How fungi are surviving—and even thriving—in a warming world

On a mid-August Sunday in that bleak pandemic summer of 2020, the air near central California’s Big Basin Redwoods State Park felt muggy, almost tropical. Weird, thought naturalist Christian Schwarz, who had spent a good decade venturing among the park’s old-growth redwoods in pursuit of mushrooms. He was expanding his mental taxonomy of the fungi he’d become obsessed with when he was fourteen, following his brother’s curiosity, who followed Frodo Baggins’s. Big Basin was a place to walk among giants in the mossy green, footsteps muffled in the duff of the forest floor. A place normally assured to be wet even in peak summer, all those ancient trees, living and dead, drawing moisture from sky and soil.

But that California summer was parched. The waters down in Baja were so warm, they spawned a storm massive enough to carry its strength a thousand miles to the north, where its moist, unstable air collided with the dryness in Big Basin on that Sunday. Hundreds of lightning strikes flashed across the sky in the span of a couple hours. Sparks flew. The storm illuminated a world already off-kilter, social lives ruptured by the pandemic and George Floyd dead and everyone seeming equal parts angry and frightened.

Santa Cruz doesn’t get lightning, Christian thought, as the sky strobed and heavens rumbled. The prior year, he’d reluctantly returned to the University of California, Santa Cruz to finish the undergraduate degree he’d abandoned years earlier when he realized he was much more interested in the mushrooms growing outside of his classroom window than the lecture happening within. A California native, he was thirty years old and knew thousands of species of mushroom by sight and smell and feel. He was ready to apply his self-taught knowledge to a more systematic study of fungi, turning his Big Basin meanders into a set route of study plots. But he still thought of it as visiting old friends he knew intimately. I know you, and you, and you, he said to the witch’s hats, the poor man’s licorice.

That summer wasn’t good for mushrooms. The heat had desiccated even the ancient wet forests, pummeling them to punk, and when lightning reached her fingers from thundercloud to treetop, the fires began. Conflagrations erupted across California. Christian worried about his fungi survey plots in the park. If there were summer fruitings of prince mushrooms, they cooked. The flames of what became the CZU Lightning Complex Fire reached from the forest floor to its three-hundred-foot crown. A quarter of Santa Cruz County burned. So did 97 percent of Big Basin’s forest.

A couple months later, officials let Christian return to his study plots, long before it was safe for the rest of the public to enter. Alone, he moved through a blackened forest where fires still smoldered, flickering into flame when the wind blew just right. He clambered across the burned-out bulk of a bridge to cross a creek, thinking, My place is gone. It felt like a graphic novel, scenes made simple in strokes of black, white, green, blue. The soft duff had been transformed to ash, two feet thick in some areas, and he struggled with disorientation. Landmarks had literally been erased, leaving smudges in the map of his mind. He was bereft.

And then, his curiosity took over. No one had ever seen an old-growth redwood forest burn so completely. What had started as a baseline mushroom study of Big Basin was now an exploration of what a warming world does to fungi biodiversity. Redwoods were soon sprouting green shoots from completely carbonized trunks, and fungi were fruiting everywhere. What ecological arc, he thought, might I witness?

A wash of honey mushrooms along the edge of a creek released so many spores, they blanketed the water white. And then, he was stopped in his tracks by a multitude of strangers. Tens of thousands of mushrooms he had never seen before. An abundance of the unknown. His heart quickened, and he felt mildly panicked. Bewildered. Overjoyed. The beloved had done something mysterious and beguiling.

Who are you? he asked, leaning in to look. He knew it was some sort of Hygrocybe, known as waxy caps, but unique among any he’d ever seen. He inspected the abundant clusters, which reached up with tall, ghostly white stalks and mocha-colored caps. He held one close to his nose and smelled little but felt the fragility of the mushroom’s body in his hand. Like holding water. His love of fungi deepened.

The mushrooms were clearly responding to the fire. He gathered a sample, and DNA testing revealed that the closest match was another waxy cap discovered after a wildfire in the Great Smoky Mountains on the other side of the country. He’s taken to calling the species “exuberant cindercap.”

Christian told me this story five years later in Eugene, Oregon, as the two of us sat before a large plate glass window in Sweet Life Patisserie. His body was compact, bundled up in a fleece-lined denim jacket, and he had a week’s worth of stubble on his face. His hands cradled a coffee cup. Now thirty-five years old, he teaches at UC Santa Cruz, the same school he dropped out of and returned to.

