ONE MORNING LAST SEPTEMBER, I kayaked to an island in a lake on an island in the sea in Southeast Alaska. On this island-on-an-island—managed by the US Forest Service but part of the homelands of the Tlingit people—I rested against the trunk of a cedar that I guessed was a few hundred years old. It didn't seem as ancient as some cedars I had seen around there, since its trunk spanned three or four feet instead of six or seven. But it was in a forest that had never been cut, and that was what mattered. I was there to remember what the old-growth temperate rainforest of Southeast Alaska is like.

A decade earlier, I had led canoeing and hiking trips in Southeast Alaska, and the experience had expanded my definition of abundance. In addition to having more biomass per acre than any other ecosystem in the world—roughly three times as much as that of tropical rainforests—its forests are home to some of the world's densest concentrations of black bears, brown bears, bald eagles, and wild salmon. It's a region where wolves den in the roots of ancient trees, whale songs echo through moonlit forests, and the glaciers are bigger than some countries. Even the precipitation is decadent. Up to 160 inches of rain and snow a year fall on the coasts, with some mountains receiving more than 400 inches.

Tucked between the coast and the mountains are groves of enormous, magnificent trees: Sitka spruce, western red cedar, yellow cedar, and western hemlock that can soar to 200 feet and live a thousand years or more. The island I'd reached by kayak was too waterlogged to grow such giants, but it was otherworldly in its own way. Trees of all ages and sizes stood and leaned and lay beneath layers of moss—starbursts of moss, cushions of moss, moss that draped and dripped and clung. Life grew upon life, ferns upon mosses upon trees upon logs, and all of it was woven through with death. The fall breeze carried whiffs of decaying wood and rotting salmon. A raven croaked in the distance. A mink slid off a log and disappeared into the lake.

    Clad in wool, fleece, and Gore-Tex, I had a hard time remembering that temperatures at home in Colorado were breaking heat records, and that wildfire smoke was choking parts of the Pacific Northwest, and that another tropical storm was barreling toward the Gulf Coast. Each disaster was intensified by a climate roughly 2°F warmer than it was at the start of the Industrial Revolution.

Stopping the planet from warming further requires us to cut back on fossil fuels and adopt greener technologies as quickly as possible. Just as important, though, it requires that we protect mature forests from logging—especially the one that surrounded me. The 16.8-million-acre Tongass National Forest covers nearly 80 percent of Southeast Alaska and holds 2.8 billion tons of carbon—nearly half of all the carbon stored in the United States' national forests. No tree-planting scheme, no matter how ambitious, could ever compare.

For decades, the fate of this bulwark against climate change was batted like a Ping-Pong ball from one presidential administration to the next. Republicans tried to increase logging; Democrats tried to curtail it. Rules and policies changed so often that anyone trying to keep track was apt to suffer whiplash. The Tongass Timber Reform Act and the Roadless Rule (which prevents new logging roads in roadless areas) tempered the pace of clearcutting, but at the start of 2021, the Tongass was the last national forest in the country where private companies regularly razed swathes of old-growth trees. Then, in July 2021, President Joe Biden made an unprecedented announcement that his administration would stop all industrial-scale old-growth logging in the Tongass, effective immediately.

Two months later, I flew in an eight-seater airplane to Prince of Wales Island, rented a 1996 Toyota pickup and a red sea kayak, and paddled across a lake to an island that had never seen a chainsaw. There, after hours of traveling through crowded cities and smoky skies, I breathed. The Tongass had been spared. I inhaled the cool fall air, and exhaled something like gratitude.

SMOKE ROSE FROM the door of a smokehouse and into a cloudy evening sky. Together, the smoke and the clouds drifted over Port St. Nicholas, a horseshoe of seawater cradled by emerald mountains. Salmon flung themselves from the shallows as if flagrantly displaying their aliveness in the final moments before they spawned and died. In the smokehouse, strips of sockeye hung in rows, as red as fire.

