Nestled in the mountains of eastern Australia are fragments of an ancient world. Damp, dark and lush, they are some of the oldest ecosystems on Earth: temperate rainforests that have persisted since the days of supercontinents and dinosaurs.
The Gondwana Rainforests of Australia — and the hundreds of rare species that call them home — are the ultimate survivors, clinging to wet, wild patches of a continent that's increasingly developed and dry.
But even these forests could not escape the country's unprecedented fire season unscathed.
Standing barefoot in a shallow stream in Australia's New England National Park, ecologist Mark Graham reaches down and grabs a charred piece of wood that's washed up on a rocky bank. Rain falls from a blue sky through a gap in the dense canopy overhead.
"These are the deepest, wettest parts of the whole landscape, pure rainforest," he says. "To see them burning... it was like this dissolution of the biosphere. It was like, 'this is not supposed to happen.'"
Upstream, one side of the rainforest is as it should be: a dense, tangle of green ferns, shrubs and trees. The other is brown and black, an understory scorched.
For Graham, who trains people about wildfire for the Nature Conservation Council, an Australian environmental group, it's a signal of how much things have changed. Fires are burning with greater intensity and more frequently in places that are used to it, and expanding into places that are not. Australia's rainforests are just the most recent, sobering example.
More than half of the Gondwana rainforests, a World Heritage site, burned during the 2019-2020 fire season.
"These are consistent patterns across whole biomes of the planet now," Graham says. "We're in the Pyrocene, the age of fire."
Human development "a vehicle" for expanding fire
Australia's season followed years of increasingly deadly and large fires around the world. Flames scorched more than a fifth of the country's forests, a globally unprecedented amount. That came amidst the hottest and driest summer on record. Researchers say human-caused climate change contributed to those conditions, making the fires more likely.
Globally though, the amount of land being burned in wildfires has actually declined over the last few decades. Despite the influence of climate change, human land-use, largely the increase of agriculture, has led to great reductions in the amount of savanna and grasslands that burn.
The same is not true for the world's rainforests. There, human land-use and climate change are working in disharmonious concert to intensify wildfire spread.
Some of those fires may have started naturally, but the vast majority were intentionally started by humans trying to eke out a living off the land. Those fires were then able to keep burning because humans had changed the conditions on the ground.
Large swaths of old unbroken rainforest are not very susceptible to wildfire, "except in perhaps tens of thousands of year cycles," says Robert Kooyman, a botanist at Macquarie University who's worked in the Amazon and Australia's rainforests.
But when humans break the continuity of the forest, fire finds footholds in the fractures left behind.
"The expansion of the road network, the settlement that follows it, the clearing, the logging — the whole disturbance matrix becomes a vehicle for expanding likelihood of fire," he says.
And when a fire burns in the rainforest, torching canopy and introducing more sunlight, it can change the type of vegetation that grows back, increasing the likelihood of future fire.
Ecologists warn similar patterns are happening in Southeast Asia and Central Africa, the latter of which is home the world's second-largest tropical rainforest, the Congo Basin Forest.
"There's little to room escape the fact that scale of fires, the extent of fires and the places that fires are burning, globally, has expanded," Kooyman says.
A feedback loop between fires and climate change
An expansion in the global range of wildfire is troubling for a number of reasons.
For one, "we all share the same atmosphere," says Dr. Nancy Fresco, a research professor at the University of Alaska Fairbanks.
Wildfires emit carbon dioxide into that shared atmosphere, and carbon dioxide is a major contributor to climate change. That means fires have the ability to accelerate climate change the same way climate change has the ability to accelerate fires.
Scientists worry that kind of feedback loop, set off by man-made emissions of greenhouse gases, could lead to runaway climate change, where climate-fueled fires cause even more fires.
The problem is amplified in the Arctic, where Fresco works, because the tundra is home to vast amounts of stored carbon that's locked away in the form of permafrost and peat. Colder temperatures slow the rate of decomposition, letting vegetation build up over thousands of years. Usually that carbon is frozen in place. Fires can unlock it though, by burning away the insulating layer of vegetation on the surface. And once that carbon is released, there's no getting it back.
