
It didn’t take long for Drake to see results: The plants that had extra carbon dioxide pumped into their hexagon-shaped chambers indeed grew much better than control plants nearby—they had more shoots and foliage and survived longer into the fall than their counterparts did. Drake also discovered something his colleagues hadn’t anticipated: The extra carbon dioxide made the plants more efficient in how they used nitrogen, managed water and respired oxygen.
At a congressional hearing in 1992, Drake spoke so glowingly about his experiment that Al Gore, then a senator from Tennessee, became slightly alarmed. “He said, ‘Well, this place doesn’t represent the tropical rain forest—does it, Dr. Drake?’”
Drake good-naturedly let it go. “I didn’t want to get into a long dialogue with Al Gore about things that we know or barely know in front of all my colleagues,” he told me. But his real answer would’ve been more nuanced. The study at the Chesapeake marsh did in fact represent all plants. If trees in the rainforest were exposed to higher levels of carbon dioxide, they too would absorb more carbon.
Yet Drake knew what Gore was getting at. Rising levels of CO2 are going to make the planet hotter, and the extra heat in the already steamy tropics will more than cancel out whatever plants might gain from all the extra carbon dioxide.
It’s not just that heat can cause drought. Even in wet areas, high temperatures can stifle photosynthesis. This has been well documented, Drake said: “Once the temperature gets above about 30 degrees”—Celsius, that is, or around 86 degrees Fahrenheit—“crop production begins to drop precipitously.” From there, the plants’ productivity goes down about 10 percent with each additional degree Celsius, or two degrees Fahrenheit. “Now that’s startling,” Drake said. “To see that in massive amounts of data collected over many, many years for these crops all over the United States—I mean that’s a remarkable finding.”
Drake’s study is still up and running today, but 12 years ago, Drake retired and handed it over to Megonigal. By that time, the plants that were getting extra carbon dioxide weren’t thriving as much anymore, and the benefits are continuing to diminish. Earlier this year, Megonigal and his colleagues published a paper suggesting that as the sea level rises more and more quickly, the resulting floods are stressing the plants, which offsets the advantages they were getting from the extra CO2. The marsh is now known as the Global Change Research Wetland, and Drake’s study has been joined by a host of other experiments that preview other aspects of our climate future.
One morning in early May, I drove an hour east from Washington, D.C. for a visit. The road cut between farms and horse pastures and then wound through a dense forest until I reached the little green research station at the water’s edge.
The surrounding grasses and sedges used to be dead and brown at the beginning of May when the scientists resumed their research for the year. But when Megonigal greeted me, he pointed out that some of the marsh grass was already green. He gestured toward a shrub called Iva frutescens or high-tide bush. “It’s been expanding, and I am convinced that that’s another global warming signal,” he said. “Because really bitter-cold winters kill it. And we haven’t been getting many of those.”
The area where we were standing had once been open water. Then, about 4,000 to 6,000 years ago, the sea level rise from the last ice age started slowing down and plants along the coastlines were finally able to put down roots. Those plants trapped sediment and formed spongy ground that lifted them up above the waterline. The sedges and grasses growing in wetlands today live on peat built up by their predecessors. This is the genius of wetlands: “They engineer themselves out of drowning,” Megonigal says.
This knack for trapping sediment is also why peatlands are exceptionally good at keeping carbon in solid form. The dead plant matter in the water stays underwater, where it doesn’t decompose the way it would on dry land. Bogs, marshes and tropical swamps built on peat store twice as much carbon as all the world’s forests combined, even though peatlands cover only 3 percent of the land on Earth while forests cover more than 30 percent.
At most wetland research sites, scientists (and any visiting journalists) have to put on waders and chart a course through the muck. But the Global Change Research Wetland has a long, many-branched plastic boardwalk connecting all of its different experiments. Along that path, I found Genevieve Noyce, a 35-year-old researcher in a purple Patagonia fleece. She was standing next to a study she’s been overseeing since 2016. Known as SMARTX (short for Salt Marsh Accretion Response to Temperature eXperiment), it’s the first simulation of warming trends in coastal wetlands. A series of infrared lamps and cables in the ground are heating patches of the marsh to different temperatures—about 3, 6 and 9 degrees Fahrenheit above their natural surroundings.
