As smoke poured into Sao Paulo, Brazil, the fires raging across the Amazon sparked international outrage.

Some in the international community were quick to blame Brazilian president Jair Bolsonaro for the flames.

But Bolsonaro pointed to a dozen possible reasons for why the fires intensified, including blaming non-governmental organisations (NGOs).

“I am under the impression it could have been set by the NGOs because they had asked for money. What was their intention? To bring about problems for Brazil,” he said, on 21 August.

His environment minister, Ricardo Salles, claimed the weather intensified the blaze. Environmental activists pointed to large agribusinesses.

Amazon rainforest swept by fires: In pictures Show all 25 1 /25 Amazon rainforest swept by fires: In pictures Amazon rainforest swept by fires: In pictures Fire rages in the Amazon rainforest in the Brazilian state of Rondonina on August 23 Reuters Amazon rainforest swept by fires: In pictures Smoke billlows from burning tracts of the Amazon rainforest in the Brazilian state of Para on August 23 AFP/Getty Amazon rainforest swept by fires: In pictures Fire rages in the Amazon rainforest in the Brazilian state of Rondonina on August 23 EPA Amazon rainforest swept by fires: In pictures Land in the Amazon rainforest left scorched in the fires in the Brazilian state of Rondonina on August 23 AFP/Getty Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Rondonia, Brazil on August 23 AFP Amazon rainforest swept by fires: In pictures Fire tears through a farm in the Brazilian state of Mato Grosso AP Amazon rainforest swept by fires: In pictures An area of the Amazon rainforest left scorched in the fires in the Brazilian state of Amazonas on August 24 AFP/Getty Amazon rainforest swept by fires: In pictures Satellite images show a series of fires in the southwest Brazilian state of Rondonia on August 15 AP Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Rondonia, Brazil Reuters Amazon rainforest swept by fires: In pictures A satellite image released by NASA shows the active fires that have been detected in the Amazon region EPA Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Amazonas, Brazil Reuters Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Rondonia, Brazil Reuters Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Rondonia, Brazil Reuters Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Amazonas, Brazil Reuters Amazon rainforest swept by fires: In pictures Indigenous people from the Mura tribe wallk in a deforested area inside the Amazon rainforest in the Brazilian state of Amazonas on August 20 Reuters Amazon rainforest swept by fires: In pictures Fire tears through a farm in the Brazilian state of Mato Grosso AP Amazon rainforest swept by fires: In pictures Smoke billows from a stretch of fire in the Amazon rainforest in the Brazilian state of Rondonia on 23 August AFP/Getty Amazon rainforest swept by fires: In pictures Smoke billows during a fire in an area of the Amazon rainforest in the state of Amazonas, Brazil Reuters Amazon rainforest swept by fires: In pictures Indigenous people from the Mura tribe wallk in a deforested area inside the Amazon rainforest in the Brazilian state of Amazonas on August 20 Reuters Amazon rainforest swept by fires: In pictures Smoke billows from a stretch of fire in the Amazon rainforest in the Brazilian state of Rondonia on 23 August AFP/Getty Amazon rainforest swept by fires: In pictures A view of logs felled illegally in the Amazon rainforest are seen in sawmills in the Brazilian state of Amazonas on August 22 Reuters Amazon rainforest swept by fires: In pictures A scorched patch of land in the state of Mato Grosso in Brazil on 20 August EPA Amazon rainforest swept by fires: In pictures Several fires are seen burning in the Amazon rainforest in this satellite image taken by NASA on 11 August AFP/Getty Amazon rainforest swept by fires: In pictures Smoke billows from a stretch of fire in the Amazon rainforest in the Brazilian state of Rondonia on 23 August AFP/Getty Amazon rainforest swept by fires: In pictures The sunsets behind clouds and smoke from fires in the Amazon rainforest in the Brazilian state of Rondonia on 18 August EPA

“Dry weather, wind and heat caused the fires to increase greatly throughout the country. ICMBIO and IBAMA brigade members, equipment and aircraft are fully available to the States and already in use,” said Salles, on 20 August.

And Delaney, a 2020 Democratic presidential candidate, said it was Donald Trump’s trade war with China that started it all.

“In reality, [the Amazon wildfires are] directly related to trade,” Delaney said, on 27 August. "The fact that US farmers can’t sell soybeans to China has created an opportunity for Brazil to sell soybeans to China.

“As a result, farmers are tearing down the Amazon to grow soybeans.”

All of those explanations cannot possibly be accurate simultaneously because some of them seem to contradict each other. So what’s going on here? Let’s dig in.

Fires in the rainforest don’t start themselves, but that doesn’t mean they are unusual.

