On Aug. 15, a small wildfire was detected in the hills above West Kelowna, in British Columbia. The landscape was parched and the wind was fierce, and over the next few days the modest blaze exploded into a raging conflagration. It raced down into the valley and toward Okanagan Lake. Wind blew red-hot embers across the water, sparking new fires around the city of Kelowna.
“I didn’t sleep much the night that the West Kelowna fires crossed the lake,” said Karen Hodges, who lives in Kelowna. “I could see the fires from my window. And so I was thinking about people I know in the valley and where their houses were.”
Hodges, a conservation ecologist at the University of British Columbia Okanagan, also found herself worried about wildlife. She had been studying some Western screech owls that had been nesting in the heart of the fast-moving inferno. “That speed of fire would be difficult for animals to evacuate in front of,” she said. Had the owls escaped in time? And after Canada’s worst wildfire season on record, what would be left for the survivors?
Fire is a natural phenomenon; some species actually benefit from its effects and even those that don’t can be remarkably resilient in the face of flames. But as fires intensify, they are beginning to outstrip nature’s ability to bounce back. “Not all fires have the same impact,” said Morgan Tingley, an ecologist at UCLA. “These megafires are not good for ecosystems.”
Megafires, which dwarf typical wildfires in size, have an immediate ecological toll, killing individual plants and animals that might have survived more contained blazes. In the longer term, changing fire patterns could drive some species out of existence, transform landscapes, and utterly remake ecosystems.
This incendiary age, which some scientists have called the Pyrocene, could lead to “a wholesale conversion of what habitats are where on the planet,” Hodges said. “Right now, everybody is talking about fires and smoke and who dies, because of the immediacy of this fire year. But really, truly, the long-term consequences are much more severe and sustained.”
Fire has been a planetary phenomenon for hundreds of millions of years, and plants and animals that evolved in fire-prone regions have adapted to periodic conflagrations. Some trees have roots that can re-sprout even if the trunk burns, while the mere smell of smoke will rouse some animals from torpor, a form of light hibernation.
But in many regions and ecosystems, fires are becoming larger and more severe. In the United States, wildfires burn far more land today than they did three decades ago, especially in Western states. Globally, the risk of catastrophic fires could increase by more than 50 percent by the end of the century, the United Nations reported.
Even fire-savvy organisms may find themselves outmatched. In northern Australia, frilled lizards can survive low-severity fires by hiding in the tree canopy. But during severe fires, when flames leap higher, lizards that employ this strategy may perish.
Fires are also spreading into ecosystems where flames are an unfamiliar threat. The megafires that erupted in Australia in 2019 and 2020 scorched the country’s rainforests, which contained many plants that cannot regenerate after burning.
Fires that consume more fuel may also produce more smoke per unit of area burned, threatening animals far from the flames. “All air-breathing animals are going to be impacted by smoke exposure, because the chemicals in smoke are toxic,” said Olivia Sanderfoot, an ecologist at UCLA.
Smoke inhalation can do more than cause respiratory problems. For months after severe peatland fires produced record air pollution in Indonesia in 2015, Bornean orangutans vocalized less frequently and their voices became harsher.
Animals that survive the inferno must then find food, water, and shelter on hot, dry, denuded landscapes where the risk of predation is high. (Surrounded by weakened prey, some predators thrive after fires.) Fortunately, fires tend to burn unevenly, ravaging some stands of trees while grazing or sparing others. These unburned islands can be a lifeline for fire-sensitive species such as caribou, which eat highly flammable lichen, as well as thin-barked fir trees. But some of today’s fires are leaving fewer of these oases.
“You could walk half a mile, and you wouldn’t see a single living tree,” said Andrew Stillman, an ecologist at the Cornell Lab of Ornithology. “Increasingly, these fires seem to create habitat conditions that are outside of the norms that these species are adapted to.”
That may be true even for fire-loving animals, such as the black-backed woodpecker. The birds nest in scorched trees and feed on the beetle larvae that colonize the charred trunks. But they prefer patches of burned trees that are near stands of leafy, living ones, which protect their fledglings from being picked off by predators, Stillman and Tingley found.
After the enormous Rim fire in California in 2013, scientists searched for the woodpeckers at nearly 500 sites across the expansive burn scar. They found just six birds.
Scorched, vegetation-less soil, which does not absorb rain well, can also hamper regeneration. Flash flooding after fires can wash ash and sediment into rivers and streams, polluting the water, killing fish, and reshaping waterways.
In the Northwest Territories of Canada, repeated fires have utterly transformed some forests. At one site, towering jack pines have given way to grasses and a smattering of “scrubby, stunted” aspens, which have light seeds that can be carried on the wind, said Ellen Whitman, a forest fire research scientist at Natural Resources Canada. “It is a very different place,” she added.
Change is not necessarily bad. Fires can prompt overdue regeneration in places where flames have been artificially suppressed, and forests are not inherently superior to other ecosystems. Old-growth grasslands, which are biodiversity hot spots, are also under threat; in some places, grasslands have turned into forests, partly because of fire suppression.
“So maybe in some ways, a bit of a balance is being restored,” Whitman said.
But it could take a long time for new grasslands to build up biodiversity, and landscape transformations have ripple effects.
Today, increased fire activity could push more than 1,000 threatened plant and animal species closer to extinction, scientists calculated. And many plants and animals are already facing multiple stressors. In Canada, Western screech owls are threatened by land clearing and the expansion of invasive barred owls.
The West Kelowna fire burned some of the owls’ nest trees, Hodges said, and the outlook is grim for a young, GPS-tagged bird that one of her students was tracking. “Its last known location was right in the middle of the fire that blew up so quickly,” she said. “And we haven’t detected the signal since.”
This article originally appeared in The New York Times.