The Arctic is warming twice as fast as the rest of the planet, making more and more of the tundra susceptible to more frequent fire.
Last year, massive wildfires raged across Siberia, Canada and Alaska.
Those fires and a warming climate are changing the makeup of the Arctic, Fresco says. Vegetation is changing. Older conifers, adapted to fire, are being overtaken by younger deciduous trees. That has ramifications for the broader ecosystem and the species that depend on the status quo.
Prehistoric time capsules
Change is part of the natural world. Ecosystems shift. Continents drift. Disruptions like fire happen.
Ecologists like Graham are keenly aware of that.
Standing with his hand on the gnarled trunk of a massive Antarctic Beech, a relic of Australia's Gondwanan past, he points out different eucalypt species that are growing in the surrounding area. This is the edge of a section of Antarctic Beech rainforest, fire-adapted eucalyptus trees mix with fire-vulnerable shrubs.
All are burned.
"If this were an isolated incident, a single event, I could accept that as a stochastic event, something that through time occurs when factors line up," Graham says. "But these factors have lined up on a landscape scale. That is deeply, deeply disturbing."
The vast majority of Australia's forests are adapted to fire and ecologists are confident that, given enough time, many of them will recover.
It's less clear if the burned portions of rainforest will follow suit. Because fire so rarely burns in these areas, it's hard to know how they'll react.
One thing is certain, though. There are only small portions of Gondwana rainforest left on the planet. They are refuge to plant and animal species that have existed for millions of years. And during Australia's recent fire season, those refuges shrank, further stressing these time capsules into our prehistoric past.
"At this type of pace, [for many species] there won't be anywhere left to go," Graham says. "The pace of change is simply too great."
DAVID GREENE, HOST:
We are about to visit some of the oldest ecosystems on Earth. We're going to rainforests in Australia that have survived since the days of dinosaurs. During the country's recent fire season, though - it was the most devastating on record - parts of those forests burned. NPR's Nathan Rott looks at how this happened and what it means.
NATHAN ROTT, BYLINE: It's a short, bouncy drive across a boggy field to get to the forest's edge.
MARK GRAHAM: Hang on.
ROTT: Ecologist Mark Graham is behind the wheel and will be guiding us through a recently burnt part of the dense tangle of green that lies ahead.
GRAHAM: We walk from here.
GRAHAM: It's a bit sloppy just here...
ROTT: Graham is with the Nature Conservation Council of New South Wales, an Australian environmental group. In his day job, he trains locals how to better manage wildfire. This past summer, though, there was no managing that.
GRAHAM: I'm still alarmed by what went on here. Like, there were desperate measures required to pull fires up. And most fires were not pulled up.
ROTT: By pulled up, he means contained. Desperate measures were taken to stop fires and didn't always work.
GRAHAM: And you can see it burned very severely in front of us.
ROTT: He stops to point to the section of forest that is remarkably colorless compared to the lush green around it.
GRAHAM: Everything in the understory and in the shrub layer is dead. And that was all rainforest
ROTT: Subtropical temperate rainforest, to be more precise, similar to the type that used to blanket the super continent of Gondwana before Australia broke from Antarctica and started its slow drift north. Tens of millions of years later, here in the cooler mountains of east Australia, a few small patches of that ancient rainforest are hanging on.
GRAHAM: So there's...
ROTT: Oh, speaking of hanging on.
GRAHAM: There's a chain that takes us down here. So it's not super dangerous, it's just...
ROTT: To show us how unusual this fire was, Graham says, we need to get to the bottom of a steep ravine.
GRAHAM: Like, this little footholds and handholds. But this is - yeah. The chain can help on this last bit.
ROTT: Holding your mic in your teeth.
With the chain for help, we descend towards a rushing stream over mossy logs and past dew-speckled ferns.
GRAHAM: Yeah, just got to squeeze your way through there a bit.