The evening I visited, a 28-year-old Haida and Tlingit woman named Marina Anderson squatted next to a heap of smoldering embers, her red hair nearly brushing the ground. As a teenager, she had to petition her high school to let her graduate because she had missed so many classes while putting up salmon and other traditional foods. The night before I stopped by, Anderson had been hanging fish until three in the morning, and she would be up just as late tonight rotating them.

During the day, she had participated in hours of virtual meetings for her work with the Southeast Alaska Tribal Youth Commission, the Sustainable Southeast Partnership, and several other organizations. She was so tired that when she closed her eyes, she saw the little squares of Zoom participants on her computer screen.

"I spend a lot of my time researching missing and murdered Indigenous women and having conversations about circle peacemaking and ocean activity," Anderson said, leading me from the smokehouse to a small gravel beach. "You name it, we're talking about it—housing shortages, mental health disparities in our communities. And we know the answer to everything: It's to have access to our traditional ways of life. And the only way to have that is to have intact forest."

    Since these forests first sprouted from the bare ground left by receding glaciers thousands of years ago, the well-being of Tlingit, Haida, Eyak, and Tsimshian peoples has been inseparable from that of the trees. At one time, canoes, coffins, cradles, and clothing all came from the forest, as did medicine, art, food, and nearly everything else people needed to live. Europeans may have seen the land as untouched—"pure wilderness," as John Muir wrote in Travels in Alaska—but in reality it was as carefully tended as a garden, its biodiversity nurtured by its human inhabitants. As a Tlingit elder named Mike Douville told me, "You don't have to destroy the land to live here."

With the establishment of the Tongass National Forest in 1907, though, the fate of Lingít Aaní—as the region is known in the Tlingit language—began to shift. In the 1950s, the Forest Service began issuing heavily subsidized 50-year timber contracts to local mills to jump-start economic growth. Logging camps morphed into permanent towns, and companies began systematically cutting the biggest trees to feed into pulp and saw mills. The passage of the Alaska Native Claims Settlement Act in 1971 only ramped up the pace of destruction. Under ANCSA, Alaska Natives formed corporations in which each tribal member was a shareholder. Corporations made money in part by developing natural resources on their ancestral lands. In Southeast Alaska, that meant cutting old-growth forest.

The Forest Service, the State of Alaska, and regional and village Native corporations together razed 800,000 acres of trees. Although up to 5 million acres of old growth remains—making the Tongass the largest tract of relatively intact temperate rainforest in the world—loggers targeted the biggest, oldest stands. More than half the region's large old-growth trees have been felled; on northern Prince of Wales, the figure is as high as 93 percent.

Like many men of his generation, Marina Anderson's father worked in the timber industry, first as a logger and then as a road builder. "When he died," Anderson told me, kicking the gravel with the toe of her rubber boot, "at least what he had told me was that he had helped construct every road that was open at the time on the island."

Today, Prince of Wales is dissected by more than 2,500 miles of roads—more than the rest of Southeast Alaska's combined. The island, which is nearly as big as Puerto Rico, is sometimes referred to as the Tongass's tree farm—or its sacrifice zone. Flying over it, I was astonished by the scale of past logging. The mountains looked as patchy as a teenager growing a beard.

"The media are quick to say, 'Well, as Native people, you logged your own land,'" Anderson said. "And we did. But that was a different generation, and we're in a different time now. We're learning from those mistakes. And we've been told by [Native] loggers themselves: 'No more. Do not do this again, at any cost.' To hear their voices trembling. . . . They're heartbroken because they know what they did to our land just to put some crappy Western food on the table."

After our conversation on the beach, Anderson sat in front of the smokehouse, whittling a bowl and talking with her older brother about different methods for smoking fish. The evening was quiet. The water in the bay reflected the shifting silver clouds.

Suddenly, three orcas surfaced not far offshore. "Mom!" Anderson yelled. "Killer whales!" Her mother rushed outside in a housedress, and all of us faced the ocean, watching the orcas' black fins slice through the water like knives. It looked like they were cutting open the sky.

