Brazil's presidential election may determine the fate of the Amazon rainforest — and the entire planet's climate

• Brazilians will vote for a new president on Sunday in the country's runoff election.
• Far-right President Jair Bolsonaro faces leftist former President Luiz Inácio Lula da Silva.
• The two candidates promise vastly different futures for the Amazon rainforest and the global climate.

The Amazon rainforest and the global climate are on the line Sunday, when Brazilians go to the polls to choose between President Jair Bolsonaro and his challenger, former President Luiz Inácio Lula da Silva.

The two candidates promise near-opposite fates for the Amazon, at a crucial moment when the rainforest is teetering on the edge of a dangerous tipping point.

If deforestation continues there at current rates, the Amazon will pass an irreversible threshold in just a decade or two, dooming it to turn into a savanna and release billions of tons of heat-trapping gases, scientists warn. That would accelerate a climate crisis that's already fueling dangerous extreme weather across the planet.

Bolsonaro promises to increase deforestation in the Amazon, while Lula promises to slow it.

Neither of them gained majority support in a first round of voting, so they go to a runoff election on Sunday. Polls have shown them neck-and-neck.

"It is the most consequential election in Brazil's history. But it's also the most consequential election on the planet," Christian Poirier, program director at the advocacy group Amazon Watch, told Insider. "Who wins that election determines our climate future."

Illegal mining, logging, and violence abound under Bolsonaro

Since his election four years ago, Bolsonaro has openly encouraged clear-cutting and burning in the Amazon for agriculture. His administration slashed the budget for the agency that enforces environmental laws in the Amazon, virtually defanging the rainforest's existing protections.

These policies have allowed illegal logging and mining to spread through protected areas and Indigenous territories. Pollution, deforestation, and violence have followed in their wake.

Instances of miners, loggers, and ranchers illegally invading Indigenous territory nearly tripled during Bolsonaro's administration, according to records from the Catholic Church's Indigenous Missionary Council. In 2020, a record 182 Indigenous people were murdered in Brazil, Cimi reported. In 2021, that number barely dropped, with 176 homicides.

Bolsonaro also campaigned on the promise not to demarcate any new Indigenous lands — designations that draw clear boundaries around their territories and would help protect the forest and Indigenous lives. He's kept that promise. According to monitoring from the Instituto Socioambiental, a Brazilian environmental and Indigenous organization, demarcation is pending for 241 Indigenous territories in Brazil.

"We are 1% of the Brazilian population that fights against the actions of almost 214 million Brazilians who think that the Amazon is just a forest with animals," Angela Amanakwa Kaxuyana, a Kahyana Indigenous activist and part of the leadership of the Brazilian Coordination of Indigenous peoples in the Amazon, told Insider.

Kaxuyana said loggers invade her tribe's land, Katxuyana Tunayana, which lies between the states of Pará and Amazonas. To her, Bolsonaro's reelection would mean that trespassing on and destruction of their land would continue.

"We are only sure that we Indigenous peoples want to curb deforestation, in order to preserve human life. There is no other way to keep people alive by drinking potable water, and breathing the air if it is not keeping the Amazon alive," Kaxuyana added.

The future Lula promises looks different. He's said he'll establish representation for Indigenous peoples in the Brazilian government, will crack down on illegal deforestation, and rebuild the country's environmental protection agency.

"There is no way to compare the two candidates," Kaxuyana said. [maybe move this down as the kicker?]

Lula's record with Indigenous peoples and environmental activists isn't perfect. Many fought against his project to build a hydroelectric dam on a river in the state of Pará.

Still, Kaxuyana said that Bolsonaro "would be the worst of the options in the context not only for indígenas, but for all Brazilian society and for humanity itself."

What happens in the Amazon affects the entire planet

If he wins reelection, Bolsonaro has promised to double down on his Amazon policies.

That could push the rainforest past a dangerous tipping point. With enough burning and clear-cutting, the local climate and water cycle could change so much that it causes mass tree die-off — an irreversible process that would eventually convert the forest into a savanna.

The Amazon could reach that tipping point in just 10 to 20 years if deforestation continues unabated, according to Carlos Nobre, a leading environmental scientist at the University of Sao Paola.

"More than one-third of the Amazon is really at the edge of this cliff," Nobre told Insider.

If that area grows to half of the Amazon, Nobre fears there is no recovery. Indigenous Amazonians would lose their homes. Hundreds of thousands of plants, animals, fish, bugs, and birds would likely go extinct, since so many exist only in the Amazon. And up to 140 billion tons of carbon currently stored in the rainforest could release into the atmosphere. That would lock in a catastrophic level of global warming, which could send other parts of the planet into their own tipping points, making the warming and extreme weather even worse.

To bring the forest back from that cliff, deforestation in the Amazon must stop immediately, scientists say. That requires enforcement of Brazil's current environmental laws, as well as new protections for the rainforest.

Lula's plan "lines up a lot with what myself and many other scientists are promoting," Nobre said.

One recent analysis by Carbon Brief, a website that covers climate science and policy, suggests that if Lula were to win the upcoming election, annual deforestation in the Amazon could fall by nearly 90% by the end of the decade.