Unless every poll is wildly wrong, Brazil will probably elect a racist, sexist, homophobic advocate of torture at the end of this month. The former army captain Jair Bolsonaro nearly won outright in the first round, securing the votes of almost 50 million people – despite his extreme views being well known.

What is less well understood, however, is the catastrophic environment implications of his rise to the brink of power. And in this, Bolsonaro is not unique: around the world, diminishing resources are fuelling a global rise of authoritarian leaders dedicated to doing the bidding of some of the world’s most environmentally damaging interests.

The Brazilian election results were announced on 8 October – just as climate scientists were issuing their most dramatic warning yet that humanity has just 12 years to slash emissions or suffer the consequences of dangerous global warming. If countries do not start planting trees and cutting fossil fuels now, they said, then it will be impossible to prevent a rise of more than 0.5C, which would completely eradicate all of the world’s corals and irreversibly disrupt weather systems, bringing droughts, floods and extreme heat that will push hundreds of millions into poverty.

History tells us that when environments deteriorate, societies turn to 'strongmen' and zealots rather than pragmatic leaders

History tells us that when environments deteriorate, societies turn to supposed strongmen and religious zealots rather than smart, pragmatic leaders. That is happening now. In addition to the dictatorships of China, Russia and Saudi Arabia, a growing number of young democracies have relapsed into authoritarianism: the Philippines under Rodrigo Duterte, Turkey under Recep Tayyip Erdoğan, Egypt under Abdel Fattah el-Sisi, and next, it would seem, Brazil under Bolsonaro. And underlying this is environmental stress, which has been building for over two centuries.

Starting in Britain, the carbon-capitalist industrial model has long been extracting minerals and organic resources, and discharging the waste into the air, sea and land. As more nations developed, they exported their environmental stress to the next country rising up the economic ladder.

Now that this paradigm is being replicated by the world’s most populous country, China, there are very few places left to absorb the impact. Competition for what is left is growing. So is violence and extremism. Centre-ground politicians who once talked chummily about “win-win solutions” have been pushed to the sidelines. No one believes this any more. Voters may not see this in environmental terms, but consciously or subconsciously they know something is broken, that tinkering is no longer enough.

Facebook Twitter Pinterest A soy plantation in the Amazon rainforest near Santarém, Pará, north Brazil. Photograph: Ricardo Beliel/LightRocket/Getty Images

In the US, with massive support from the fossil-fuel industry, Donald Trump has undermined the Environmental Protection Agency, opened up swaths of national parks to industry, cut pollution controls and promised to pull out of the Paris accord. In Australia, Malcolm Turnbull was ejected from power by his colleagues because he tried to fulfil promises to cut carbon emissions. And now in Brazil, voters are backing a politician who has vowed to pull his country out of the Paris deal, abolish the main government agency tackling deforestation and end the demarcation of indigenous land.

Bolsonaro has the backing of agribusiness and mining leaders, who are rubbing their hands in glee at the prospect of an Amazon denuded of its greatest protections. The markets – which are heavily driven by extractive industries – also love him. The main stock index and exchange rate of the Brazilian real spiked after his first round win. An editorial in the Wall Street Journal endorsed him as a “conservative populist”.

Such neo-fascist politicians should not be blithely dismissed. They are the hired guns of the industries working against the Paris accord and other international agreements that aim to prevent further environmental catastrophes, which hit the poorest hardest. Their “anti-globalism” is first and foremost anti-nature and anti-future. An extraction-first approach may bring economic benefits in the short term, as cronies and campaign donors clear more forests, open up plantations and dig more mines – but the profits are concentrated while the environmental stress is shared.

The great fear climate scientists have is that a warming planet could create feedback loops that will make everything much worse. But there has not been enough study of economic and political feedback loops. How drought in China puts pressure on the Amazon to produce more food and clear more forest. Or how powerful business interests will choose a dictator over a democrat if it means easing environmental controls that threaten their ability to meet quarterly growth targets.

Bolsonaro's pledge to return Brazil to past alarms survivors of dictatorship Read more

We are already seeing a widening gap between politicians and scientists. While the latter urge more ambitious climate action, the former know they will receive more campaign funds if they oppose emissions cuts, support extractive industries and weaken pollution regulations. It is not just dictatorships. Britain is pushing ahead with fracking, Germany with coal and Norway with oil exploration.

At some point, voters will realise that ecological stress is at the core of the world’s current woes. The aha! moment may be when water grows prohibitively expensive, or crops fail owing to successive heatwaves, or the refugee crisis sparks war, but at some point the weakness of the strongmen will be apparent, and people will seek change. The danger is, by then it may be too late. Climate and politics alike will have passed a tipping point, leading to social chaos and the morphing of populists into full-blown dictators-for-life.

That is not yet inevitable, but the risks are growing. What has become clearer than ever is that the best way to avoid climate and ecological collapse is by voting for leaders who make this a priority. It will be impossible to fix the economy unless you first fix the environment. The global instinct for radical change is right, but unless that is geared towards ecological rebuilding the world’s democracies may go extinct before the corals do.

• Jonathan Watts is the Guardian’s global environment editor