BEFORE COMING TO ALASKA, I'd called Dominick DellaSala, a conservation biologist with a project called Wild Heritage, sponsored by the Earth Island Institute, who has studied the Tongass for 30 years. "One of the biggest contributors to the warming of the planet is deforestation," DellaSala had told me, his Brooklyn accent untempered by decades in the Pacific Northwest. "And we're finding that temperate rainforests are incredibly carbon-dense."

Like all trees, those in temperate rainforests absorb atmospheric carbon dioxide through photosynthesis and store it as sugar in their wood, the same way humans store excess sugar in our bodies. But unlike, say, Rocky Mountain pine forests, which require regular wildfires to regenerate, the Pacific temperate rainforest has evolved with few large-scale natural disturbances. Windstorms and landslides occasionally topple patches of trees, but major landscape-level disturbances are rare. Combined with moderate temperatures and abundant rainfall, this stability allows the trees—and the ecosystems they anchor—to accumulate an exceptional amount of carbon. On average, the aboveground carbon density in the Tongass is 70 metric tons per acre. In the woods of the Colorado Rockies, it's eight tons per acre.

And that's only the carbon above the surface. In true old growth, thousand-year-old living trees grow on top of thousand-year-old dead trees, with even older trees in the soil beneath those. Each year, tons of fallen needles accumulate on the forest floor, each a tiny capsule of carbon. The roots snaking through the soil are veins of carbon. The moss smothering it all is rich in carbon. The ground itself is a storehouse, holding carbon that hasn't seen the light of day for thousands of years.

When a forest is cleared with heavy machinery—tearing up not only the trees but also the ground beneath them—roughly two-thirds of this carbon is released into the atmosphere. Between 2000 and 2017, logging, agriculture, droughts, and wildfires reduced global tree cover by nearly a billion acres. Each year, deforestation and other forms of land degradation release about 4 billion tons of CO2—a significant portion of the roughly 40 billion tons of carbon pollution that human activities emit annually. Stabilizing the climate requires that we reduce and eventually zero out industrial and agricultural emissions—while somehow capturing whatever remains.

Trees offer one of the simplest and most effective ways to capture that carbon. Already, healthy and intact forests, peatlands, grasslands, and ocean ecosystems absorb about 6 billion tons of CO2 annually. In a 2019 paper in the journal Science, an international research team reported that planting half a trillion trees could sequester more than 200 billion tons—offsetting more than five years' worth of total global emissions. The research spurred numerous reforestation initiatives, including corporate tree-planting campaigns and the Republican-sponsored Trillion Trees Act in the United States. People have even proposed vast afforestation schemes to plant trees where there are none, like the Great Green Wall, which would span the African continent between the Sahara Desert and the Sahel.

While such initiatives aren't inherently bad, many scientists worry that they miss the mark. Some argue that they result in arboreal mono­cultures, which are more susceptible to diseases and less hospitable to wildlife. Others take issue with the idea that trees need to be planted in the first place. "A planet with a trillion more trees would be a much better place," journalist Fred Pearce writes in his book A Trillion Trees. But planting them is unnecessary: "Nature will mostly do it for us. And she will do it better. If we stand back and give them room, forests will regrow."

Most important, tree planting can distract from the work of protecting trees that are already growing. Although some studies suggest that fast-growing young trees absorb carbon more quickly than old ones, old forests still hold the most carbon because a tree's capacity for carbon storage accelerates as it ages. Keeping mature forests standing remains the most effective land-management strategy for preserving biodiversity and preventing the climate from spiraling out of control.

New research also shows that mature forests may be more resilient to climate change than young ones, because very old trees contain specific DNA that has helped them survive for so long. If those trees are felled and hauled away before their genes can be passed on, the forest that grows up in their place may be more vulnerable to diseases and extreme weather.

