I HATE to be the person who breaks it to everyone, especially at this late stage, but Brexit and Scottish independence don’t really matter that much – or rather they matter, but in the way that a fiddle matters to a burning Rome. The burning imagery is fitting because what really matters is the torching of the Earth by the human race.

I am taking it for granted that readers believe in climate change – know for a fact that it’s real – and so I’m not going to rehearse the science, which has been long established and proven. If anyone doubts the truth of climate change, the queue to join the Flat Earth Society is just over there.

If you believe in climate change then you should fear it – and I don’t just mean worry about it when you hear the words on the news, I mean dread it, be terrified by it on an existential level, or perhaps a mass extinction level. If you don’t– if you sit and fret about Brexit or Scottish independence more than you do the planet’s rising temperature -–then you may as well be worrying about your mortgage repayments while there’s a killer in your house with a gun at your child’s head.

More and more people are getting this: that the only really important question facing the human race is how we ensure that the planet survives so our children and grandchildren can grow old, live well and be happy. At the weekend in London, thousands of demonstrators carried out one of the biggest acts of mass civil disobedience in the UK in decades in an attempt to hammer into the thick skulls of our political leaders that climate change matters above all else. It got little news coverage.

Around 85 people were arrested after blocking London’s main bridges. The demonstrators – part of the new organisation Extinction Rebellion – will continue the disruption tomorrow, when activists will converge on central London. I wish they were doing the same in Glasgow or Edinburgh, because I quite fancy handcuffing myself to some railings with them.

The basis of their anger and fear is not only sound and incontrovertible, but morally just. Each one of us should be acting, or at least speaking up. In October, the UN Intergovernmental Panel on Climate Change (IPCC) said there are now just 12 years to avert planetary disaster. Twelve years – cosmologically that’s the blink of an eye. Twelve years ago, Tony Blair was Prime Minister. Menzies Campbell replaced Charles Kennedy as LibDem leader. Daniel Craig debuted as Bond. Oh, and Europe was hit by a heatwave giving the UK its hottest July on record. The shape of things to come, eh?

Did you hear much about that IPCC report? Did newspapers clear 12 pages to give you every spit and cough of the findings? Did the TV news run extended reports? Did Parliament – any parliament – go into special session? We have a dozen years – until 2030 – in which to keep global warming to a maximum of 1.5C. If we go even a half a degree above that then drought, floods and heatwaves will mean death and poverty for millions. Coral reefs could be completely eradicated.

Read more: Climate change activists block London bridges

With the world now 1C warmer than pre-industrial levels, the IPCC made clear that the hurricanes, droughts and forest fires we are seeing around the world is climate change happening before our very eyes. There have even been forest fires in Lapland in the Artic circle. At 1.5C the proportion of the world’s population exposed to water shortages would be 50 per cent lower than at 2C. Food would not become as scarce with a 1.5C rise than with a 2C rise. Hundreds of millions more people will be thrust into poverty with a 2C rise than a 1.5C rise. Heat-related deaths would also increase, insects would lose half their natural habitat, sea-level rise would affect 10 million more people, marine fisheries would crash. At current rates, though, the world is possibly headed for 3C worth of warming.

Almost 100 senior British academics back Extinction Rebellion’s campaign of civil disobedience, and the former Archbishop of Canterbury Rowan Williams has thrown his hat into the ring with them as well. These experts say that the failure of politicians to tackle climate change has broken the “social contract” between government and the people. In an open letter they said it was their right to “bypass the Government’s inaction and flagrant dereliction of duty and to rebel to defend life itself”.

We live in the era of the short attention span – news cycles come in a blizzard, stories swirl and dissipate with the wind before they are properly told – and climate change is a slow-moving catastrophe. It is hard to see – it requires reading, thought and consideration. Climate change does not appear on TV with silly blond hair spouting about the return of £350 million from the EU to the NHS; climate change does not endlessly bicker about independence; climate change does not cause a punch-up on Twitter over trans rights or someone dressed as Hitler.

Who cares about whether we are in or out of Europe if the world is starting to burn? What is Scottish independence worth if no-one is putting the fire out? Why should I worry about what anyone on social media says if the people typing away will be lucky to be alive in 12 years’ time? Perhaps, the only national or international story that really matters apart from climate change is Donald Trump – as his policies, his fetishisation of coal and dirty industries, compounds global warming.

Many have described events such as Brexit as “suicidal” or “an act of national self-harm”. Weighed in the balance against climate change, it is the equivalent of comparing stubbing your toe to slitting your own throat.

The climate rebels want a few simple things – a commitment by the Government to reduce carbon emissions to zero by 2025 and a “citizens assembly” to devise an emergency plan of action similar to that seen during the Second World War. As one young woman who attended the London demo, named Alice, said: “This moment will be remembered in the history books, when we finally stopped allowing our leaders to take us over a cliff.” Pray she is right.