On 21 May 2022, after hours of impassioned debate, members of Finland’s Green party voted to make theirs the first in the world to back nuclear power. Greens in Finland would now campaign not only for the lifespan of current reactors to be extended but also for new plants, with the technology recognised by their manifesto as “sustainable energy”.

It was a decision that upended decades of environmentalist orthodoxy – by campaigners who, in many cases, cut their teeth in opposition to nuclear. And, for Tea Törmänen, it was the culmination of years of campaigning.

She and others in the Finnish Greens for Science and Technology group had argued that only through the adoption of nuclear power and other technologies could human societies decarbonise fast enough to avert climate breakdown. Writing later, the biologist, who is also chair of Finland’s Ecomodernist Society, said: “For me it was a moment that was long overdue.”

As anxiety grows over the extent of climate and ecological crises, fear for the future is loading an ever more desperate calculus in favour of radical action. For some, this could include environmentalists embracing technologies previously regarded as unacceptable. But could Britain’s green movement go nuclear? Last month, Törmänen was in a London meeting with UK activists to see if it can.

RePlanet

are the pro-nuclear, pro-GMO vegans who have come to shake up the environmental movement. Newly formed of an international network of pro-technology environmental campaign groups, they believe doubling down on technology and progress is the key to solving the climate and ecological crises. Now, with funding from climate philanthropists, they are spreading out from a core in northern Europe with a plan to “pivot the mainstream” across the continent. But their proposals look set to put them on a collision course with traditional environmentalists.

In a video fronted by the environmental campaigner and Guardian columnist George Monbiot they have entreated the public to go vegan, calling for animal products to be replaced by fats and proteins grown in genetically modified microbial soup. In Germany they are campaigning for the government to end its phase out of nuclear power and in Finland and the Netherlands they have helped guarantee the industry’s future. At the EU level they successfully argued that nuclear should be included in its taxonomy of green energy sources, while at the same time campaigning against the bloc’s organic farming targets and longstanding ban on genetically modified crops.

Emma Smart outside HMP Bronzefield following her release from prison after being sentenced for taking part in a blockade of the M25 motorway. Photograph: Aaron Chown/PA

They have hired two seasoned activists, Joel Scott-Halkes and Emma Smart, to manage their UK campaign. With backgrounds in Extinction Rebellion, both have proven themselves committed to radical climate action. Scott-Halkes went on to join radical vegan offshoot Animal Rebellion, while Smart’s activism with Insulate Britain earned her spells in jail. A third British campaigner, the environmental writer Mark Lynas, a former staunch opponent of GM who reversed his views, is a co-founder.

RePlanet has its roots in a network of “ecomodernist” groups and societies established since 2015, after the publication of An Ecomodernist Manifesto. That document, signed by Lynas among others, upended traditional environmentalist philosophy. Instead of calling for humans to live in harmony with nature, for degrowth and moderation, the ecomodernists double down on technology as a means to minimise the human impact on Earth, while providing for a population of billions.

Land sparing lay at the core of the manifesto, with the aim of rewilding as much of the world’s surface as possible by concentrating human activities. Ultimately, they wrote, technology could “decouple” economic growth from planetary systems, and the “wise” use of nuclear power, genetic modification and intensive agriculture would lead “to a good, or even great Anthropocene”.

Activists in Finland, the Netherlands and elsewhere took up the charge. But in the UK, reception to the ecomodernists was frosty. Summing up criticisms at the time, Monbiot said ecomodernists “would wish away almost the entire rural population of the developing world”, and they had failed to interrogate the relationships between modernity and proletarianisation, uneven development and poverty. After a botched attempt to reach out across the political spectrum by teaming up with Owen Paterson, a Tory former environment secretary, Lynas admittedattempts to launch the movement in the UK had amounted to a “screw-up of impressive proportions”.

Now he is playing a key role in trying to revive ecomodernism. RePlanet, Scott-Halkes explained, had been born out of a process of “rebranding ecomodernism”, jettisoning bits of the philosophy that had “become problematic”. Over the past two years, he said, they had worked together with Monbiot to embed into their approach a critique of power. Where previously ecomodernists had been seen as naively pro-capitalist and pro-technology, RePlanet believe they have faced up to the nuances and dangers of the technologies they are proposing – and the dangers of progress in general.

Like classic ecomodernists, they see themselves as “pro-science and evidence-based” supporters of prosperity, who embrace progress, said Scott-Halkes. But there is a new emphasis on development and, befitting its sojourn in social democratic northern Europe, a new faith in “the power of the democratic state to take control of technologies, to develop technologies”.