The patch of marsh that’s being heated just a few degrees is flourishing. The roots are growing better, keeping more carbon in the ground and adding land elevation. This seems to line up with what’s been happening in real life—the slight rise in local temperatures that’s making the marsh come alive earlier each spring. I mentioned this to Noyce and she agreed that the marsh appeared healthy: “You look around and you see green, happy plants.”
The problem is that temperatures are only going to keep rising. Data from SMARTX shows that the patch of marsh being heated 9 degrees isn’t doing well at all. This has to do with the invisible creatures that live in the soil. Communities of microbes—bacteria, protozoa, archaea, fungi and microscopic worms—generally help the marsh by breaking down minerals so plants can use them as nutrients. But as the temperature increases, the microbes become more active. In the warmest patches of SMARTX, they’re so active that they’re breaking up the soil itself, leaving holes. Pins in the ground indicate that the marsh has stopped gaining ground. In real-world terms, this means that once temperatures get high enough, the microbes will start destroying the soil faster than the plants can engineer themselves above the rising sea level. The marsh will drown.
Near SMARTX was a series of round chambers with colored bands at the tops—red, yellow, sky blue and lime green. The whole thing looked like a modern art installation, but it was part of a study called GENX (Greenhouse gas Emissions NeXus) that Noyce launched last year. The ground inside those color-coded chambers is also heated to different temperatures. But here, Noyce is getting a precise read on the microbes. When the microbes get more active, they generate more methane, a molecule of carbon and hydrogen that’s an even more potent greenhouse gas than CO2. They also break up compounds in the soil, releasing solid carbon back into the atmosphere. Every ten minutes, a robotic lid on each of those chambers clamps down and sends gas measurements to Noyce’s computer.
Farther out on the boardwalk, I joined Gary Peresta, a 64-year-old engineer who oversees the equipment at the research marsh. With his bushy beard and twinkling eyes, he resembles Jerry Garcia, the late frontman of the Grateful Dead. Peresta started working at the marsh in 1990, after studying the effects of carbon dioxide on cotton crops for five years at the Department of Agriculture. “I’ve been measuring CO2 myself, with my own two hands, for the last 37 years,” Peresta told me. “In 1985, it was less than 340 parts per million. It’s over 410 parts per million now.” He paused for emphasis. “The amount of carbon in the atmosphere has gone up 20 percent just in the course of my career.”
We stopped at the edge of the Rhode River, one of the many waterways feeding the Chesapeake Bay, the largest estuary in North America. By the time the first English colonists arrived in the early 1600s, humans had already been living by the bay for at least 11,500 years, taking advantage of the rich soil and the abundant clams, crabs, oysters and other shellfish. These days, overfishing, water pollution and development have taken a heavy toll on Chesapeake Bay wildlife, but fishing and recreation still bring in billions of dollars each year. Runoff from the marshlands, which cover more than 700 square miles, plays a vital role for all the creatures that live in the bay.
Peresta kneeled by the water and showed me instruments that measure what scientists call blue carbon—that is, organic carbon that’s stored by marine ecosystems—as it washes into the bay. (The carbon isn’t actually blue; the color is meant to evoke the watery places where it’s found.) He pointed out small containers of grass, the setup for another study that’s monitoring how plants fare at different water levels.
It’s not easy for Peresta to keep all this equipment running in the wild. He’s had to use trial and error to stop large plant chambers from blowing away, and meddling muskrats present their own challenges. But he loves the way nature makes its presence felt everywhere. When a lizard with a blue tail rushed in front of our feet, he told me it was a skink. When we opened a wooden equipment cabinet, he warned me, “There are snakes living in there.” Sure enough, there was a snake, coiled above a box of industrial-sized staples.
Back at the research station, Peresta showed me a closet filled with his guitars; he performs with local bands on the weekends. I asked him to play me a song and, in keeping with his appearance, he strummed the opening chords to a Grateful Dead tune. I listened to him sing as the grasses and reeds stretched out in the distance behind him: “Come hear Uncle John’s band by the riverside / Got some things to talk about, here beside the rising tide…”
Imagine a desktop globe that worked almost like a crystal ball. You could zoom in on any region and find out what the climate would be like there in the year 2035, say, or 2071. This is, figuratively, what scientists around the world are hoping to create—a detailed worldwide predictive model encompassing earth, water and air.
So far, most climate models have focused on either land or ocean, leaving out the wetlands in between. That missing information is crucial, says Daniel Stover, the acting director of the U.S. Department of Energy’s Earth and Environmental Systems Sciences Division. The slender strips where land meets water are filled with dynamic processes that influence the whole planet. “In coastal areas you have this weird hodgepodge where everything comes together,” Stover told me. His department has been investing in the Global Change Research Wetland since the 1980s.