For all these reasons and more, DellaSala and others believe not only that the Tongass's remaining old growth should be protected from logging but also that much of the forest should be preserved as a climate refuge, managed for its carbon-storage capability. "We're proposing a strategic national carbon-reserve network," DellaSala told me. "It's the flip side of the oil reserve. It's protecting the carbon that's sequestered in old forests and large trees on federal lands nationwide, and the best place to start is on the Tongass."

Ceasing large-scale old-growth logging doesn't mean sacrificing the region's economy. The timber industry was declining long before President Biden's announcement: An average of 35 million board feet have been cut from the Tongass annually in recent years, compared with 520 million in 1980. Fewer than 1 percent of people in the region now work in timber. And last year, the regional Alaska Native corporation Sealaska announced that it would stop logging its 362,000 acres and generate revenue by selling the carbon credits from roughly half that forest to oil and gas companies to offset their emissions. The 9.3 million tons of carbon dioxide in Sealaska's forest are reportedly worth $100 million. In contrast, the Forest Service has lost $1.7 billion of taxpayer money subsidizing its Tongass timber sales since 1980, including $16 million in 2019 alone.

TWO-AND-A-HALF-MILE CREEK sings as it runs over cobbles and beneath knobby alder roots. It sings as it falls over logs, slips past skunk cabbage, and pools beneath dinner-plate-size leaves of devil's club. Its song carries downstream to the Klawock River, which once hosted tens of thousands of spawning sockeye salmon, and into the ocean. There, its vibrations reach some of those salmon's descendants. It calls them back to the forest.

When salmon in Southeast Alaska return to their natal streams each summer and fall, they carry in their bodies nitrogen, phosphorus, and other nutrients accumulated from years of living at sea. After salmon spawn and die, those nutrients become part of the soil, fertilizing trees on the river's banks. After bears, wolves, and other animals eat salmon, they wander through the forest and defecate, spreading fertilizers farther inland. According to one study, trees near salmon-bearing rivers grow three times faster than trees near rivers without salmon. Some naturalists even speculate that Southeast Alaska's rainforest exists because of the salmon.

The region's human and ecological communities, in other words, depend on its salmon runs, which is why much of the work being done to repair the damage of past logging is focused on streams like Two-and-a-Half-Mile Creek. In the 1980s, before environmental regulations required loggers to leave a buffer around waterways, a Native corporation leased the area to various logging companies, which clearcut the area around the creek, robbing the stream of the shade and "woody debris" that anadromous fish need to survive. Streams across the region suffered a similar fate; sockeye salmon populations in the Klawock watershed are now a fraction of historic levels.

But as tribal forester Jon Carle of the Organized Village of Kasaan led me along the narrow creek, he spotted what looked like a salmon fry darting upstream. "Fish!" Carle called out, grinning. "He made it far!" In 2021, Carle and his crew began adding logs and other obstructions to Two-and-a-Half-Mile Creek to mimic what it would have looked like before logging. The Forest Service, environmental groups, and tribal entities are undertaking similar projects across the region. The salmon fry is the first Carle has seen this far upstream—evidence that this particular restoration project is beginning to work.

After checking out Two-and-a-Half-Mile Creek, I followed crew leader Quinn Aboudara (Marina Anderson's brother) deeper into the woods. In this lush climate, so many saplings sprout naturally after a clearcut that, rather than replant trees, restoration crews are tasked with thinning the closely spaced second growth. The forests that regrow after a clearcut are colloquially known as "doghair," because the trees are as tightly packed as the guard hairs on a husky. Walking through doghair is one of the most miserable bushwhacking experiences a person can have. Little grows or moves except clawing, scratching branches. There are no berries, no deer, hardly any songbirds.

As crew members peeled off into the monotonous doghair, following a series of empty energy-drink cans hung from branches to mark the way, the air began to tremble with the sound of chainsaws. By felling hundreds of fist-width trees a day, Aboudara and his crew space out the doghair enough to let other vegetation grow, which in turn allows deer and other wildlife back in. Reducing competition for light also lets the remaining trees mature more quickly. Aboudara pointed out one tree that had fallen naturally; the area around it was already green with moss and blueberry bushes, in contrast to the lifeless doghair.

