The Amazon rainforest: could it become a desert?
Fire consumed the outskirts of the Amazon rainforest in August. With mortality rates of tropical trees increasing, we ask: could the ecosystem be tipped into a barren desert environment?
News of increasing fires in the Amazon rainforest spread around the globe in August as huge areas were set alight to clear the land for machine farming. The figures that emerged shocked the planet: there had been nearly 50,000 fires in the first eight months of this year, up 84 per cent from the same period in 2018. If this trend continues, the whole rainforest ecosystem is at risk.
The Amazon rainforest is not equipped to deal with fire. Unlike other ecosystems, such as the African savannah, where wildfires are common, the rainforest is too wet to ever catch alight naturally. Any fire started there has been ignited by human activity.
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Not all fires in the Amazon are illegal, however. In some states, land owners are able to apply for a licence to deforest up to 20 per cent of their property – commonly done to clear areas to build on, farm or mine. To do this, trees are felled and laid out under the hot sun. After a number of weeks, they are dry enough to burn. But this year, many states have had a ‘fire ban’ to prevent this method of deforestation. The Amazonas state had such a ban, yet fires have still been recorded there.
Adriane Esquivel-Muelbert is an ecologist at the University of Birmingham, studying the effects of climate change on forests, particularly in Brazil, her home country. Previously, concerns were increasing numbers of wide-spread droughts, which kills millions of trees and threatens the biodiversity of the rainforest.
This year alone (at time of writing), Brazil’s National Institute for Space Research (INPE) records show 197,386 fires in South America. Half of these were in the Amazon rainforest. Esquivel-Muelbert says fire is used as it clears the land completely, flattening it to allow for the big machines that will be used by farmers.
“The forest recovers from a drought after a few years, even though the types of trees there might not be the same. Whereas fire is complete destruction,” she says.
It’s a vicious cycle. As more trees die, the surrounding areas become even hotter and drier. “At the moment, the rainforest has this closed canopy that shades and protects trees,” explains Esquivel-Muelbert. “Once you take that away, it opens the canopy, and you have more space in the rainforest and more of the hot, tropical sunlight pouring in.”
As the cycle continues, the state of the Amazon as a rainforest could become threatened. Some have said that we are nearing a ‘tipping point’, at which the rainforest will irreversibly become a desert – a process that’s been dubbed ‘desertification’ by some media.
The reality is closer to a ‘savannahfication’, says Esquivel-Muelbert. “If this deforestation increases, it could change the climate in the rainforest to one that is less favourable to the tropical tree species, and more favourable to ones like those found in a savannah.
“At the tipping point, the Amazon shifts to the state of a savannah. It’s a point of no return.”
Not only would this be a huge loss of plant and animal biodiversity, but a savannah is a less effective carbon-sink than currently offered by the rainforest.
The tipping point is a hypothesis, explains Esquivel-Muelbert, but researchers have seen indications that it could be happening. “We have seen a shift in species there. Droughts increase the mortality of those trees that prefer rainforest conditions, while the more drought-tolerant species become favoured by the new climate.”
The areas that remain in the rainforest state are threatened by the hotter, drier conditions brought by surrounding savannah. It’s hard not to imagine this ‘savannahfication’ as all-consuming, spreading itself like fire.
How close are we to a tipping point? Unfortunately, it’s hard for scientists to predict. “It depends on how much we preserve the forest,” says Esquivel-Muelbert. “We need to act now to prevent high mortality rates and try to reverse this trajectory.”
Most of the Brazilian Amazon is indigenous land. “Deforestation doesn’t only kill trees, it kills people,” says Esquivel-Muelbert. “So many cultures live together [in the Amazon]… but it’s almost like a Wild West – there are no rules, no authority. These people are threatened by illegal miners, loggers. The communities that live there need to be respected, they need to have a voice and we need to make sure they are safe.”
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The state of the Amazon rainforest is a concern for the world, says Dr Shanan Peters, a geoscientist at the University of Wisconsin-Madison. Not just because of the oxygen they produce, but the carbon dioxide they lock up.
“To say the Amazon is the ‘lungs of the planet’ is kind of a misleading statement,” says Peters. “We could burn every living thing on Earth – all the trees, all the grass – and still not run out of oxygen for many, many generations of humans, but we would be devastated by the doubling of CO2 that would happen instantly. The story of what is happening right now in the rainforest is, in my view, articulated by the impact it’s going to have on CO2. [The Amazon fires] are exacerbating our climate crisis.”
“For me, [this year’s fires] are clearly linked to the rhetoric of the president,” says Esquivel-Muelbert, commenting on the environmental policies of Brazil’s current president, Jair President Bolsonaro, which have been accused of failing to protect the rainforest. “But also, in a way, everyone is responsible. The actions we carry out here in the UK affect the Amazon. We have to realise the things we consume might come from farms in the Amazon… The global community needs to realise that everyone needs to help to preserve the rainforest we have remaining.”
With thanks to Erika Berenguer. Erika is a senior research associate at the Ecosystems Lab at the University of Oxford.
Amy is the Editorial Assistant at BBC Science Focus. Her BA degree specialised in science publishing and she has been working as a journalist since graduating in 2018. In 2020, Amy was named Editorial Assistant of the Year by the British Society of Magazine Editors. She looks after all things books, culture and media. Her interests range from natural history and wildlife, to women in STEM and accessibility tech.