I’ve just glimpsed the future and I think we’re all doomed: thousands and thousands of kids, bunking off school with their parents’ and teachers’ encouragement, in order to pay homage to an eco-fascist demagogue in a bright yellow sou’wester and to march for less prosperity, less freedom and more misery.

I’m talking, of course, about the Bristol Youth Strike 4 Climate, a rally starring Greta Thunberg in Britain’s greenest city, which I attended along with an estimated 30,000 children, protesting about ‘muh climate change’, or something.

The weather was awful – Mother Gaia had forgotten to get the global warming memo – and in the rain and cold the green space, College Green, where the rally was held was quickly reduced to a slippery (and not very eco-) brown sludge.

But the most dispiriting part was seeing so many kids misdirecting their youthful energy and passion and zeal so horribly. They could have been in school learning something useful; they could have been on a sports field playing games and getting fit and healthy; they could have been curled up at home with a book – or playing Fortnite, even that would have been a better use of their time than this…

Instead, here they all were, gazing rapturously like acolytes of some millennial doom cult at the podium where their dear leader, St Greta of Thunberg, was intoning the usual mantras about imminent climate doom.

‘I will not stand aside and watch. I will not be silenced while the world is on fire. Will you?’ she said, in that intense, charmless, dogmatic way of hers which, bizarrely, her fans find captivating. ‘No,’ the crowd roared back.

(On the way to the rally, I heard several children mimicking Greta’s trademark ‘How dare you!’ phrase and expressing the hope that she’d use it on stage – a bit like wanting Led Zep to do Stairway to Heaven, I suppose.)

Greta was preceded on stage by several other young female eco-activists, one of them especially screechy and whiny and shrill. One of the tragedies of the modern age is that instead of discouraging 16 and 17-year old girls from being screechy and whiny and shrill – because it’s boring and unattractive – we have encouraged them in the idea that it’s an expression of empowerment and that when they vent their half-baked ideas about how to save the planet we should listen carefully, rather than saying: ‘Don’t you think it’s about time you got yourself a boyfriend?’ This is a mistake which we will come to rue horribly.

Many of the children were carrying signs bearing messages of doom and gloom.

One sign said: ‘You’ll die of old age. I’ll die of climate change.’ A reporter described this in a news article as ‘poignant.’

No. It’s not remotely poignant. It would only be poignant if it were genuinely the case that – in line with Greta’s predictions – the planet really were going to die of global warming in about twelve years’ time.

But the planet is not going to die of global warming in twelve years’ time. It will still be here in 120 years time, in 12,000 years time and more likely than not, 12 million years time. To pretend otherwise, to give credence to the scrawl that some brainwashed child has written on a placard, to endorse it by affecting to be moved by it, is precisely how we’ve ended up so deep in this mess.

We’re in this mess because the adults have left the room.

‘Politicians are behaving like children,’ said Greta at one point – and she was absolutely right, though for completely the wrong reasons.

Britain’s Net-Zero climate policy is a case in point. Without any credible cost plan, on the basis of no scientific evidence save a few dodgy computer models, to the dismay and bemusement of perhaps the majority of people who voted for him, ‘Conservative’ Prime Minister Boris Johnson has decided to decarbonise the UK economy by the arbitrary date of 2050. This will entail the kind of unnecessary expense (estimated at £3 trillion), intrusion and immiseration more usually associated with communist regimes: no more petrol or diesel cars; a ban on gas cookers, gas boilers and coal fires; yet more bat-chomping, bird-slicing eco-crucifixes blighting every view; and dramatically higher electricity prices. There’s even talk of rationing – or banning air travel.

No mature, responsible government would behave in this way. Sure it’s the sort of thing the Aztecs might have considered reasonable: making huge sacrifices to appease the sun god. But in the 21st century, civilised democracies are supposed to base their policies on cost benefit analysis, not on faddish groupthink or an urge to get down with the kids or a craven desire to appease a noisy but unrepresentative mob of eco-loons like the one that Trinity College Cambridge recently allowed to dig up its front lawn.

Speaking to some of people at the rally – I’d cunningly disguised myself with a woolly hat, anorak and Socialist Worker placard – I realised that none had a clue what the point of it all was. I asked a woman dressed as a narwhal how many narwhals she thought were going to die of climate change. ‘Try zero,’ I suggested. An earnest student type berated me for my scepticism. ‘Try going to Bangladesh!’ he said, as if that would prove anything.

But of course it wouldn’t. Bangladesh is a low-lying country prone to flooding, as it has been for millennia. This unhappy geographical accident – see also, low-lying Pacific atolls – has been exploited by the unscrupulous lobbyists for the Climate Industrial Complex to imply that it is now under some kind of unique, man-made peril it has never experienced before. Like polar bears, melting glaciers, dwindling ice caps, it has become a slogan – a mantra to be chanted by well-meaning pillocks at climate rallies in lieu of actual evidence.

I asked a young teenager who’d just told me the world was about to end if she thought she’d live to become a grandmother. ‘Oh I hope so!’ she said, cheerily. Believing two contradictory things at once is called cognitive dissonance. But it’s unlikely she’ll ever learn that phrase: not if she and her parents and teachers keep encouraging her to skip classes and go on silly climate rallies instead.

There is a solution to the most dire predictions of environmentalists, but it highlights the irrationalism of the environmental movement. Nuclear power is the obvious answer to climate change. Environmentalists’ attitude to nuclear power is like a dying man who refuses the medicine that will cure him because it has side effects. Or a woman who takes essential oils to cure cancer. It’s the logic of the person you inch away from on the train. They may have good intentions, they may be decent, but you know they’re playing in a different key to the rest of the band.

Imagine the worst-case scenario of climate-change doom. Now imagine, as an alternative, the dreadful scenario, at least that depicted by decades of environmental activism, of dozens of Fukushimas around the world. In other words, compare the relative awfulness of the two extreme cases of environmental disaster. In one scenario we all die from the effects of climate change. In the other scenario, human beings die from radiation. These are the alternatives that environmental propaganda would have us believe are facing humankind unless we magically return to a prelapsarian Eden before industrialisation. But it is a false choice. Nuclear power is safe. Chernobyl, the worst nuclear disaster of all time, was caused by what is now obsolete technology. Comparing current nuclear technology with Chernobyl is like comparing a Spitfire to a stealth bomber. They’re both airplanes but there the comparison ends.

If we are serious about climate change, and if there is a tipping point at which it is too late to reverse the terrible putative effects of global warming, then it is imperative that we build as many nuclear power stations around the world as possible – and in the shortest time frame. Warning of the apocalypse but rejecting the one approach that will mitigate its dreadful effects is the quintessence of irrationalism. It’s also a perfect description of sadomasochism. Either the threat of global warming is of monumental proportions or it’s not. You can’t have it both ways.