"We're accelerating the natural process," he explained. "If we do our jobs right, most people [in the future] won't be able to tell the difference between this and historical old growth."

How long this will take is debatable: It could take a thousand years for a forest to truly recover and several hundred to recapture the carbon released by clearcutting. Restoration efforts could increase carbon storage by helping the forests develop old-growth characteristics more quickly. But for Carle, Aboudara, and the rest of the crew, that's not the point. "This is legacy work," Carle said. "I'm not trying to figure out how, before I die, I can get these trees to be so big I can harvest them. None of this is going to matter in my lifetime. But it will definitely change—bring back the fish, bring back the trees, bring back the wildlife, bring back all the things we used to have an abundance of that have been diminishing."

SOUTHEAST ALASKA'S extraordinary carbon-storage capacity doesn't come from only its rainforests. Just under half of the region is forested. The rest is either alpine rock and ice or muskeg, a term that encompasses the ecosystems scientists define as bogs (moss-dominated wetlands) and fens (sedge-dominated wetlands).

Walking through these soggy margins isn't really walking at all. For most people, it's a cautious prance, each step a silent prayer that you don't sink so deep your boots fill with water. Michael Kampnich is the only person I've met who strides through muskeg as confidently as if he's walking on a trail. He's been here enough times to know where it's safe to step, and where the edge of a centuries-old beaver dam offers the only sure footing around.

Kampnich first came to Prince of Wales in the 1980s to work as a timber faller, which he loved until he got married and had two daughters. After that, logging felt like too dangerous an occupation, so he quit. He worked as a police officer and a harbor master, then—beginning to suspect that the environmentalists writing letters to the local paper about the value of old-growth forest were onto something—he joined the Nature Conservancy to try to protect the remaining old growth on Prince of Wales. Now he's mostly retired, and one of his greatest joys is setting up motion-triggered cameras around the island and catching glimpses of the lives of animals living among the mist.

The day Kampnich and I planned to check his camera traps, a gale-force storm settled over Southeast Alaska, so we were joined by Matt Jackson, who had been piloting a boat from Sitka to Ketchikan but was weathered in on Prince of Wales. Like Kampnich's, Jackson's roots are tangled with the logging industry. His father at one time built logging roads for the Forest Service. After the logging industry began to decline in the late 1990s, the family was forced to move "down south" to Missouri. Rather than blame environmentalists, Jackson directed his anger at the boom-and-bust extraction economy. He now works as a climate organizer with the Southeast Alaska Conservation Council, advocating for policies that could help local communities transition from old-growth logging to more sustainable industries like fishing and recreation.

As Jackson and I followed Kampnich through the muskeg, tendrils of clouds fell down the mountainsides like strands of loose hair. Evergreens raked their branches through them. Occasionally, the clouds settled over us and unleashed torrents of rain. No one remarked on the weather.

At a seemingly random spot in a seemingly random expanse of muskeg, Kampnich paused and bent down. When he straightened, there was a handmade cedar ladder in his hand. He leaned it against a nearby spruce tree, climbed up about four feet, and unstrapped a camouflaged camera the size of a cellphone. Then he plugged the camera's memory card into an iPad. Jackson and I peered over his shoulder as videos played on the screen: a black bear cavorting in a pool a few feet behind where we stood; a wolf striding purposefully past. "This is a major crossing trail," he said. "Deer, bears, wolves, otters—everything goes across here."

Habitat that's good for wildlife also tends to be good for the climate. As DellaSala had told me, "There's a nice overlap. If you protect the biodiversity, you also protect the carbon, and vice versa."

