This story was produced by Grist and co-published with Agência Pública . ​

Brazilians filling out presidential ballots earlier this month saw three-term incumbent Luiz Inácio Lula da Silva pitted against Senator Flávio Bolsonaro. Environmental observers saw something else: a referendum on the future of the Amazon rainforest.

“We are very serious about the risks for the Amazon if Flávio wins the election, because he is a climate denier,” said Carlos Nobre, a climate scientist currently at the University of São Paulo’s Institute for Advanced Studies. “If this candidate is elected, certainly deforestation in the Amazon will increase. We are in a very serious situation.”

Flávio Bolsonaro, son of imprisoned former president Jair Bolsonaro, is campaigning on an agribusiness-friendly, deregulatory agenda . In the first round of voting, he finished 2.2 million votes ahead of Lula .…