[PARIS] When the French actress Melanie Laurent read a now famous 2012 paper by leading scientists warning that the Earth's climate was reaching a tipping point from which it may never recover, she sat down and wept.
"I was pregnant, and I was so shocked I spent the whole day crying," she said, wondering what kind of world she was bringing her child into.
But instead of succumbing to fatalism, Laurent - best known for her role in Quentin Tarantino's Inglourious Basterds - went looking for the positive.
With study after study confirming the dire warnings by experts about the state of the biosphere, Laurent and her friend Cyril Dion felt people needed hope.
Demain (Tomorrow), their feelgood film about how the world can change for the better - and the inspirational farm, energy and educational pioneers who are pointing the way - has had cinema audiences on their feet.
More than a million people have so far flocked to see it in France alone, where it won the Cesar - or "French Oscar" - for the best documentary of the year.
The film shows how new French peramculture techniques can make small organic microfarms 10 times more productive than industrial farming - and all without the aid of a single piece of petrol-driven machinery.
It highlights how major cities like San Francisco are recycling and composting 80 per cent of domestic waste - and making money from it - while Copenhagen aims to run on renewable energy alone within less than a decade.
The US city of Detroit hopes to feed half its population from its booming urban vegetable plots in a country where food travels on average of 2,400 kilometres (1,500 miles) between farm and plate.
Mr Dion, an environmentalist, said he was overawed by the enthusiasm that has greeted the crowd-funded film in France, Belgium and Switzerland, receiving standing ovations wherever it showed.
"People say that it has given them back hope and enthusiasm to do lots of things... that things can be done," he said.
Many see it as a turning point in the way environmental issues are seen, with the film also raising questions about whether democratic systems need to be rethought to hold energy and industrial interests to account.
"A day doesn't go by without someone talking to me about this film," Txetx Etcheverry, of the European ecological network Alternatiba told AFP. "Mostly it is people who are not convinced ecologists, and they are urging their families and their friends to go see it."
Philosopher Dominique Bourg, from the University of Lausanne in Switzerland, said the film was a breath of fresh air, a counterblast of "good ideas" against a tide of received wisdom and cynicism.
"While the elites are always telling us there is no alternative, at several levels the film gives examples of how there are other ways of living and doing things in agriculture, in industry and in government," he added.
"It taps into people's need to take their destinies in their hands and live in other, better ways," Mr Bourg told AFP.
And the message appears to be getting through. Users of the France's top film website have given Demain the highest rating of any documentary in its 13-year history.
While other documentaries - notably former US vice-president Al Gore's An Inconvenient Truth about global warming - have brought green issues to the multiplexes, none have been as relentlessly upbeat as Demain.
It hails participative democracy and local currency schemes as ways of protecting communities from the worst excesses of the global capitalism.
Mr Dion said the idea was to draw attention to some of the best projects and show what a huge difference they could make if they were rolled out across the planet.
"It is not at all an environmental film in the cliched sense of the term, Mr Dion told AFP. "It's a film about how we live and so in that sense it is an ecological, because for things to work well in a ecosystem they have to work in harmony."