Joel Scott-Halkes: ‘Nuclear is the most land-efficient energy source that has ever been invented.’ Photograph: Emilie Madi/Reuters

Precision fermentation and nuclear power are emblematic of the kinds of technical fixes they call for. Precision fermentation could, they claim, allow for the entire world’s protein to be produced from an area the size of London. It is not a pipe dream: the same technology is already used to produce most of the world’s insulin and citric acid; in the US, ice-creams containing precision fermented replicas of milk proteins are already on the market. But RePlanet says the technology must be “open sourced” to ensure its democratisation, with precision fermentation breweries in every town.

“We’re saying with precision fermentation, in particular, we need to get in there now, because this is food, this is sustenance,” said Scott-Halkes. “If this does come to dominate the global food system we should be advocating for democratic control of it right now. Otherwise, we’re actually genuinely screwed.”

Less easy to open source is atomic energy. But Replanet believe it is the only way for humanity to meet the energy needs of a rapidly developing world while decarbonising as fast as possible. “Nuclear is the most land-efficient energy source that has ever been invented,” Scott-Halkes said. “It is by various degrees 300 times more land efficient than wind power, 150 times more efficient than solar power, uncountably, 4,000 to 5,000 times more land efficient than biofuels. If you want space [for] rewilding, you need nuclear.”

Finland is the “gold standard” of what RePlanet hopes to achieve. Not only have ecomodernists there managed to persuade the Green party to adopt nuclear power, but in December the party’s council agreed to a dismantling of restrictions on GM. With 20 seats in Finland’s parliament, such policy decisions have force.

In the UK they have further to go. When pronuclear campaigners appeared on protests at Cop26 in Glasgow last year they were accused of being paid shills of the industry. Critics of precision fermentation argue it is a complicated technology prone to centralisation, when accessible, localised, resilient and above all natural food sources are needed.

Rob Percival, head of food policy at the Soil Association, which certifies organic food in the UK, described RePlanet’s Reboot Food campaign on Twitter as “akin to the rewilding movement getting hooked on GMO-steroids”. Percival said it was important for campaign groups to push boundaries, and he agreed with the potential for precision fermentation to displace intensive animal farming.

“But they are pushing this land-sparing concept to quite an extreme conclusion,” he said. “I think it’s unwise in that intensive systems have proven time and again to be liable to corporate capture, bad for the soil, heavily reliant on chemicals.”

Opponents of nuclear say it is far from living up to RePlanet’s promise. Dr Doug Parr, Greenpeace’s policy director, said the world needed alternative and clean sources of energy that are quick and cheap to deploy. “Nuclear is the opposite,” he said.

“The new plant at Hinkley C is over a decade behind schedule and billions over budget. The next one in line, at Sizewell C, may not even start generating energy until today’s newborns turn teenagers. Crucially, we don’t need new nuclear. Solar and wind technologies are a much cheaper and quicker way to cut carbon emissions, and studies show we can keep the lights on with a wholly renewable energy system. All we need is the political will to make it happen.”

Even Monbiot, who has helped to craft RePlanet’s updated ecomodernism, qualifies his support for the group’s ideas. He is known as an advocate for organic farming, which RePlanet has campaigned against. But he insists, nevertheless, that fresh thinking is needed to resolve the crises affecting the environment.

George Monbiot: ‘We can’t afford to be blinded by prejudices against certain technologies.’Photograph: David Levenson/Getty Images

“I broadly agree that we have to assess every issue from first principles, and we can’t afford to be blinded by prejudices against certain technologies,” Monbiot said wryly. “We have to assess them all case by case, and we might come down in slightly different places on some of those technologies, but broadly I think we are on the same page.”

RePlanet are not the only advocates of high-tech solutions to green problems. Taking his cue from Marx’s embracing of modernity as the grounds for revolutionary change, Matt Huber, author of Climate Change as Class War, dismisses degrowthers’ vision as “almost as austere as Pol Pot’s”. Adopting a more populist tone, the leftwingers clustered around the UK’s Novara Media news website have advocated for “fully automated luxury communism”, which went on to become the title of founder Aaron Bastani’s debut book.

Most significantly, those with the money and power to actually bring ideas into implementation also seem to back technological solutions. Vast sums have already been invested into GM, plans are afoot for direct CO2capture via huge industrial machinery and the cost-benefit analysis around geoengineering is increasingly regarded as worth the risk.

Ecomodernism may not, yet, be the most popular idea among those who are campaigning for a solution to planetary crises created by humanity. But it increasingly looks as though it may be the one we will get.