ROTT: The air is so humid at the bottom, there's a light mist.
GRAHAM: These are the deepest, wettest parts of the whole landscape.
ROTT: But fire even made it to here. Upstream, we see mossy logs, wet to the touch, that are half-charred.
GRAHAM: You know, I've been here all my life and there's lot of other people who have. We're all just scratching our heads going, this is not right.
ROTT: Ecologists and other observers in East Australia and other parts of the world are saying the same thing. It's not that fire doesn't happen in rainforest, it does - just very rarely without human help. What's shocking is that rainforest wasn't just burning in that little patch we just visited. It was burning up and down the Australian continent. In New South Wales, more than half of the area designated as Gondwana Rainforest of Australia burnt in the last fire season - 54%.
KARYN TABOR: What's happening is we are seeing climate change at work.
ROTT: Karyn Tabor is with Conservation International, where she tracks wildfire and ecosystem changes globally using satellite data.
TABOR: Hotter weather, drier weather conditions and longer fire seasons - this is causing more fires.
ROTT: And it's making those fires harder to manage. A synthesis of some of the world's best fire science that was done in response to Australia's fire season found that, yes, human-caused climate change is increasing the global risk of wildfire. Fire season has lengthened across a quarter of the burnable earth. Fire weather conditions are happening more frequently in places like Australia and even on the opposite end of the world, the Arctic. Nancy Fresco is a research professor at the University of Alaska Fairbanks.
NANCY FRESCO: The change is happening in a couple of ways. In the areas that typically burned, we're seeing hotter fire, more frequent, more intense. And then we're also seeing fires extending into areas where they didn't burn typically.
ROTT: In the Arctic, fires are burning further and further north. In the Amazon, Central Africa and Southeast Asia, more rainforest is burning, partly because of climate change, but also because of another human element. Here's Dr. Robert Kooyman, a botanist with Macquarie University.
ROBERT KOOYMAN: Of course, there's also the fact that we are now 9 billion people. And the massive modification to landscapes in terms of forestry activity, land clearing, land modification - all of those things have occurred at the same time.
ROTT: And all of those disturbances, Kooyman says, provide footholds for fires to take off. So why should we care that more places are burning? Again, Nancy Fresco.
FRESCO: The first answer is, well, we all share the same atmosphere.
ROTT: And fires release carbon into that atmosphere, carbon that then feeds global warming, warming that then feeds fires, fires that then release - you get the idea. Climate scientists call this a positive feedback loop, though, there is little positive about it. Because these ecosystems are not used to fire, they'll have a hard time recovering, leaving carbon in the atmosphere and further threatening already threatened species. The Gondwana Rainforest of Australia are like these little time capsules into a prehistoric past. And visiting various parts that burnt, the difference is jarring. Burnt areas look different. They're brown, versus green. They feel different because they have less shade. And they sound different. Unburnt...
(SOUNDBITE OF ANIMALS COOING)
(SOUNDBITE OF BIRDS TWEETING)
GRAHAM: Yeah. It's a completely different physical system.
ROTT: Back with ecologist Mark Graham, we're walking down a recently burnt hill sprinkled with Antarctic Beech, these ancient trees with massive canopies and gnarled trunks. They're a hallmark of Gondwana rainforests.
GRAHAM: They are the ultimate survivors.
ROTT: But Graham says what's so worrying to him is that many of these ecosystems, and the endemic species that depend on them, have already been reduced to near nothing. Logging and other human activities have already pushed them to the brink. Wildfire is just another threat.
For a lot of the critters, it's like being on a shrinking island.
GRAHAM: That's a really, really good description. And ultimately, they've - at this type of pace, there won't be anywhere left to go. The pace of change is simply too great.
ROTT: Too great even for ecosystems that have survived for millions of years.
Nathan Rott, NPR News, Bellingen, Australia.
(SOUNDBITE OF TRISTAN DE LIEGE'S "PAPILLON") Transcript provided by NPR, Copyright NPR.