At close to 90 years old, Brazil’s most venerated indigenous leader, Raoni Metuktire, has returned to the spotlight to challenge the man he calls the worst president of his lifetime, Jair Bolsonaro.

In an interview with the Guardian, the Kayapó chief said he wanted to speak out about the far-right administration’s plans to allow mining in indigenous territory and he warned that Brazil’s Amazon policies threatened global efforts to protect nature and address the climate emergency.

“Ï have seen many presidents come and go, but none spoke so badly of indigenous people or threatened us and the forest like this,” he said. “Since he [Bolsonaro] became president, he has been the worst for us.”

Raoni has lived through 24 administrations since first making contact with the world outside his rainforest home, and is at the forefront of a reinvigorated indigenous movement in South America’s biggest nation.

Along with Davi Kopenawa Yanomami, he is leading the resistance against government plans to open up the rainforest to land speculators, cattle ranchers, loggers and gold miners.

With his lip disc, beads, earrings and flowing grey hair, Raoni is probably the best-known Amazonian in the world. But he spent the first 18 or so years of his life unknown to anyone outside his forest community.

Raoni was a young, jenipapo-painted warrior when his tribe, the Metuktire Kayapó, was first contacted by non-indigenous invaders in the early 1950s, according to a new book by the veteran British explorer John Hemming. The intruders brought gifts of metal blades and beads but left behind European diseases such as malaria, influenza and measles that decimated the population.

In the 1970s and 1980s, Raoni was among the leaders of the often deadly fight against the BR-080 road, cattle ranchers and the Belo Monte dam. He rose to international prominence thanks to his friendship with the rock star Sting.

In the years that followed, he was feted by world leaders and met the pope, gaining a level of prestige and leverage that challenged the prejudices of the many Brazilians who see indigenous people as poor and uneducated. This helped the Kayapó to secure government recognition of their territorial rights across a vast chain of reserves, which formed the spine of a north-south firewall against deforestation.

“From many years ago, I fought in campaigns and appeared in the media. Then, when we won the victory of having our lands demarcated, I stopped because everything seemed fine, everything was tranquil,” he recalled. “But the new president threatens indigenous people, so I came back to fight again.”

Recent government figures show Amazon deforestation has surged to the highest level in a decade. Farmers and land-grabbers have started more fires to clear land, which is pumping huge quantities of carbon dioxide into the atmosphere, disrupting the water cycle and destroying the world’s most biodiverse land habitat. They have been emboldened by a government that has spent its first year weakening environmental protections, encouraging loggers and heaping scorn on conservation groups and forest dwellers.

Even before entering office, Bolsonaro frequently abused indigenous groups as an obstacle to economic development. “It’s a shame the Brazilian cavalry hasn’t been as efficient as the (North) Americans who exterminated the Indians,” he said in 1998. Now in power, he has promised to halt demarcation of new reserves and to open up territories to mining and agriculture businesses. Anthropologists have warned these actions will result in the genocide of uncontacted tribes.

Among the greatest threats is encroachment and environmental destruction by Brazil’s tens of thousands of garimpeiros (artisanal gold miners). Almost all are illegal, but Bolsonaro has expressed far more support for this group than previous state leaders. For him it is partly a personal issue. Bolsonaro’s father was a part-time gold miner, and the president has said he himself panned for gold while serving in the army.

“Bolsonaro is a garimpeiro. It explains the way he thinks, always trying to explore more land,” said Davi Kopenawa Yanomami. “He has a sickness in his head. He doesn’t think about others, or about the future.”

An author, shaman and environmentalist, Kopenawa is arguably the most prominent intellectual voice of the more than 300 different indigenous groups in Brazil. His book The Falling Sky outlines the very different cosmology of traditional forest peoples and warns that humankind is breaking the forest pillars that hold up the sky – an allusion that stretches beyond the climate crisis.

He said that in the past year Yanomami lands (which stretch across Brazil’s border with Venezuela) had been invaded by the biggest wave of illegal miners since the 1980s. “They are poisoning our rivers, killing our fish, and our people are starting to get sick with malaria again,” he told the Guardian.

Quietly spoken but defiant, Kopenawa said the problem was greater than Bolsonaro. Although the president had made matters worse, he said, mining companies from Canada, China and Japan were behind the push for resources. “Our politicians are selling our wealth. This brings no benefit to our people, just destruction. Who is getting rich? It’s the foreigners. The big companies are behind this.”

The threats are not just to the forest. Raoni has two bodyguards and is a target for attention-seeking nationalists who are trying to ingratiate themselves with Bolsonaro.

At a recent gathering of forest defenders in Altamira, a small group of land grabbers and farmers attempted to disrupt proceedings by surging towards the top table, prodding and shouting in the face of a young indigenous woman who was speaking about the killings of her people. Raoni wagged his finger reprovingly, a sign for half a dozen Kayapó warriors to push the intruders back to their seats.

The scuffle prompted exaggerated claims on rightwing social media that Raoni had “ordered an attack”. In fact, it was a defence – and a reminder of what has been happening across the Amazon for decades.

The jostling is now in the courts. The academic who organised the disruption has filed a criminal accusation against the Kayapó chief. The organisers of the event had already lodged a complaint against the protest organisers for making threats. Raoni said the fracas should not distract from the more important issue of how to save the Amazon.

“I was very sad at what happened. The people who want to destroy the forest came to disrupt things. I felt it was important to talk so I asked people to hold them back.”

The landowners were much quieter from that moment on. Civil society organisers claimed this as a victory for the majority in Brazil who want to protect the rainforest. They hope to build alliances across the Amazon and throughout the world to counter the threat posed by Bolsonaro and extractive industries.

There are signs this may be happening under the leadership of Raoni, Kopenawa and others. Indigenous tribes once fought each other as well as riverine settlers and quilombolas (descendants of runaway slaves who moved into the forest). Today, however, many of these different groups are allied against tree-clearing and river-poisoning intruders.

Raoni invited people across the world to join a peaceful resistance against the forces threatening indigenous territory, the Amazon and the world.

“They have the money and the guns. We don’t have that. I don’t have that,” he said after the interview. But with temperatures climbing and the forest under increasing threat, he said, it was necessary to act to help Brazil and avert a grimmer future for people around the globe.

“Nature is essential for us to breathe,” he said. “I hope people, not just in Brazil, will take my hand and join our forces to save nature, the forest and everything inside it, including the animals and the people.”