In 2023, nearly
of forest burned
In 2023, nearly
hectares of forest burned.
The worst year of global forest fires ever.
This generated approximately
billion tons
of carbon emissions – roughly equivalent to the energy use of 291 million homes for one year.
2023
was also the hottest year on record
2024
is on track to be even hotter.
The Earth is getting hotter, and weather cycles are becoming more extreme, driving larger, more frequent and increasingly intense wildfires. The data is clear: forest fires are burning nearly twice as much tree cover as they were 20 years ago.
In addition to the damage wreaked on the ground, these fires expel billions of tons of carbon dioxide into the atmosphere, where they exacerbate global warming. This, in turn, fuels more extreme fire, releasing more carbon, and creating a climate-destroying downward spiral – a phenomenon scientists call the fire feedback loop.
“I think the cycle between climate change and wildfires is irrefutable,” said Sonya Dewi, director of Asia for CIFOR-ICRAF, in a podcast in 2022.
“Climate change increases the proneness of wildfires, and also the other way around. Wildfires emit a lot of carbon emissions into the atmosphere, which increases the speed of climate change.”
While the effects of the feedback loop are global, local factors make some regions particularly vulnerable to the increased risk of wildfires.
Here, we dive into four landscapes that are caught up in this vicious cycle, exploring what makes them susceptible and how they fit in the global climate crisis.
In September, fires in Portugal burned over 135,000 hectares and emitted at least 1.9 megatons of carbon.
The lack of species diversity is a concern for many. A quarter of forested land in Portugal is planted with eucalyptus, a non-native species used for paper and wood pulp production.
Eucalyptus trees catch fire relatively quickly due to their dry outer bark and abundance of natural oils. Moreover, eucalyptus trees grow up to 70 meters, or 230 feet, making them the tallest trees in Europe and a great fire spreader as flames fan out over their high branches.
Some research also suggests that the depopulation of rural areas has increased the likelihood of wildfires in Portugal. As people leave, land is left in an unnatural but unmanaged state, which can cause fuel to build up, especially when non-native species such as eucalyptus encroach.
Aside from driving global warming, the smoke from these massive fires can also impact human health. Just like cars and factories, fires emit plumes of small carcinogenic particles called PM2.5 that can enter the lungs and bloodstream.
In September, there were over 100 active fires in Portugal. Here’s a glimpse of the smoke they produced, as captured by Copernicus:
Record fires have been ravaging the Amazon and Pantanal wetlands. This is due in large part to the Amazon Basin’s worst drought in 45 years in 2023.
Longer droughts and heatwaves are direct results of the climate crisis, which causes drier soils, higher surface temperatures and lower humidity – all conditions that make land more prone to catching fire.
In fact, human-induced global warming made the June fires in the Pantanal 40 percent more intense and four to five times more likely to occur.
“We are seeing extreme fires increasing, and the common denominator is that when we look at climate anomalies, it is much drier now and the surface air temperatures are higher,” says Mark Parrington, a senior scientist in the Copernicus Atmosphere Monitoring Service (CAMS).
“What those hotter temperatures generally mean is that hot dry winds can exacerbate any existing fires and turn them into devastating fires.”
In short, the climate crisis is making the land more flammable and fires more severe.
“Most of these fires are related to deforestation."
However, “flammability is not enough for there to be a fire,” says Parrington. Unlike some other ecosystems, in which fires are part of the natural cycle, wetlands and rainforests are not adapted to burn, and fires rarely occur naturally.
“Tropical humid forests shouldn’t burn that easily,” said Ane Alencar, director of science for the Amazon Environmental Research Institute (IPAM), in a 2022 presentation on deforestation and fires in the Amazon. “Most of these fires are related to deforestation.”
Deforestation dries out the landscape, making surrounding areas of intact forest more susceptible to fires. Much of the deforestation in the Amazon is driven by agriculture, such as soybean farming and cattle ranching.
What’s more, fire is often used as a deforestation tool in the Amazon, meaning many of the ‘wildfires’ are intentionally set to clear land for agricultural expansion.
Globally, an estimated 75 percent of all wildfires are ignited by humans, either intentionally through arson or to clear land, or by accident, like when it spreads from burning trash.
Indonesia has seen some of the world’s largest-ever fires, most notably in 2015, when over 2.6 million hectares burned. These fires mainly occurred in peatlands – wetlands whose soil is made up of decaying organic material that stores high amounts of carbon.
When peatlands are burned, this carbon is released, producing higher emissions than many other ecosystems.
Peatlands are also often drained to make room for agriculture, which not only releases the stored carbon but also makes them more susceptible to fire.