Every year in the dry season, roughly between August and October, deforestation fires are set by people who clear land for a variety of reasons – farming, ranching, mining, illicit activities, infrastructure.

Brazil’s National Institute for Space Research (INPE), which tracks fires in the Amazon, reports that the number of fires detected through September 2019 is up nearly 50 per cent from the same period in 2018.

That said, the first nine months of 2019 have also seen roughly 10 per cent fewer fires than the same period in 2017.

Nevertheless, 2019 has seen just over 10,000 more fires than the Brazilian Amazon has seen on average over the past decade.

Douglas Morton, chief of the Biospheric Sciences Laboratory at NASA’s Goddard Space Flight Centre, uses satellite imagery to track fire activity and deforestation around the world.

He said the Amazon is not on track for a record this year.

“Our satellites allow us to go back to 2000 and compare 2019 fire activity all the way back to the beginning of this century,” Morton said. “Fires in 2019 haven’t reached the levels they were at in the early part of the 2000s.”

Still, what or who is causing the uptick in fires? Let’s break down the various hypotheses.

The weather

Scientists say climate conditions are always part of the fire equation, determining how quickly fires can start and spread.

Weather patterns such as El Niño can bring drought, making the land more flammable. And wind can make deforestation fires more intense.

But when fires are amplified because of drought, they can stretch past the typical end of the dry season in October. It’s not clear whether that will happen this year, Morton said.

However, he added, the fires, “are early in the dry season, which tends to be more motivated by economic pressures rather than climate conditions” and “are in the locations we expect to see fires for deforestation”.

In other words, although weather will always have a role, all signs suggest that the uptick in fires this year is not caused by it.

Non-governmental organisations

Bolsonaro suggested NGOs started the fires as retribution after his administration withdrew funding.

Our Brazilian fact-checking colleagues at Aos Fatos examined this claim and found no evidence to support it.

Roughly translated from Portuguese, they reported: “In addition to not presenting any material to substantiate his accusations, [Bolsonaro] errs in stating that he has cut the transfers of funds from the Amazon Fund to NGOs. This is because, for this to happen, a decree is still being issued.”

Just 24 hours later, Bolsonaro conceded that farmers might have started the fires.

Large agribusiness and Trump’s trade war

That brings us to agricultural businesses.

The logic behind these theories, promoted by environmental activists and Delaney, is simple: American farmers can’t sell soybeans to China.

Brazilian agricultural businesses are picking up the slack, but to do that, and make maximum profit, they need to grow more soybeans, which means they need more land.

This theory excludes one key factor: Brazil has some of the most strict environmental regulations in the world.

Monica de Bolle, a senior fellow at the Peterson Institute for International Economics, said any company exporting crops has already “transformed their business practices in order to be sustainable” and to comply with Brazil’s strict regulations.

The big soy producers are “very concerned about losing market share”, de Bolle said.

They are nervous about “how international markets and [their] buyers are going to react” to the fires, she said, not whether this is an opportunity to expand their farms.

Besides, she added, “they may operate in areas adjacent to the forest, but they’re not in the Amazon”.

De Bolle’s assessment seems to check out.

Blairo Maggi, a former agriculture minister and the main shareholder in one of Brazil’s largest grain trading groups, told a Brazilian media outlet that he was concerned that growing international outrage could lead to Brazilian exports being blocked.

Beyond business concerns, University of Maryland professor Matthew Hansen said, there were practical reasons the large soy companies were unlikely to be responsible.

“If you’re a big soy producer, there’s so much intensification around the larger agro-industrial farms ... you don’t want fire around,” he said.

Plus, he added: “most of the crop expansion is happening on the Cerrado. It’s not happening in the Amazon rainforest biome.”

However, environmentalists point out that big soy producers have a history of not steering entirely clear of the Amazon.

A recently built highway through the Amazon is key to transporting goods.

And while the soy sector signed a voluntary agreement in 2006 not to source commodities made on land deforested after 2006 (eventually pushed back to 2008), critics say loopholes allow companies to work around it.

The Washington Post found no evidence to support this theory.

Still, soybeans aren’t the only commodity produced in this area of the Amazon.

Many farms grow crops and have cattle, which as environmental activists are quick to point out, can mean that the big exporters may source product (inadvertently or not) from farms that may participate in some kind of annual burning.

US soybean farmer speaks of losses from Donald Trump's trade war with China

In the 2017 “Cold Meat” scandal, the Brazilian Institute of the Environment and Renewable Natural Resources, or IBAMA, identified JBS and 13 other companies that sourced cattle from illegally deforested areas. JBS denied the claims in 2017.

