If you’ve seen the YouTube video of Ruben Östlund’s reaction when his latest film wasn’t nominated for a Best Foreign Film Oscar, you’ll go some way towards understanding the offbeat humour of said film, Force Majeure.

In the video, the Swedish director and his producer Erik Hemmendorff film themselves watching the live nominations: when they miss out, Östlund wanders off-screen – all we hear is a loud, inhuman cry and Hemmendorff beseeching him, ‘don’t undress’.

‘A lot of people have asked me if it’s fake,’ laughs Östlund when we chat at The Hospital Club in London’s Covent Garden. ‘And, errr, I won’t tell.’

Set in a ski resort in the Alps, Force Majeure pivots around a single, split-second reaction. Tomas (Johannes Kuhnke), Ebba (Lisa Loven Kongsli) and their two children are enjoying a family skiing holiday; as they eat at an outdoor terrace restaurant, a controlled avalanche looks like it’s coming too close. Ebba grabs her children and shelters them – Tomas, meanwhile, grabs his mobile phone and runs away.

‘I saw a YouTube clip of a group of tourists sitting in an outdoor restaurant high up in the mountains and watching an avalanche tumbling down a mountainside,’ explains Östlund. ‘I reconstructed [the scene] the same way as the clip. In the beginning, they’re like, ‘Wow, beautiful’. And then it gets bigger and in three seconds it goes from joyful to nervous laughter to screaming to panic. Like in the clip, it’s only the snow smoke that reaches the restaurant. The guests have to go back to their seats afterwards and they’re a little bit ashamed of their behaviour.’

In Force Majeure, Tomas wanders back and makes light of the incident; for Ebba, their holiday is ruined. What follows is a rivetingly humorous, sometimes painful, look at how it affects their relationship, their kids and even their friends (Fanni Metelius and Game of Thrones’ Kristofer Hivju put in a great show as their friends, Fanni and Mats).

For Östlund, it’s all about showing how human beings buck against expectations when they’re in perilous situations.

‘There’s an Iranian saying a journalist told me,’ he says. ‘It’s: “when the water is reaching the mother’s nose, the baby is being put under the feet”. This is who we are and what we are able to do. We think we don’t have to deal with situations like that as we are living safe and secure lives. So we think, of course I will save my children first, because we have no knowledge about what happens [in those situations].’

‘I was also inspired by the captain of the Concordia,’ he adds, talking about the cruise ship that capsized and sank in 2012; its captain – later dubbed ‘Captain Coward’ – made a hasty departure from the ship before many of the other passengers. ‘He started this silly lie that he fell into the lifeboat. There was something about shame, something about losing identity as a human being that is very, very painful. Sometimes we’d rather die than lose our identity.’

While Tomas spends most of the film trying to downplay his speedy exit, he snaps near the end – it’s the catalyst for Force Majeure’s most memorable scene, in which Tomas breaks down in heaving, pathetic sobs. It’s probably the most unsympathetic crying scene ever put on film, and it’s the one that Östlund is (probably) parodying in his Oscar video. When shooting it, he took his cues from – you guessed it – YouTube.

‘I always look for references on YouTube,’ he says. ‘So if I have a scene like this, I google worst man cry and see what kind of worst man cry is up on YouTube. I get a lot of inspiration on YouTube. I use it almost like a working method. Rather than looking at cinema history, I ask what moving images do we currently have of similar situations.’

For the director, the setting of a ski resort is the ideal place to explore this total breakdown of control. ‘It’s such a kitschy world, with all those neon colours and mirror goggle lenses,’ explains Östlund, who started out making skiing films before he went to film school.

‘I think the ski resort almost becomes a metaphor for what’s happening in the family. There’s a constant struggle of trying to control nature, by grooming tracks in the snow with snowcats, blowing avalanches to control their power, putting up avalanche fences. It’s a constant struggle between civilisation and the uncivilised forces of nature. In the same way that Tomas, he wants to control his uncivilised side with a civilised façade.’

It’s beautifully filmed, and Östlund wrings out every last drop of tension and humour from the situation. Its lack of an Oscar nomination is certainly unjust, but that hasn’t kept people from watching – and loving – the film. VEEP’s Julia Louis-Dreyfus is even in talks to produce and star in an American remake.

‘A lot of people are asking me if they get divorced when they get home,’ Östlund says. Then he laughs: ‘I say, if it’s a happy film, then yes they do get divorced. If it’s an unhappy film, they will stay together until death separates them!’

Force Majeure is on general release from Fri 10 Apr, read our review from GFF.