Image: Michael Coe
Decades ago, the idea of firefighters in the Amazon Rainforest would have been absurd. But today, drought, increased human activity, and clear cutting have led to fires that destroy huge swaths of the forest each year. And most people, even those living near the Amazon, don’t even know it.
“Because it’s called the rainforest, people don’t understand that some places often go three to five months without rainfall,” Michael Coe, a researcher at Massachusetts’ Woods Hole Research Center who works in the Southeastern Brazilian Amazon, told me. “But, in fact, these fires, which are caused by humans, in conjunction with a drought year, can have a huge impact on forest mortality.”
Forest fires in the western United States often (understandably) get huge media attention—they’re huge blazes that can sometimes be seen for hundreds of miles. But forest fires in the Amazon burn closer to the ground, making them harder to see from a satellite.
“Generally they’re not these big, dramatic fires. They tend to be low and slow moving, but nonetheless, they kill the trees effectively,” Coe said. “We can usually look back the next dry season and see what happened with a satellite, but we don’t have all this big news coverage saying it’s happening. Usually we don’t learn about it until quite a while later.”
That’s because the Amazon is so large and remote that it’s difficult to even see the extent of a fire there, let alone fight one. Coe and his team spent eight years repeatedly burning small plots in the Amazon to see how the forest naturally fought back against fire. In rainy years, the fires were naturally put out fairly quickly. But in drought years, the fires continued to burn, sometimes until the dry season was over, which, in some cases, was months later. A study published by Coe in Proceedings of the National Academy of Sciences found that tree mortality could be more than 400 percent higher in drought years.
That’s because, beyond the direct impacts of putting water on a fire, a generally rainy season means there’s more humidity, so fires can sometimes be stopped without any rainfall at all.
Image: Michael Coe
NASA estimates that roughly three percent of the Amazon has been burned over the last 12 years. When that fire is contained in the middle of the rainforest, it’s not a huge deal. But when fires happen on the outskirts—as they almost always do, because humans are encroaching from the outside, it means the forest is likely to never recover.
“On the edges, they’re quickly replaced with pasture grasses, which are super flammable and then the problem becomes recurrent,” Coe said. “It’s no longer forest. Left to its own, a big piece of forest with fire in the middle will be fine in 20 years. But along the edges, it’s transitioning to something else.”
Ideally, humans would avoid starting fires in the first place (nearly every forest fire has a human origin), Coe said. But there's also evidence that global warming and clear cutting of the forest in general is leading to a climatic situation where drought is more common.
Longer dry periods are more likely to occur closer to human civilization. Image: PNAS
As you might expect, Brazil (and other Amazonian countries) aren’t exactly equipped to fight forest fires, meaning most of these have to die out naturally. Getting anywhere in the Amazon is difficult—finding the means of pumping water out of a hose to put out a fire is a relatively new concept in many places, but it’s not unheard of. Firefighters in Mato Grosso, Brazil, hired some of their first firefighting airplanes in 2012, and groups like USAID have been teaching indigenous people how to put out fires.
“Generally, it’s just people on the ground beating it out with what looks like these big rubber spatulas,” Coe said. “They have water trucks, but the logistics of getting people to the fire is very difficult. In drought years, they just burn until rainy season.”