In the Mall, up Whitehall, or crossing Trafalgar Square early this morning, the climate activists looked like rush-hour office workers and civil servants – mainly 30 to 50-year-olds, with no dreadlocked tree-huggers, SWP banners or black-masked anarchists looking for a punch-up. Chanting about the climate emergency, frankly, they seemed a bit sheepish, not used to it. Their ordinariness makes Extinction Rebellion, or XR, especially effective: farmers, scientists, doctors, Cumbrians and other local platoons stand at the 12 key roadblocks.

After their successful capture of central London in April, local cells or “affinity groups” all over the country have trained and planned for this protest. Deciding who would be “arrestable” for highway obstruction – and who wouldn’t be, because of jobs or young families – they were primed to expect a tougher police response after rightwing press complaints against the friendly policing last April, when officers were caught dancing at a blocked Oxford Circus.

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“I do wonder if protest makes a difference,” an office manager in her 40s from Hertfordshire said to me. “But what else can you do? My children really made me feel I must.” A steward in a pink gilet, a mother from south London, said the same: “It was my children who got me into this.” Thousands more are expected to join.

For those who doubt the effect of last April’s XR protests, Ben Page of Ipsos Mori says: “In our polls in 2013, 59% said the planet was ‘heading for disaster’. This year it’s gone up to 78%.” He reckons Greta Thunberg, the school strikes and XR action played their part. What packs an extra punch is that London is just one of 60 global cities engaged in “uprising” at the same time. To those who say why bother, when the UK is too small for our carbon emissions to matter, this synchronised global action reaches all those leaders who attended last month’s UN climate change summit – where the UN general secretary warned: “We face a direct existential threat.”

I think few of these protesters read the rightwing press to know what they’re up against. In a double-page spread in the Mail on Sunday, Douglas Murray, Spectator associate editor and author of Neoconservatism: Why We Need it, launched a blistering attack on climate protesters and soft policing tactics. He writes: “Their refusal to acknowledge any view but their own deranged belief and their defiance of democratic norms is authoritarian, even fascistic … Despite the childish certainty these extremists promote, the science of climate change is deeply contested. Most scientists agree there are variations going on but they disagree on exactly what causes it.”

Play Video 2:00 'We have the right to rebel': Extinction Rebellion begin Westminster shutdown – video

So that’s where the climate deniers are now, ignoring Nasa’s survey showing 97% of global climate scientists agree that the five warmest years have been the past five, “extremely likely due to human activities”. Never mind the science: what free-market obsessives like Murray can’t bear is that solving the climate crisis requires state and international action. He would rather boil to oblivion, faithful to his free-market creed, than see the planet saved by means he regards as statist or even socialist. “Anarchists” and “warmed-over communists” demanding “draconian solutions”, he calls the protesters. His disgust spews out at Thunberg, “this privileged young girl … hectoring others on things she barely understands … delivering unhinged sermons to the credulous global elites”. Among the deadly weapons used against activists is that too many are middle class, and they are all climate hypocrites. Progressives are prone to self-flagellation, but being climate-pure is impossible. Do what you can, cast off the guilt. Murray’s is the blind rage of the losing side. David Attenborough is believed, not the Mail on Sunday. Even delivery drivers angry at the roadblocks weren’t denying the gravity of the cause. Weekly the news tells of sea ice and glaciers melting, species vanishing, the emergency evident: pollsters find people well understand it and trust the scientists who say humans are the cause.

Murray accuses XR of wanting to “engineer the complete destruction of the global economic system”. But this highly democratic group is carefully nonprescriptive. All they ask is for politicians to accept the emergency, for a much tighter target than 2050 for net-zero carbon (the UK is already badly behind, our statutory Committee on Climate Change says) – and for a citizens assembly, such as President Macron has just set up with a sample group of 150 citizens to advise on how France can cut carbon emissions. That’s the task: finding solutions people will vote for.

At the party conferences, the Tories barely mentioned climate, while Boris Johnson talks of fuel tax cuts. But Labour puts a green industrial strategy at the heart of its spending plans, building renewables in wind and solar, solar panels and insulation for a million social homes, £3.6bn on charging points and free loans for electric cars, nationalising the grid for a vast expansion of 37 offshore wind farms, tidal energy from Swansea Bay and no fracking.

The UK may be entering a climate culture change that Page compares to the shift in our lifetimes from locking up gay people to a recent poll that found 66% would have no concerns about a same-sex marriage in the royal family. Flying, driving, eating beef may go the way of smoking – but only if the heavy lifting is done by the state.

• Polly Toynbee is a Guardian columnist