Satellite maps make the distance between the fires and cropland clear.

Hansen and his team at the University of Maryland’s Global Land Analysis and Discovery laboratory overlaid the location of fires that have burned this year with the location of crop land in 2018.

“The fire is very removed [from the crop lands] along the frontier with the Amazon,” Hansen said. It is “clearly related to some of their land use – in this case likely cattle ranching expansion.”

However, he added, once land is cleared, it can be difficult to determine exactly why until crops show up or don’t. And land uses change – former cattle pastures become farms, and farms rotate crop types.

When PolitiFact looked into Delaney’s claim in August, his campaign pointed “to a number of press reports that drew a connection between Trump’s trade war with China and the burning Amazon rainforests”. Ultimately, however, they found his claim false.

Bolsonaro’s rhetoric

Bolsonaro campaigned on the idea that the Amazon is an untapped natural resource that should be used for the “well-being” of the Brazilian people.

And the international community was quick to point to his rhetoric and his policies as the cause of the uptick in fires.

Still, a little history goes a long way in untangling how Bolsonaro does,or does not, fit into the picture.

In the early 2000s, another bout of international outrage over fires in the Amazon pushed the Brazilian government to implement a national action plan to deal with deforestation. From 2004 to about 2014, it was incredibly successful.

The Federal Plan of Action for the Prevention and Control of Deforestation in the Legal Amazon relied on real-time collaboration between government agencies to stop deforestation fires as they were happening.

But in 2015, the Brazilian economy fell into a deep recession, and deforestation rates started to rise again.

“It wasn’t that the government was no longer focused on [the anti-deforestation] environmental policies,” de Bolle said.

“It was really that, because of this very deep recession, they ran out of money, and they were no longer able to fund a lot of these initiatives.”

By 2018, the Brazilian economy started to recover and was able to devote funding to the agencies responsible for monitoring fires. The number of fires began to decline.

That’s where Bolsonaro comes in. He was elected in October 2018.

In July, he called the rise in deforestation – reported by Brazil’s National Institute for Space Research – “a lie”. The head of the organisation was fired shortly after, and the public spat with Bolsonaro was cited as the reason.

Bolsonaro moved swiftly to defund a variety of initiatives across the government – including the interagency collaboration aimed at curbing fires.

On 5 August, a Brazilian newspaper reported an organised day of burning, called ‘Fire Day,’ scheduled for 10 August around Novo Progresso in the state of Para.

The day was reportedly organised over WhatsApp to show support for Bolsonaro’s environmental policies.

Ivaci Matias, a veteran Brazilian journalist, said Fire Day “was meant to support the ideas of [Bolsonaro], who was dismantling IBAMA’s fiscalization scheme, saying that there would be no more arbitrary fines. So they understood that the president was with them”.

A Brazilian federal prosecutor asked IBAMA to prevent the coordinated burning.

What to do in the Amazon

But when it requested support from state police, the police refused – even though they have a history of collaboration.

An investigation from the Federal Public Prosecution Service (MPF) ended with a recommendation that the police resume support of IBAMA.

Roughly translated from Portuguese, the MPF also wrote: “Had it not been for the PM’s[military state police] denial of support to Ibama, the event that became known worldwide as ‘fire day’ could have been mitigated or even avoided.”

Matias said fires for pasture are usually sparked in October, maybe the end of September. And then the rain comes and washes them away in November. “This fire was criminal,” he said.

Satellite imagery confirms that there was a distinct uptick in the number of fires on 10 August. And according to NASA imagery, Morton reported, it “continued after [10 August] across the southern Amazon. That actually is the start of increased regional fire activity.”

But satellites cannot confirm motive. Brazilian authorities are investigating who is behind Fire Day and how widespread the initiative became. After all, it’s just as possible that some people saw their neighbours burning and decided it was time to burn.

So who or what started the fires in Brazil’s Amazon?

The ongoing investigation proves the answer is not so clear-cut – and none of the initial hypotheses checked out on their own.

The timing of the fires points to people who wanted to clear as much land as quickly as possible.

The location generally suggests the fires were probably not started by major soy producers. At this point, we can’t be certain until crops appear (or don’t) on cleared land.

But the motives vary. Some fires were set as part of a coordinated action to show support for Bolsonaro’s environmental position.

Others were started as part of annual burnings. History shows that this kind of uptick in fire activity happens when there is less oversight, and that can be brought on by an economic downturn or government policy changes.

In other words, Bolsonaro’s ambivalence towards environmental protections may not have directly lighted the first match, but it was a nod of approval to those who did.