If his happy place for fungi is central California, mine is in western Oregon, a place I once called home and thought I’d never leave. But I did leave. I went back last fall, wanting to understand the same thing Christian did: what a changing climate means for mushrooms. What might we learn from the exuberant cindercap and all of their kin? How does one lie dormant for an eternity and then thrive amid what appears, to some, as disaster? Because it seemed to me that disaster was unfolding all around. Climate catastrophes were increasing exponentially, and American rancor was at an epic level, and an election was right around the bend. How could I use fungi, and all that we know—and don’t know—about them, as a lens through which I might find greater understanding? What lessons might they offer us about when to hide and when to burst forth? About how to recognize the tethers we have with the world around us and to nurture them so we might all grow stronger?

What might fungi have to say about waiting for devastation—transformation—to come and then knowing that the only response is to launch your body skyward, make more of yourselves, gather every friend and family member you can find and rise together? To be exuberant, even as the winds rekindle the fires burning in every direction, sparks flying.

It’d been twenty years since I left my home in the foothills of the Cascade Mountains to leap to the other side of the country, from a barn on twenty acres to an illegal studio sublet in the East Village. Longer since I took a mushroom identification class with my dear friends Joe and Cathy, who put me up in their guest room for this visit. The Oregon landscape, still so familiar, has been transforming in my absence. Back then, wildfire season was nearly nonexistent, and summer skies turned a blissful blue as the rains abated. Now, I heard reports of friends locked up in their houses in July, wildfire smoke choking the air. Then, rains dependably arrived in early October, and we filled five-gallon buckets with chanterelles. In the spring we pursued morels. I remember how I was unable to find them until the moment I finally saw one, its crenellated form crystalizing against the dark ground, and the image locked into my brain like a lost puzzle piece. I looked up and saw hundreds all around me. Now, Joe warned me on the phone before my visit that the rains hadn’t come, and few mushrooms were to be found.

Oregon is where I learned to understand the natural world and my place in it; where I fell tumbling in love with all it was capable of. Climate change seemed to be hacking away at each thread of Earth’s tapestry, and my memories of those years along with them. But fungi have a way of weaving themselves throughout the entire creation. Could they help me stitch my understanding back together?

When it comes to perceiving the extent of the fungal kingdom, our senses are wholly inadequate. Most fungi that humans tend to notice are the ephemeral sexual fruiting bodies we hunger for—for food, for medicine, for beauty, for blowing our minds. Homo sapiens’ sense of smell atrophied long ago; if we even want to find underground truffles, we need dogs and pigs. In the limited and delineated ways of human thinking—“animal, plant, or mineral?”—fungi defy categorization as we usually conceive of it. Long lumped in with plants, fungi were only recognized as their own kingdom in 1969.

They are neither plant nor animal, but a wild conglomeration of things, existing in ways that are so central to ecosystems that what we have learned about them forces the breakdown of traditional taxonomy. Large-scale DNA-sequencing datasets are expanding daily, but identifying a double helix doesn’t tell you how an organism exists in relationship with everything around it. And even with what we have learned, scientists from the Royal Botanic Gardens at Kew estimate that as many as 95 percent of the planet’s fungal species have not yet been identified.

For the species we do know about, the vast majority are mycorrhizal, living in close relationship with a photosynthetic partner, exchanging resources so both can survive and thrive. Plants give their carbon-laced sugars to the fungi, and the fungi exponentially increase the plant’s uptake of nutrients and water in exchange. This partnership allows plants to better tolerate stresses, from droughts to pests to pathogens, and helps trees like Douglas firs and redwoods reach their towering heights. Author Merlin Sheldrake describes mycelium, which makes up the mycorrhizal network, as the “ecological connective tissue, the living seam by which much of the world is stitched into relation.”

Where exactly, I asked Christian at the bakery, were those creekside honey mushrooms and exuberant cindercaps lurking? Where do pyrophilous fungi—the fire-loving charcoal eyelash and the violet fairy cup and those morels I used to hunt for—secretly slumber? Especially in places where fire may have not happened for ages, like an old-growth redwood forest on the Pacific coast?

The fungus could have been embedded deep within plant tissues, he said, but he suspected they were mycelial, living contentedly in nonfruiting form, thin white filaments of hyphae winding through soil. These mycorrhizal networks are said to be the way trees in a forest communicate, though it’s possible that the excitement about such “mother trees” could be a bit overblown, as a recent paper from Nature suggested. We’re still learning.