Until recently, modeling technology was only able to represent areas of about 100 square kilometers, roughly the size of the Bronx. That’s not precise enough for narrow, complex areas like wetlands—it would be like trying to represent a single face as part of a low-resolution photo of a large crowd. The newer models are much higher resolution: The hope is that it will soon be possible to zero in on a single square kilometer, about the size of the Bronx Zoo rather than the entire borough. As Stover put it, “now you can really represent all these fine-scale processes”—the difference, for instance, between the soil salinity in a ghost forest and in a healthy stand of pines in the next cell over.
In 2020, Stover’s office launched a new program called COMPASS—short for Coastal Observations, Mechanisms, and Predictions Across Systems and Scales. Most of its contributors come from big national labs; the Pacific Northwest National Laboratory is the lead institution. Megonigal is the chief scientist for the program’s field studies. (The TEMPEST experiments are part of the larger COMPASS program.) “Everybody in the world knows who Megonigal is, if you study wetlands,” Stover said. “So he brings a lot of credibility to the study.”
So far, COMPASS is focusing on places where land meets especially large bodies of water: saltwater sites along the Chesapeake Bay and freshwater sites along the Great Lakes. But there are wetlands in all 50 states, even seasonal wetlands in the arid deserts of Nevada and Arizona. Once scientists gather enough information, their models will be able to make predictions for different kinds of wetland, from bogs in Alaska to swamps in Mississippi.
“As scientists, we’ve not done a good job communicating this term ‘climate change,’” said Kennedy Doro, a COMPASS contributor at the University of Toledo. Doro grew up in Nigeria, where the changing climate is difficult to ignore: People are dying from both extremes of drought and flooding. There’s also a range of other issues that come from poor environmental management. Doro got interested in groundwater because he’d spent so much of his childhood getting sick. “Every three months, I was back in the hospital, even as a teenager, because of diarrhea and cholera,” he said. Now Doro is a hydrogeophysicist who studies how water moves through the soil.
Whenever skeptics tell Doro that natural processes are responsible for global warming, he says, “Correct. I agree. I’m not debating that. What I’m telling you is, we are trying to understand these connected processes, both human-induced and climate-induced. Because it’s now happening at an intensity and a rate that we just can’t handle.” The problem of climate change, as Doro defines it, “is about having more change than we can manage at the time.”
For those living near the Chesapeake Bay, a preview of some of these challenges is available about a thousand miles down the coast, in South Florida. Sea levels along those sparkling beaches have been rising over the past century at ever-increasing rates. On Virginia Key, an island just across the bridge from mainland Miami, sea level has risen eight inches since 1950, and it’s rising faster and faster—the rate is currently up to one inch every three years.
At the same time, more and more of the region’s storms are reaching Category 3 to 5 strength, as currents in the warm, humid air down south brew more rain-laden clouds and push them up the coast. In September, Hurricane Ian killed more than 100 Floridians and left more than 1.7 million without power. Homes in the state have been so pummeled by the elements that many private insurers have raised their rates or pulled out of the state entirely. In 2002, the Florida legislature established an insurer of last resort, Citizens Property Insurance Corporation, but it doesn’t cover flood damage. More than half the private homeowner insurance companies still in the state now have ratings too low to comply with federal mortgage loans.
So far, ideas for protecting Miami have been a tough sell. In 2020, the Army Corps of Engineers unveiled a plan for a wall that would block views of Biscayne Bay. Not surprisingly, the proposal was unpopular. Miami City Commissioner Ken Russell complained to the New York Times: “The $40 billion in assets you’re trying to protect will be diminished if you build a wall around downtown because you’re going to affect market values and quality of life.”
If scientists had more data on everything that’s happening to the land, water and air, we might be able to craft solutions that would be better tailored to specific places. Those solutions will most likely include a mix of technical and natural approaches.
“Wetlands are amazing,” said Fernando Bretos, a marine scientist from Miami who works as a program officer at the Ocean Foundation. “When a storm wave comes, they slow down the impact and absorb all that energy.” And unlike concrete walls, beachfront plants can adapt to waves, building themselves up and expanding as they absorb more material from the ocean.
