A study published in The Journal of Politics has linked social media posts by former Brazilian President Jair Bolsonaro and three of his ministers in 2019 to the loss of up to 1,700 square kilometers of Amazon rainforest that year, researchers led by the University of Bonn reported.

The researchers estimated that figure, equivalent to as much as 420,000 acres, or nearly double the area of Berlin, after identifying 38 posts among more than 3,600 tweets from Bolsonaro and his ministers of agriculture, environment and foreign affairs that signaled illegal deforesters faced little risk of punishment, according to the study, led by Gustavo Magalhães de Oliveira, a postdoctoral researcher at Bonn’s Institute for Food and Resource Economics.

The team compared the timing of those posts against deforestation-alert data from the monitoring initiative MapBiomas Alerta and cross-referenced them with Twitter activity in 578 Amazon-region municipalities, finding forest clearing rose in the months when the posts appeared, according to the study.

The researchers found no accompanying change in municipal fines or enforcement actions tied to the statements, concluding the rise in deforestation stemmed from a shift in how loggers and ranchers perceived their risk of being punished rather than from any actual change in government policy.

Such messages spread through word of mouth.

That line, from Oliveira, describes how the researchers believe the posts’ effect extended beyond Twitter’s own audience, with the study also detecting similar deforestation patterns in areas with heavier television exposure to the same rhetoric. The effect was strongest in municipalities with high returns from agriculture and existing conservation restrictions, the study found, rather than in areas that voted heavily for Bolsonaro, pointing to economic incentive rather than political loyalty as the driver.

Deforestation under Lula

Bolsonaro lost his 2022 reelection bid to Luiz Inácio Lula da Silva, who has since increased enforcement in the Amazon. Annual deforestation in the Brazilian Amazon fell from 11,594 square kilometers in 2022 to 5,731 square kilometers in 2025, according to Brazil’s national space research institute, INPE, and satellite alert data show 2026 is on pace to register the lowest annual total since records began in 1988, according to an analysis by Carbon Brief.

Carbon Brief’s analysis, which modeled a scenario in which Brazil’s forest code went unenforced as a proxy for continued Bolsonaro-style governance, estimated that about 20,000 square kilometers of Amazon forest, an area comparable in size to Wales or the U.S. state of New Jersey, has avoided clearing under Lula since 2022. Aline Soterroni of the University of Oxford, who led the modeling underlying the analysis, called the estimate “relatively conservative” and said it did not capture illegal clearing that could occur under weaker governance.

An election with the forest at stake

Brazilians are due to vote in a first-round presidential election on October 4, with Lula facing Flávio Bolsonaro, a senator for Rio de Janeiro and the eldest son of Jair Bolsonaro, in a race polls show as essentially tied. A runoff is scheduled for October 25 if no candidate wins a majority.

Jair Bolsonaro, 70, was convicted in September 2025 of plotting a coup to overturn his 2022 election defeat and was sentenced to more than 27 years in prison, a ruling that also made him ineligible to run for office for eight years. He named Flávio as his political successor in December 2025.

Flávio Bolsonaro has pledged to end illegal deforestation by 2029. Claudio Angelo of the Climate Observatory, a Brazilian research network, said a Bolsonaro win could push deforestation “much higher” than during Jair Bolsonaro’s first term and warned of a possible “explosion of wildcat mining,” while Patricia Pinho of the Amazon Environmental Research Institute called the prospect of a Bolsonaro victory a “tremendous disaster.” Rews has previously reported on how Brazil has tried to expand renewable power while continuing to develop its oil industry regardless of who wins the presidency.