But what we do know is that their kingdom is a profuse one. Fungi encompass some of the largest and oldest beings on Earth; they can span miles across and live for thousands of years. Or they can be single-celled and live for only hours. And though we tend to associate fungi with wetness—the lead mushroom identification guide for the past three decades has been All That the Rain Promises and More—fungi can live in nearly every environment on Earth. They dwell on snowy mountaintops and at hydrothermal vents at the bottom of the ocean.

Maybe their expansive range is why we have such a hard time conceptualizing the kingdom of fungi: people, in spite of our penchant for finding reasons to fight, are boringly similar, demonstrating our differences in things like mere inches or percentage of melanin. Fungi instead are a diverse delight, an effusive sensuality of colors, shapes, smells, textures. Could this be the first lesson from them—to revel in abundance? To see something, someone, different than us and lean in, curious, instead of turning away?

My two-week visit was bookended by a pair of annual mushroom festivals, scheduled to align with what was supposed to be peak mushroom season. At the beginning of my trip was the Yachats Mushroom Festival on the coast, where I’d met Christian. At the end of my trip was the Mount Pisgah Mushroom Festival, held at an arboretum on Eugene’s edge, closer to where I’d once lived. Both festivals struggled with the reality that the rains hadn’t come, which meant fewer mushrooms. For weeks, the weather report forecasted rain, but each day of my visit the sky would blush blue or erupt with clouds full of potential only to evaporate, or tempt us with a recalcitrant gray that grudgingly spared a few drops. Though Oregon still shared her staggering beauty—burnished bigleaf maples and blackberries turning to umber, Canada geese skeining across the sky—my thoughts were dark.

I had arrived in Oregon with a pile of research papers in my backpack. One of them was entitled “Disaster Mycology.” Something about the phrase wouldn’t let me go, and I kept turning it over, like a stone in my pocket. It wasn’t all doom: “The stories of fungi include disasters,” the paper concluded, “but also stories of recovery.” Stories of recovery, too, seemed like part of the answer we needed from fungi at this moment.

No one offered me psychedelics while at the Yachats Mushroom Festival, but I was handed an eggnog spiked with whiskey infused with a sweet-tasting fungi known as candy cap mushroom—it was delicious. I also went on official and unofficial mushroom walks—“This place is fungally devoid!” exclaimed Joe at the dearth of mushrooms—and heard Christian Schwarz deliver the keynote talk as a crowd of hundreds nibbled on chanterelle pasta and puff pastries filled with spinach, artichoke, and chanterelles, also delicious.

When I asked people about the phrase “disaster mycology,” most hadn’t heard of it. Or they wanted to focus on the positive aspects of the fungi world. It was a festival, after all. It seems more popular to turn fungi into a kind of panacea. News articles keep popping up about researchers finding new ways to turn fungi into saviors to fix our broken world and bodies. Fungi to consume plastics. Fungi to replace plastics. Fungi to clean up oil spills. Psilocybins to fix undesirable thought patterns. Fungi inoculations to transform agricultural production. It is fungi that gave us penicillin and the drugs to allow organ transplant recipients to live. If we humans ingest them, they can nourish us, make us puke, or take us to the stars. Sometimes all at once. Can they fix everything?

Maybe that’s the wrong question.

As I read more, I was beginning to feel that the right question might be to ask them for a lesson on how to exist in the world in the first place. With water and air warming, considering the world from the vantage of fungi could be illuminating. They’ve had the ability to sustain and persevere for hundreds of millions of years, after all. I decided I needed to reach out to one of the authors of the disaster mycology paper, Johns Hopkins epidemiologist Arturo Casadevall. He, along with a colleague, had coined the term that was haunting me.

Arturo’s twinned interests in mycology and human health developed when he began finding fungi inside people’s skulls. Arturo, whose family had fled Cuba and started over in New York, was just beginning his career as an epidemiologist in the 1980s. AIDS was ravaging human bodies, with deaths caused not by the disease itself, but by opportunistic infections, including fungal infections, that would colonize vulnerable bodies. Arturo knew that fungi had historically inconvenienced humans—think athlete’s foot—but rarely killed us. That, he proposed in his book What If Fungi Win?, was changing.

Most fungi like it cool, preferring temperatures below 86 degrees Fahrenheit. Our bodies hover at 98.6 degrees Fahrenheit, making us coexist quite nicely, each of us nestled in our separate biological niches. Arturo argues that this is a part of the reason that mammals and fungi both flourished after the K-T event 65 million years ago that ended the age embodied by dinosaurs.

