In April, Farhana Yamin, a 53-year-old lawyer, charged through a police cordon and super-glued her hands to the ground outside Shell’s London headquarters. A photograph shows her awkwardly straddling the concrete, peering at police officers. “Making new laws is really important. But breaking the law has become more important,” she told a reporter. Though Yamin hasn’t been charged for criminal damage, police say they may yet act against her and other Extinction Rebellion activists.

“It does seem a hugely disproportionate waste of time and, to be honest, I’ve got better things to do,” she says when we meet in Westminster for lunch. Yamin is a likeable, candid speaker who explains her decision to realign her life so dramatically “in accordance with climate science”.

Until 2017, Yamin was a visiting professor at University College London (UCL) where she taught environmental law – a position she was poised to renew until she slid into depression. “Part of it was [caused by] frustration – thinking, why am I at UCL, a university that is still accepting lots of fossil fuel money across the board?” (UCL invests over £12.2m in the industry, according to Go Fossil Free.) This, and the government’s slow pace in enacting climate legislation, impelled Yamin to join Extinction Rebellion, an international movement protesting climate breakdown that was launched in October 2018 by British activists Roger Hallam, Gail Bradbrook and Simon Bramwell.

When Extinction Rebellion blockaded central London in April, it seemed to many observers to have come from nowhere. Protesters bearing bright flags placed a fuchsia boat in the centre of Oxford Circus and staged yoga sessions on Waterloo Bridge. Once you recognised the XR logo, a bold graphic reminiscent of the CND peace design, you started to see it everywhere, on street furniture and graffiti across the capital. XR has published a book of essays with Penguin, This is Not a Drill, to which Yamin contributed an essay. It’s a slim, energetic bright-pink manual for would-be rebels.

Environmental movements have often failed to translate fleeting protests into enduring gains. In the 1980s, a split between “fundis” and “realos” in the German Green party captured this problem. “Fundis”, or fundamentalists, were speciously categorised as Birkenstock-clad, at-home-fermenting hippies who would rather stay pure than take power. “Realos”, or realists, advocated a pact with the social democrats in Gerhard Schröder’s red-green coalition.

So far, Extinction Rebellion has had real-world effects: parliament has met two of the movement’s three central demands, declaring a climate emergency and pledging to hold a citizens’ assembly on the climate emergency this autumn. But XR has framed climate change as a moral rather than political issue. Does it see all political parties as one and the same?

“This is not just a ‘wait for Labour to get in and fix it’ problem; the biodiversity crisis, extraction and destruction of nature has happened on everyone’s watch,” Yamin says. Though a Labour member, she voted Green in recent elections.

As an environmental lawyer, she helped negotiate the 2015 Paris Agreement and represented a coalition of small island nations threatened by global warming at the 2009 Copenhagen climate conference. This coalition’s insistence that policymakers focus on the risks presented by 1.5 degrees of global warming preceded the groundbreaking 2018 report from the Intergovernmental Panel on Climate Change, which warned that anything more than 1.5 degrees of global warming could devastate life on Earth.

Despite the gravity of the report, climate activists still mistakenly believed “truth will speak to power, and power will respond”, Yamin says. Science is no longer able to exist in an apolitical vacuum. “Action – much more action – was needed,” Yamin says, thumping her fists on the table.

By its own account, Extinction Rebellion’s tactic of inviting mass arrests has been a success: 1,100 activists were arrested in London by May. Yet many have argued the strategy is tone deaf to the inequalities of the UK’s justice system. For a middle-class white activist, arrest means something different than it does for a working-class black male, for example.

“I think some of those criticisms are really well grounded,” Yamin says. “When I got arrested, at the same time I was being checked in and was being treated very kindly by police officers, a black gentleman was filing a complaint for being called a n****r. I witnessed first hand how our justice system is still full of racism.”

Yet the controversy that threatens the movement comes from within. In May, XR drew up plans (which have since been postponed) to use drones to shut down Heathrow Airport.

The charge for occupying bridges is aggravated trespass, but obstructing a plane could be a terrorism-related offence, carrying a life sentence. “The whole world is watching us – we shouldn’t be pissing about with drones,” Yamin says.

Will Extinction Rebellion move beyond these internecine disputes? “The support and desire to go forward is there – whether the brand of Extinction Rebellion survives, and what it decides to do with itself, is a different set of questions.”