In 2013, Bretos started a dune restoration project on Virginia Key. Working with the city and volunteers, Bretos cleaned up the area and planted 37,000 native plants. “They looked like hair plugs,” he said. Most of the seedlings were sea oats, a hardy species that can be found all the way up the coast to New Jersey. As the plugs matured, their exceptionally long roots pushed down deep, anchoring the dunes. When Hurricane Irma whipped through the area in 2017, the plants protected the shoreline from the pounding waves. “In fact, the dune trapped more sand and became bigger,” Bretos said. “Whenever I fly out of Miami, I see that site from the plane. I get goose bumps every time.”
The full force of climate change may not have hit the Chesapeake region yet, but the signs are becoming more pronounced. Homeowners complain of heavier rains, which can bring more flooding—the Northeast U.S. now gets about 70 percent more rainfall during the heaviest storms than it did back in the 1950s. Sea levels in the area are a foot higher than they were a hundred years ago, and they’re projected to rise as much as five more feet in the next century.
But Bretos has seen communities combat similar problems by restoring wetlands along the coasts of Florida, Mexico and Central America. Some of the projects have received funding from big corporations like FedEx and Wells Fargo, along with governments and nonprofit organizations. “We can slow this down if we really commit,” he said. “Climate change is a human-driven problem. It has human-driven solutions. Remember the ozone hole—we fixed it in ten years. Why? Because we flipped the script and we did something about it, right?”
At the end of Shakespeare’s Tempest, Prospero vows to give up his powers and let nature regain its balance: “I’ll break my staff, / Bury it certain fathoms in the earth, / And deeper than did ever plummet sound / I’ll drown my book.”
We can’t make that kind of promise. Even if we stopped burning fossil fuels today, it would take decades for global temperatures to stabilize. And as the leading journal Science reported in September, if our planet’s average temperature warms to more than 2.7 degrees Fahrenheit above what it was before the Industrial Revolution, it could trigger irreversible changes around the globe. An analysis published in 2021 showed that Greenland’s ice sheet could soon lose enough mass to set it on an irreversible path of accelerated melting. Another study last year reported signs that the Atlantic Meridional Overturning Circulation—a crucial ocean system that brings warm water up north and cool water down to the tropics—is heading toward collapse. And in March, research based on satellite data indicated that three-quarters of the Amazon rainforest could turn into dry savanna within the next few decades.
Given such dire predictions, I was often surprised by the cheerfulness of the wetland ecologists I met during the many hours I spent talking to them over Zoom or standing beside them in mucky swamps. They told me they feel depressed when they see clear signs of demise, like the way extra carbon is acidifying the ocean and destroying coral reefs in Belize. But they wouldn’t be able to do the research they’re doing if they were paralyzed by despair. They have to be realists but they can’t afford to be Cassandras.
Their line of work also attracts people who enjoy waking up before dawn and spending time outdoors. As postdoctoral fellow Stephanie Wilson told me with a smile, while we were ankle-deep in mud at the ghost forest, “We love being out here. We stop for every little turtle.”
But there’s something else behind their cheerfulness—a spirit of exploration. I saw it on Megonigal’s face as he called out a record-breaking methanogen reading to his colleagues, or when someone told him that a rainfall had pushed salty water deeper into a tree’s roots. The data itself might have been foreboding, but it was still data, and the process of gathering it was still exhilarating. And more knowledge ultimately means more power to make large-scale changes.
On my last visit to the research wetland at the end of July, I brought along my 11-year-old son. He grew fascinated by the work of Adam Langley, a Villanova University professor who set up a nitrogen-oriented experiment at the marsh in 2005 and still comes back frequently to check on it. Langley has kids of his own and he was indulgent as my oldest child bombarded him with questions: What does nitrogen do, and how is sea level measured in the middle of all those tides and waves, and why hasn’t anyone invented magnetic cars yet? When Langley described the mangroves he studies in Central and South America—floating islands with tangled roots tethering them to the ocean floor—my son asked whether they looked like the trees on Yoda’s planet in Star Wars. The 46-year-old professor gave a boyish laugh and replied, “Yeah, exactly!”
Humans are born scientists—we come into the world that way. All the innovations that launched the Industrial Revolution, all the machines that have made our lives so much better, came from the minds of people who were once curious kids. So did the high-tech instruments that scientists are now using to collect data and predict the future. If anything can save our species, it will be this irrepressible drive to investigate and discover, to create and collaborate—and maybe, for the sake of our own curious children, to leave the world better off than we found it.