That peaceful coexistence could be ending. Arturo believes that the AIDS patients who succumbed to infections hint that fungi could be adapting to our warming world while human body temperatures seem to be dropping, closing the gap that divides us. This could lead to outcomes like untreatable fungal infections, or entirely new ones. Between 2012 and 2015, people in Venezuela, South Africa, and on the Indian subcontinent all became gravely ill with what turned out to be Candida auris infections. A few years earlier, no one had even heard of the species.

“We don’t know what’s out there,” Arturo told me, over Zoom. “How can humanity prepare?” This is the unfortunate flip side of the age of fungal discovery we find ourselves in. So much is still unknown, and some of that ignorance could devastate us.

If the AIDS epidemic was the disaster of the ’80s, then climate change is the one of our current era. I asked Arturo about its effects on fungi.

“It’s hurting what’s there,” he told me, but they are also “very rapidly adapting.” He didn’t hesitate when saying, “Fungi will survive.”

What qualifies as a catastrophe depends on your point of view. Cataclysm can shatter an environment, spawning a wave of adaptation, altering ecological and biological relationships among creatures from microbes to megafauna, which in turn can transform the entire ecosystem. The response can be exuberance or extinction. Sometimes fungi are winning while we lose, like when dormant spores sprang to life under the dancing feet of California music festivalgoers last summer, giving fourteen people the fungal infection Valley fever, or when black molds blossom across bedroom walls after climate-fueled hurricanes. Fungi can also be saviors that help restore ecosystems, like when gophers were introduced onto the annihilated Mount St. Helens after the volcanic eruption so they could dig up the soil, inoculating the surface with the fungal life they unearthed. The reality is that fungi’s impact on human life in a warming world could tilt in either direction. More likely, it will be both good and bad at once. Yes . . . and. I have marveled at humans’ ability to adapt but have begun to wonder if we’re reaching our limits. Fungi will exist in the future. Will we?

My conversation with Arturo would happen after I returned home, but on the last weekend of my Oregon trip, I buckled into Joe’s gray Toyota Tacoma truck as he drove us out to Mount Pisgah Arboretum. The next day, thousands of people would attend the mushroom festival that by some accounts is the largest on the West Coast, but on Saturday the atmosphere hummed with the steady stirrings of preparation. Volunteers from the Cascade Mycological Society and students from Lane Community College busied themselves identifying and sorting mushrooms before laying them out beside labels on long tables in an airy pavilion.

I was sitting on a low wall just outside the pavilion’s entrance, talking with Ron Hamill, who Joe had introduced me to. There are some big names in the mushroom world, legendary figures with legendary tales, like the man in the dapper hat made of mushroom material who told me a long story about eating copious amounts of psychedelics. Ron was different, and I was drawn to his introspective presence. He’d taken a break from his role as an expert identifier to sit with me. He wore a plain baseball cap the color of the sunless sky, browline glasses, and a smile that spread across his clean-shaven cheeks like ripples on a lake. Ron is a botanist and mycologist who, for thirty years, has contracted with government agencies to survey public lands for fungi, as well as lichens and liverworts and vascular plants. He loves that he is paid to tromp through woods that span from California to the border of Canada. He does not love that he has seen these lands, and the fungi they contain, transform in his lifetime.

When I asked him about fungi and climate impacts, his answer was unequivocal.

“It’s not good,” he said. “They’re crashing.”

When conditions are good, everything is expanding underground, Ron told me. Roots are extending, fungal species connecting.

“A single tree can have as many as three hundred to five hundred species attached to it,” he said, his voice filled with wonder.

When conditions are bad, the system retracts. With no spare resources to share, everyone in the neighborhood becomes stingy, snapping their drapes shut. Trees become more vulnerable to droughts and insects. When reports come out about trees dying, the diminished fungi are the story between the lines.

He recalled the heat dome of June 2021, which buckled roads and killed hundreds of people. Even before the fires came, heat vaporized moisture from the land. Ron was surveying in northeast Washington state, where the temperature reached 117 degrees. He saw deer stagger by with their tongues hanging out. Watched young saplings wither in the span of days. The heat dome acted as a thief, water its heist. It stole from the watering holes and the creeks, becoming yet another stressor to landscapes already fragmented by logging and development. It even filched from the downed trees that serve as remnant refugia—places usually protected from disaster where fungi and other species can wait out bad times. Where Ron’s hand should have grasped a wet sponge within those downed logs, there was only dryness.

