When it wasn’t addressing the immediate constitutional chaos and descent into Trumpian populism, the Labour conference turned to the minor matter of stopping climate change.

The charge was led by Labour for a Green New Deal (Labour GND), a coalition of Labour organisers, union organisers and environmental campaigners. I met one of its co-founders, Chris Saltmarsh, in the central Brighton Wetherspoons that has become the conference HQ for the six-month-old campaign.

It just so happens that it was one of the Spoons that was the site of a strike last year that won workers a pay rise. Labour GND activists had colonised the back of a mezzanine area and were working away on laptops, making the scene a bit like a nationalised Wetherspoons x WeWork crossover (“it has everything you need!” the group’s press officer tells me).

It was the day before conference voted through his motion, and Saltmarsh was running on adrenaline after a tiring few days. The police initially denied him security clearance to the conference – he assumes because of a previous conviction for blockading an anti-fracking site, though he hasn’t received an explanation. He was also busy trying to get Labour to adopt what is being touted as the most radical environmental policy of any Western political party that could feasibly win an election. "The sense that this is an incredibly historical moment is really dawning on me,” he said.

But what actually is a Green New Deal? Saltmarsh reckons that everyone can agree up to the following definition: “A mobilisation of every area of the economy, through investment and regulation primarily, to really quickly decarbonise while assuring prosperity and improving living standards and ensuring good unionised jobs for everyone.”

For Saltmarsh and his GND comrades, that means socialism: “Democratic public ownership has to be absolutely central... The time has come for democracy and the state to take charge of this effort and be like, ‘OK, it’s time to discipline capital, it’s time to take this beyond market forces’.”

And it means internationalism – climate change is “rooted in capitalism and colonialism which are structures imposed by the UK”, says Saltmarsh.

Labour GND is pushing for carbon neutrality by 2030 – faster than the IPPC and the Commission on Climate Change. “Because the impacts of climate change are already happening and already being felt, you can’t really put a date on it and say, ‘[do it] by then and it will be OK, because it’s already not OK. The 2030 date was a judgement on when we feel it’s feasible to implement it.”

The government is committed to net zero emissions by 2050, the Lib Dems by 2045. The feasibility or otherwise of the 2030 deadline was a point of controversy at Labour conference. The longest session of “compositing” in Labour conference history – the process by which almost 130 motions submitted by local Labour branches from around the country are mashed together into something that can be voted on by conference – resulted in not one, but two motions.

One was backed by Labour GND, with the 2030 target. The other came from the GMB union which represents many energy sector workers and couldn’t get on board with the hard deadline.

GMB General Secretary Tim Roache, meanwhile, has warned that a 2030 deadline would necessitate “a series of measures such as the confiscation of petrol cars, it will require the state rationing of meat, it will mean limiting families to one flight for every five years. And it will put entire industries and the jobs they produced in peril.” This is a bit of a downer compared to the opportunities seen by Labour GND. They propose measures like ending fuel poverty, free public transport and building green council housing.

Such arguments will need to be fought within the labour movement. Key to the Green New Deal is the concept of a “just transition” that involves workers rather than cutting jobs and workers’ rights under the cover of greenwashing.

Many are already on board. Speaking to the Labour GND rally on Brighton sea-front on Saturday, Tony Kearns from the Communication Workers Union, encouraged the audience to “make this a trade union issue” because “there’s no jobs on a dead planet”.

When it came to the voting, both the motion supported by Labour GND and GMB’s motion passed. The party leadership will presumably take both into account when it comes to the meetings that will decide on a manifesto for a forthcoming election.

Labour’s approach remains a contradiction. Shadow Chancellor John McDonnell has talked of giving Britain’s former colonies access to technology produced by Britain’s green industrial revolution as a way to pay reparations for our colonial past. Meanwhile, shadow environment minister Rebecca Long-Bailey announced a massive investment in electric cars – which would come at the cost of more destructive mining, buying into what War On Want calls “a new greenwashing narrative” that “vast quantities of metals will be needed to meet the material demands of renewable energy technologies.” This mining is threatening “frontline communities and the interconnected ecologies that sustain life and wellbeing,” but hopefully those communities will also enjoy the technology we give them.

According to Saltmarsh, the passing of the GND motion will be “an incredible piece of leverage for our movement to then exercise. We’ll be able to say, ‘you’ve committed to zero carbon by 2030, you have all these principles that means a national food service, that means free public transport, solidarity transfers of finance to the global South – all these things necessarily stem from these principles.”