GABRIELA SÁ PESSOA SAO PAULO — Brazilian authorities are investigating whether a recent surge in wildfires in the Amazon rainforest have been set on purpose for political motives ahead of the second round of presidential elections later this month.

Fire counts across the biome, which have been near historic lows this year, have tripled since Oct. 4, when Brazilians voted in the first round of national elections. Sen. Flávio Bolsonaro, the son of former President Jair Bolsonaro, won 47% of the vote, while President Luiz Inácio Lula da Silva received 45%. The two will face off in an Oct. 25 runoff .

“The indications are that there has been a premeditated effort” to start the fires, Environment Minister João Paulo Capobianco told The Associated Press.

Capobianco and environmental enforcement officials flew over burned areas on Sunday and again on Wednesday. He said they observed fires in protected forest areas arranged in a distinct geometric pattern, suggesting they may have been deliberately set.

It’s not clear who might have started the fires or what their motivations may be. The wildfires have particularly hit Amazonas and Para states over the past few days. Smoke has disrupted daily life in Manaus, the capital of Amazonas and the largest city in the Brazilian Amazon. Public school classes were canceled and residents were urged to wear face masks.

Conservative politicians in Amazonas state have been the most vocal about the fires, according to monitoring by Barometro, a tool developed by Brazilian climate strategy agency FALA, part of the global Climate Action Against Disinformation coalition.

The analysis examined 165 posts about fires and smoke in the state from 41 politicians, finding that nearly 55% came from the right. Over the weeks, personal publications gave way to political disputes, with local politicians claiming credit for firefighting efforts or accusing authorities of failing to act.

“The same issue serves simultaneously as a public health warning, an environmental policy agenda and a campaign tool,” the report said.

The fires have also become a point of contention outside the Amazon, in an election campaign in which forest protection and climate change have received little attention.

Deforestation in the Amazon soared under former President Bolsonaro, while Lula has brought it back down to the lowest in a decade. Flávio Bolsonaro has denied climate change but said he is an environmental defender, without offering details on protecting the Amazon or supporting forest financing . In speeches, he has called for modernizing environmental laws, which many environmentalists read as loosening them .

The Bolsonaros most popular allies — Nikolas Ferreira, a lawmaker from the state of Minas Gerais, and reelected Sao Paulo Gov. Tarcísio de Freitas, both from southeastern Brazil — cited wildfires last week to criticize Lula’s government. De Freitas said Lula’s Workers Party were hypocrites and “disappeared” while the Amazon burned.

Lula did not address the criticism but said in a video posted Saturday on X that he had spoken with Amazonas Gov. Roberto Cidade and that the federal government was sending resources to support firefighting efforts.

“The people of Amazonas can count on the federal government. We are together in this fight to protect lives, preserve the forest and support those facing this emergency,” the president said.

Susana Braz, a 35-year-old biologist in Manaus who studies how toxic ash from Amazon wildfires affects the region’s rivers, said she could not sleep in her own bed because her smoke-filled bedroom felt like a barbecue grill.

“We come home, and the house is full of smoke,” Braz said. “We go outside, and there’s smoke everywhere.”People have tried to carry on as usual, but worsening smoke over the past 10 days has fueled frustration. “Are we really going to accept this smoke as normal, as if everything is fine and we just have to live with it?” she added.

The Amazon stores vast amounts of carbon and releases moisture that regulates weather far beyond South America. But climate change and deforestation are making it hotter, drier and more flammable . El Niño, a recurring climate pattern, can worsen heat and drought.

“Nearly all ignitions in the region are caused by human activity, mainly to renew pastures or clear land,” said Ane Alencar, science director at Brazil’s nonprofit Amazon Environmental Research Institute. “During very dry periods, those fires can escape.”Fire counts were expected to increase at this time of year with a developing El Niño, but the timing around elections is still notable, Alencar said.

“Over the past 10 days, we’ve seen fire hot spots nearly triple compared with the 10 days before the election, mainly around Manaus,” she said. “Something happened that led people to burn more.”João Morita, a coordinator at ICMBio, the federal agency that manages Brazil’s protected areas, has been on the front lines fighting fires in conservation areas in the Amazon. He said several factors could explain last week’s spike in the region, including residents of national forests burning crop plots, despite a ban.

“Fires start for all sorts of reasons. Some are retaliation for enforcement actions. Others are deliberately set with malicious intent. Any unauthorized burning is a crime, so there is a range of possibilities,” Morita said.

Officials and researchers have warned that El Niño’s effects on the Amazon could be worse in 2027 than this year.

In a statement to the AP, the Amazonas government said it met with federal officials over the weekend to discuss firefighting efforts and had declared a state of emergency in municipalities affected by wildfires.

“The measure takes into account worsening climate conditions caused by El Niño, with below-average rainfall and high temperatures forecast, which favor the outbreak and spread of fires,” the state government said.