In a grandiose 1930s building on the banks of the Seine in Paris, 150 French citizens chosen at random had gathered. Ranging from 16-year-old school pupils to carers, shuttle-bus drivers and retired rail workers, the French president said these ordinary people would define the next phase of his term in power.

They are part of France’s latest democratic experiment: a randomly selected citizens’ assembly that has been promised more power than any other – the ability to set Emmanuel Macron’s policy on cutting carbon emissions, as he faces harsh criticism that he is not doing enough to tackle the climate emergency.

“You took a risk in being here,” Macron told them on Friday. “But we must have this debate at the heart of society.”

In the coming months, the citizens must draw up a series of far-reaching policies on how France can cut carbon emissions by 40% before 2030. Macron has vowed their policies will then be put to parliament “unfiltered”, transformed into executive decrees or even used as the basis for a referendum. The process is being closely observed from abroad – particularly by the UK, which begins its own form of citizens’ assembly this month.

Although Macron has presented himself as a world leader on the climate emergency, France is in fact far from delivering its goals to reduce greenhouse gas emissions. Indeed, the year-long gilets jaunes (yellow vests) anti-government protests began as a crisis in climate policy. Demonstrators first took to the streets against Macron’s new carbon tax intended to urge motorists to change their behaviour. People in the countryside said it was deeply unfair to raise taxes on fuel use where there was no alternative transport to private cars. The tax was abandoned and the government has been struggling to catch up.

Macron hopes a sample of everyday French people sensitive to issues of “social justice” can do better at bringing society on board.

“This deliberation exercise wouldn’t exist if it hadn’t been for the gilets jaunes crisis,” said Mathilde Immer, who founded the Gilets Citoyens group for more citizen involvement in policy decisions, and who now sits on the climate assembly committee.

Over several months, across seven weekends, the assembly members have been briefed by experts and have deliberated on issues including fast fashion, plastics, transport and housing. “This is not a consultation asking for people’s views, we’re asking them to produce concrete, structural measures, that’s what’s original,” said Julien Blanchet, who is overseeing the process.

Macron’s party has said involving citizens could even be an answer to populism and the crisis in western democracy.

The participants themselves have said they were struck by the human element of the exercise and the sense of making a difference.

Romane, 17, a school student from a Brittany village, was in her bedroom one Sunday night last autumn when she was surprised to get a text message saying she had been randomly picked from more than 300,000 phone numbers. Her parents, a farmer and recruitment agent, encouraged her to sign up. It was crucial for organisers to include people under 18.

“Climate change is the key issue for our generation and our future,” said Romane, who wants to study management. “At my first sessions, the full sense of the climate emergency really hit me and I was a bit scared, but now I think if we give our all, we can make proposals for change.” Personally, she does what she can. “I try to use public transport, but the nearest bus stop is in the next village so I have to take a car to get there.”

Calls to ban cars might be popular among those in Paris, but do not go down well in the countryside. Photograph: Bertrand Guay/AFP via Getty Images

Grégoire Fraty, 31, who lives in Normandy, is from what geographers call the French periphery – the hinterland outside cities where gilets jaunes protesters mobilised and which is increasingly targeted by the far right. He grew up in a tower block in a Paris banlieue before moving to the country “for the clean air”, and works helping jobless people get back into employment. He liked working through different opinions to find consensus. “When a Parisian who lives right next to a metro station says, ‘Oh, we need to ban cars’, I might say, ‘Look, when you live in the countryside and have to drive your car 15km to buy bread, it’s something else’.”

He added: “If we build an efficient public transport network for 90% of French people across the country, then we can reduce cars. But surely you have to do things in the right order? You can’t put people in difficulty before finding solutions.”

He said his family used one car, not two, and he now would not take flights for a holiday. “I see myself as the silent majority: someone who does a little bit for the environment, but could do more.” He said it was about getting society on board. “We’re not inventing miracle solutions, we’re just reinventing the workings to make sure solutions will be accepted.”

Sylvain Burquier, 45, described himself as a typical “cynical Parisian advertising executive” despite spending his childhood in the Alps. “I’ve become really passionate about the human experience of putting so many different people together. We’re being asked to come up with proposals to basically save humanity, so there’s a lot resting on this! When you take 150 different people, with different complaints and incoherences and indiscipline, and then they get together to produce a work of collective intelligence, I find that remarkable and very touching.”

He said it was not just about creating policy for individuals to change their habits. “Even if we do something drastic and demand a huge effort from individuals on travel and consumption, that would only get us 25% of the way there. Companies have a huge role to play – but it doesn’t have to be a negative message of fear and collapse, there can be positive ways to encourage change.”

He said inserting new climate elements into the French constitution would be a revolutionary possibility, but there would also be concrete measures impacting people’s everyday lives. The process had reignited his interest in politics and debate. “I’ve got back some of my teenage enthusiasm.”