What’s more, fires in peatlands can smolder underground for extended periods, making them challenging to put them out, says Herry Purnomo, a scientist with CIFOR-ICRAF who has researched the connections between fire, local politics and economy in Indonesia.
But even when vulnerable, peatland fires still need a spark to ignite them.
In the tropical archipelago of Indonesia, 98 percent of wildfires are due to human activity – particularly slash-and-burn agriculture.
This involves cutting and burning vegetation to clear land for planting while simultaneously fertilizing it with the nutrients from the ashes. This creates fertile plots, called swidden, which only remain productive for a few years.
Farmers often choose slash-and-burn as it is more financially viable than other methods of preparing land.
It costs farmers in Indonesia just USD 20 per hectare to prepare land using planned burns, compared to USD 300 per hectare using a tractor, Purnomo explains.
“There is a lot of economic incentive to burn,” he says.
These planned burns, which are damaging in and of themselves, can also spread to surrounding areas, which, in Indonesia, include degraded forests and peatlands with ample dry vegetation that can quickly ignite.
But this situation has improved in recent years, according to Purnomo, who cites the benefits of the Indonesian government shifting 60 percent of its fire prevention efforts to indirect causes of fire.
Purnomo says better educational efforts are helping communities transition to alternative ways of preparing land and maintaining their livelihoods that don’t degrade peatlands and wetlands at large.
“I am optimistic,” he reflects on the future of land use and fires.
“There is still work to be done to provide assistance and convince communities not to use fire. It is very important to attract green investments and environmental funds to help people prepare land without fire.”
While fires may not often occur naturally in the tropics, they are to be expected in the boreal forests of northern Canada, where fires clear understory shrubs to make space for new trees and return nutrients to the soil.
And while humans spark most fires globally, roughly half of all fires in Canada are started by lightning, says Canadian Forest Service researcher Piyush Jain.
However, as the climate crisis continues to change temperatures and weather patterns, lightning patterns could change as well, he says.
“Lightning is essentially a product of the available moisture energy in the atmosphere,” Jain explains.
“Both of those things will increase under climate change, and so there may be capacity for increased lightning, which, combined with drying-out fuels, could create conditions for even more fires than weather alone could predict.”
What’s more, climate change is pushing these natural fires to the extreme. On average, forest fires in Canada have doubled or tripled in size in the past two decades, and the country has seen severe back-to-back fires in 2023 and 2024.
Historically, fires would only return to the same forest every 100 to 150 years, Jain says, adding that the increasing severity, length and frequency of fires could severely impair the forest’s ability to regrow.
Additionally, research suggests that successive fires can disrupt soil’s ability to sequester carbon – further feeding the fire feedback loop.
In 2023, Canada’s wildfires burned 8 million hectares of forest – emitting more carbon dioxide than all but three of the world’s most polluting countries, and sending smoke as far as Europe.
These local factors increase the likelihood of wildfires in the regions we’ve looked at, but the underlying effects of climate change are driving them to the extremes.
Human activity is both directly and indirectly causing global temperatures to rise, fueling longer-lasting and more frequent fires.
These intensified fires expel large amounts of carbon dioxide, which when accumulated in the atmosphere trap and radiate heat, further fueling global warming.
Moreover, more severe fires lead to drier, hotter conditions, which leaves vegetation brittle and more exposed to future fires.
There is only one way to end the cycle and bring wildfires under control again: we have to tackle the global climate crisis by phasing out fossil fuels.
While it’s difficult to estimate how much carbon dioxide is emitted by wildfires, it’s clear that fossil fuels are the biggest contributor to global carbon dioxide emissions – and it’s not even close.
Burning fossil fuels and industrial processing account for about 90 percent of all global carbon emissions.
At COP28 in 2023, countries agreed to merely “transition away” from fossil fuels, rather than phasing them out.
This was hailed as a historic achievement as it was the first time such an agreement had been reached at a UN Climate Change Conference.
But in the year since, emissions from fossil fuels have further increased by 0.8 percent, reaching an all-time high.
Last month, Azerbaijan hosted COP29, becoming the second consecutive petrostate to host the annual UN climate talks, and fossil fuel lobbyists once again outnumbered most country delegations.
The final agreement, which was heavily criticized for offering Global South countries just a small fraction of the climate finance they need, made no mention of fossil fuels at the insistence of Saudi Arabia.
Instead, countries have put off any further discussions on fossil fuel phaseout until the next round of UN climate talks in Bonn, Germany, in June 2025.
Until then, the fire feedback loop keeps burning.
Written by: Ava Eucker
Graphics by: Inês Mateus
Produced by: Eden Flaherty
