The collapse of the Amazon rainforest is inevitable if Jair Bolsonaro remains president of Brazil, academics and environmental activists have warned amid a fresh government assault on protections for the forest.

Despite evidence that fire, drought and land clearance are pushing the Amazon towards a point of no return, they say the far-right leader is more interested in placating the powerful agribusiness lobby and tapping global markets that reward destructive behaviour.

The onslaught on forest safeguards has picked up pace. On Wednesday the lower house was due to vote on legislation that would reward land grabbers by legalising ownership of property that had been illegally invaded and cleared before 2014.

The previous day, the government shifted responsibility for forest fire satellite monitoring away from the National Institute for Space Research, a scientifically-robust organisation that had carried out the task for decades. Control has been given to the National Institute of Meteorology, which is under the influence of the agriculture ministry and the farming sector.

In the past few months, Congress has also diluted standards for environmental impact assessments and a committee has approved a bill – PL 490 – that has been described as the greatest assault on indigenous rights since the launch of the Brazilian constitution in 1988.

All of these measures punch holes in the Amazon’s protective framework and run contrary to scientific advice and the problems on the ground. Brazil is in the midst of a widening drought that has seen water inflows at some hydroelectric plants fall to 91-year lows. This is a cause and an effect of forest clearance.

Since Bolsonaro took power in 2019, deforestation and fire in the Amazon have risen to their highest levels in more than a decade. The past three months have continued that trend, though slightly behind last year’s peaks. Given the tinder-dry conditions in many parts of the Amazon, there are fears that the usual peak of the fire season in July and August could be worse than usual.

Scientists suspect the rainforest may be slipping into a series of vicious cycles. At a local level, land clearance and burning led to extended droughts and higher temperatures, which in turn weakens the resilience of the ecosystem and leads to more fire.

At a regional level, this can intensify drought because the respiration of the rainforest normally acts as a pump to drive humid weather systems across a wide area of Brazil, South America and the Atlantic. When the forest weakens, that pump is less effective.

There are also global repercussions because land clearance is turning the Amazon region from climate friend to climate foe. A study published in Nature reveals forest burning now produces about three times more CO2 than the remaining vegetation is able to absorb. This accelerates global heating.

Global market forces are partly responsible. Deforestation tends to rise when the prices of soy, beef and gold are high. No government of any stripe has completely managed to stop forest clearance in the past four decades. But government policies make a difference.

Amazon deforestation reduced 80% between 2004 and 2012 under the Workers party administration of Luiz Inacio Lula da Silva. Bolsonaro has steadily dismantled or discredited the mechanisms that achieved that – satellite monitoring, personnel on the ground and legislation to punish offenders and demarcate indigenous land and conservation areas.

“The main thing this government has done is to undermine the capacity of the state to tackle illegal deforestation,” said Marcio Astrini, executive secretary of the Brazilian Climate Observatory, a network of 50 civil society organisations.

In Congress, meanwhile Bolsonaro and the “ruralista” agribusiness lobby have put more supporters in key positions: Arthur Lira as leader of Congress, Carla Zambelli as chair of the lower house Environmental Commission and Bia Kicis as chair of the Justice Commission. These politicians have enabled the ruralistas’ agenda to go forward more aggressively.

“The Brazilian government is doing exactly the opposite of what needs to be done. It is actively stimulating deforestation through its policies,” said Erika Berenguer, an expert on Amazon land use change at the Universities of Lancaster and Oxford. “Until recently this was through decrees and ministerial policy changes that cut budgets for combating deforestation. Now, they have taken more important roles in Congress so we are seeing even more dangerous bills being passed.”

This is a global concern. The US president, Joe Biden, and the French president, Emmanuel Macron, have warned of the dangers posed by the decline of the rainforest. Supermarkets and financial organisations in the UK, Norway, Germany, France and Australia have threatened to boycott Brazilian products unless supply chains can be guaranteed deforestation free.

On Wednesday, 40 companies, include Iceland, Waitrose, Lidl, Tesco and Sainsbury’s issued an open letter warning that further erosions of environmental legislation and indigenous rights would force them to reconsider using Brazilian agricultural commodities. “We would like to reiterate that we consider the Amazon as a vital part of the Earth system that’s essential to the security of our planet as well as being a critical part of a prosperous future for Brazilians and all of society,” they said. Green groups said they now expected these companies to put their threats into effect.

Among many consumers Brazil is seen as a toxic brand, and Bolsonaro looks increasingly isolated on the world stage. But this international pressure has had little impact. Last month, Bolsonaro sacked his environmental minister, Ricardo Salles, after a tipoff by the US embassy about his alleged involvement in illegal timber smuggling. But Salles had already gutted the forest surveillance and enforcement bodies, and the real power behind him – the agriculture minister, Tereza Cristina Dias – remains in place.

This is partly because commodity prices remain high and demand is strong, particularly in China where the government puts resource procurement above environmental ethics and media pressure is limited by strict censorship. China is Brazil’s biggest market by a large margin.

But the major reason is the nationalist ideology of the president. According to Astrini, Bolsonaro is so exclusively focused on domestic politics that he is indifferent to international reputation or global markets. “He is the first Brazilian president who has an overt agenda of destroying environmental protections for political gain. He is not concerned about the country, only his re-election. It’s all about the electoral base,” Astrini says.

On a more positive note, he sees Bolsonaro as a catalyst for change. Since he took power, the Amazon rainforest has moved to the centre of political debate. Several candidates in next year’s presidential election now have zero-deforestation commitments in their manifestos.

“Even Lula is saying deforestation in the Amazon can no longer be supported by any Brazilian government. He never said this before,” said Astrini. “It is now clear that a solution for the Amazon can only be possible if we change government. There is no hope if Bolsonaro is re-elected president. It is either the Amazon or Bolsonaro. There is no space for both.”