Like many of the region's forests, the muskeg of Southeast Alaska has grown relatively undisturbed since the end of the last ice age. The sphagnum moss that dominates muskeg acts as a sponge, soaking up water and carbon and creating an acidic, anaerobic environment that dramatically slows organic matter's decomposition. As a result, the muskeg can be up to 20 feet deep, made from the accumulation of a millennia's worth of dead moss, grass, branches, and shrubs. "We're standing on top of a solid brick of carbon," Jackson said. He picked a blueberry and popped it in his mouth. "Literal tons of carbon."

Although scientists are just beginning to study the role of muskeg in carbon sequestration, muskeg and other peatlands around the world may hold up to twice as much carbon as forests. In fact, the Tongass's ability to sequester carbon is inextricable from muskeg's, since muskeg soaks up carbon from surface water in the forest that would otherwise flow into streams. Given that muskeg constitutes nearly 2 million acres of Southeast Alaska, Jackson believes that the Tongass's contribution to global carbon sequestration may be undervalued. If we counted muskeg, the Tongass could be keeping significantly more carbon out of the atmosphere than is currently estimated.

ONE THING YOU LEARN in the Tongass: No matter how long a storm lasts, the sun will eventually break through. One of my final days on Prince of Wales was gloriously sunny, and I postponed a meeting to go kayaking. I drove to a place where a rushing freshwater stream dissolved into a saltwater bay, and beneath a cacophony of gulls, I pushed offshore one last time.

Paddling the length of the bay was like paddling in a dream. I passed million-dollar lodges and modest trailers, fringes of old growth and the scars of clearcuts, and more lion's mane jellyfish and harbor seals and bald eagles than I could count. I stopped at a random point and found paths worn into the earth by wolves' paws. I paddled farther, toward hazy island-mountains rising in the distance. Finally, dazzled by the sun on the water, I scraped ashore at a barnacle-crusted beach and wandered toward a wall of alders.

I don't know what I expected as I pushed through their tangled branches, but suddenly, there it was: the feeling I remembered from years before, the sense that I was no longer in a forest but in a room, an expansive, sheltered, living room whose ceiling was a dome of cedar and spruce boughs and whose floor was laced with ferns and mushrooms. When I guided in the Tongass, one of my favorite experiences had been sleeping under a tarp in exactly such a place, my nose inches from the ground. On this autumn day, I lay down again and rested my cheek against the forest floor, breathing in the rich scents of humus and moss and evergreen needles.

Much of the magic of old-growth forest unfurls beneath the surface. Ferns are linked by a perennial underground rhizome, connecting individual plants into a giant organism that rivals some trees in size. Mushrooms' hidden mycelia may live for hundreds of years, creeping through the dark soil in search of death to keep the forest alive. And tree roots reach toward one another through a network of fungal filaments miles long that form a complex underground web. Trees use this web to share carbon, nitrogen, water, and other resources and to send chemical signals warning of aboveground threats like insect infestations. The biggest, oldest trees—the ones ecologist Suzanne Simard calls Mother Trees—are the most generous, giving energy and nutrients to younger trees to help them thrive. Sometimes, an ailing tree even offloads the bulk of its carbon to younger trees before it dies, sending a burst of life that ensures the forest will live on.

Like the trees and ferns and mushrooms connected beneath the soil, like the salmon connected to the trees and the trees connected to the deer and the deer connected to the people, all of our fates are woven together. The abundance of the Tongass doesn't only benefit the people and animals in its immediate vicinity. It benefits all people and wildlife—all of us who would struggle to survive if the climate were to rise by a few degrees more. In its generosity, the Tongass gives to even those of us thousands of miles away.

The Tongass alone will not save us from our voracious consumerism or addiction to oil. But it can give us time to figure things out. It can absorb excess carbon dioxide while we develop and adopt a lifestyle that's less dependent on fossil fuels. It can keep heat waves and hurricanes and rising seas somewhat at bay. It can give us snowfall and clean air and vibrant corals. And for those of us lucky enough to see it in person, the forest can give us awe.

This article appeared in the Summer 2022 quarterly edition with the headline "The Giving Trees."