Ron believes the heat dome changed the region forever. Christian witnessed fungi after the flames, but Ron is noticing pyrophilous mushrooms fruit before fires, as though they can feel them coming. When he sees tooth fungi, like Bankeraceae, flush brightly for a few years and then vanish, it feels like a last hurrah to him. In other places, he’s seen conifer forests unable to recover after fires, fields of asters or cheatgrass replacing ferns that once were. Stifling summers like these definitely changed Ron’s life. A year before the 2021 heat dome was another scorching summer that parched the region. A Labor Day windstorm caused powerlines to spark, setting off a fire that exploded in southern Oregon. The Archie Creek Fire burned 130,000 acres and 170 properties, including Ron’s.

As we spoke, the wind gusted, threatening to upturn the booths being erected to house a cider press and nonprofit organizations and books about mushrooms. Someone passed by and pointed out that we were sitting under an old dead tree. The forestry term for such a specimen is a widow-maker. We settled elsewhere in some unused chairs.

Ron’s obsession with fungi had begun as a love of taxonomy, but a decade ago he started to truly see the links within the ecosystems he surveys.

“It’s amazing,” he said. “It’s almost like the Buddhist concept of—boom!—it happens. Everything’s breathing out there, and it’s all very much connected.” The air, the water, the soil, the plants living and dead. The fungi.

“I love it,” he told me, then told me again. A love so deep it must be spoken twice. “It’s what makes my life worth being here.” He smiled.

“Mushrooms are really popular right now,” he continued, “but very little attention is being paid to the ecological aspects. It’s all about let’s go eat the rest of the world. I’m sorry, but that’s what it really is.” Geotagging and Instagram have indeed fueled an interest in mushroom hunting. I think of the seven-hour matsutake hunt I went on with Joe and others a few days earlier. Maybe more land gets picked over, but also, there is the act of being in the woods with friends old and new that forms community, connecting people and the land. What gratification I experienced in learning how to find the emerging buds, in slicing them into my ramen that evening. I felt the same connection I’ve felt every time I’ve foraged my food. But could that intense focus, noses to the ground, mean we were missing a much greater picture?

“Things change,” Ron was saying. “They always do. But this is something that didn’t have to happen.” His smile was finally gone. “It’s not a natural transformation, and I think we’re going to end up with a big void for a long time.”

I maintained my professional reporter’s gaze but wanted to embrace him, so we could sob together at the loss underway. I looked down at my notebook instead.

Twenty-four hours later, the gaping void felt distant, disasters absent from the joyful festival where I bumped into old friends—I know you, and you . . . Crowds danced to live music and bought mushroom earrings and learned about the good work of small nonprofits. They stood in a long line that wound through the pavilion to gaze at a magnificent array of 411 different species of mushrooms, a testament to the volunteers who searched far and wide to find them in the dry season. They circled through a tent to learn how to differentiate the edibles from the poisonous, sipping fresh apple cider. And in the center of the festivities many of the volunteers took a moment to unveil a memorial bench to Freeman Rowe, a beloved biology professor who had sparked the love of fungi for so many in the region, a human form of inoculation, like mycelial threads were fruiting in the next generation.

Then, the rains. Finally, in the last hours of the gathering, they fell. A child with rubber boots jumped in the center of a giant puddle, sending out waves.

As I leave my old home ground, I’m thinking Arturo Casadevall might be right. Even if fungi are crashing in places, they will survive. They might even win. They are patience embodied in a mycelial thread, a microscopic spore, a cell tucked into the depths of a leaf, soldered to a fissure in the seafloor. As we humans find inane reasons to divide ourselves again and again, fungi stay connected, to one another and the world they inhabit, sending out threads to stitch a living seam that holds everything together. They find strength in their diversity. When I’m saturated with dire academic papers, I turn to fiction. In the opening scene of Catalan writer Irene Solà’s gorgeous novel When I Sing, Mountains Dance, a man has just foraged an armful of black chanterelles and is freeing his cow, caught in a fence, when a storm suddenly approaches. The chapter is written from the vantage of the storm, which looses a lightning bolt that strikes the man dead, scatters the mushrooms, and sets off the story. Later, Solà returns to the scene, but now from the vantage of the fungi. “We remember the forest. Our forest. We remember the light. Our light,” the black chanterelles say in a singular voice. “Because we have been here always and will be here always. Because there’s no beginning and no end. Because the stem of one is the stem of us all. The cap of one is the cap of us all.”

The message from mushrooms is not a straightforward one, nor are they here to fix everything for us. That’s our work. To be human today is to be both threat and threatened. Parasite and host. Competitor and companion. Divided and one. Disaster might be upon us, but we could be, together, the thousands of exuberant cindercaps emerging amid the still-smoking redwoods. Joining our multitudinous forces so that we, too, might have neither beginning nor end. The choice is ours.