Pyrocene: Fire Fundamentally Changing Global Forests
The phenomenal explosion of fires in Canada this year, which enveloped much of the most populous portion of the US in choking, toxic smoke got a lot of attention. Starting to hear the word “Pyrocene” – emergence of massive fire regimes which might be driving the larger climate system in unexpected, unpredictable ways.
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 evenif the trunk burns, while the mere smell of smoke will rouse some animals from torpor, a form of light hibernation.
Climate change is partly to blame, scientists said, but so are other factors, such as the expansion of highly flammable invasive grasses, which helped the deadly fires in Maui spread so quickly. More than a century of fire suppression has also left some forests thick with trees, giving flames more fuel. “When fires burn, they burn with so much intensity,” said Chris French, a deputy chief of the National Forest System in the United States.
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.
The animals in those ecosystems might be “fire naïve,” said Dale Nimmo, an ecologist at Charles Sturt University in Australia. “They may not have been under any natural selection to detect the subtle cues of fire in the air, or through sound. And so they may not recognize the threat as it approaches.”
The Algerian sand racer, a Mediterranean lizard, lives in a variety of habitats, only some of which experience frequent fires. In a 2021 study, researchers found that lizards collected from fire-prone sites reacted quickly to the smell of smoke, flicking their tongues and running around their terrariums. “In places where fire is not a common threat, lizards did nothing,” said Lola Álvarez-Ruiz, a biologist at the Desertification Research Center in Spain, who conducted the study.
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 the University of California, Los Angeles.
Manaus, the largest city in Brazil’s Amazonas state, has for days been engulfed by a toxic cloud of smoke from forest fires lit by what the government labeled “criminals”.
The city of nearly two million people has been forced to cancel some public events including a marathon.
The fires in the Amazon have produced a blanket of gray smoke over the capital of the northern state of Amazonas since Wednesday.
Air quality in the city is among the worst in the world, according to the World Air Quality Index.
“This smoke is hurting us. People don’t know what they are doing by burning the forest, and many animals are dying,” said Maria Luiza Reis, a 72-year-old Manaus resident.
“It’s sad, and it causes us difficulties. I wear a mask so I don’t breathe that toxic air because I already have health problems,” she added.
Health authorities have urged city inhabitants avoid exposure as much as possible.
There are “significant risks, mainly respiratory diseases” for those exposed to smoke, said Marcio Garcia, a director with the government’s public health emergencies department.
Amazonas, Brazil’s biggest state, has suffered the worst October in terms of fires in the last 25 years, according to data from the National Institute for Space Research (INPE).
INPE has registered 2,770 fire outbreaks so far this month as of Thursday, a 154 percent increase compared to the same period in 2022.
The government announced on Friday it was deploying two helicopters and an additional 149 firefighters to supplement an almost equal number already fighting the fires in the region.
Environment Minister Marina Silva blamed the fires on “criminals” who light them to clear the forest for farming.
“There is no natural fire in the Amazon,” Silva told a news conference on Friday.
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 like 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.”
According to (University of Colorado permafrost expert Dr Merritt)Turetsky, it won’t be until field researchers can explore affected areas that the fire season’s true costs in carbon emissions are more fully accounted for.
She is particularly concerned about the fate of carbon stored within the soils, including the layer of permanently frozen ground known as permafrost.
Some of the organic material on the ground and just under the surface contains carbon that was stored there as many as thousands of years ago.
“The atmosphere really is not expecting it back. So when we return old carbon to the atmosphere, that’s a true feedback to climate change,” she said.
Another ramification of so much fire in boreal forests is that the cool, wet peatlands that act as a buffer that maintains permafrost gets degraded, allowing for faster permafrost thaw and emissions of still more greenhouse gases.
What they’re saying: “The boreal forest is a carbon powerhouse in the global climate system,” said Turetsky, warning that it may be starting to lose this status.
If that happens, “It’s going to shift into some kind of other carbon function within the climate … And we don’t really know what that’s gonna look like.”
It’s foolish to care more about “doomerism” than to yell at people in power actively undermining efforts to address climate change.