IN 2020 it will be 30 years since the climate became politicised. It all began with the first report from the Intergovernmental Panel on Climate Change, in a series which continues. Before then, nobody thought much about global warming.

In fact, as a little lad I had an encyclopedia confidently stating that we stood at the threshold of a new Ice Age, on the grounds that one happened every 10,000 years and it was time for another.

This reasoning may seem dubious. But it is as good as any deployed by the zealots who have been besieging the UN conference on the climate crisis, which opened yesterday in New York.

From there, we hear the cry of the fanatic down the ages: “You’re doomed, all of you! The end is nigh!” But the atmospheric clock moves rather more slowly than any anthropoid clock down here on the surface of planet Earth, simply because the atmosphere is so complex and subject to many different influences.

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I can name three episodes in my own lifetime which seemed, and were held, to mark a definite turning point for the climate. One was a cold spell in the mid-1990s when I recall watching the River Clyde freeze over below the Kingston Bridge. Then the Noughties took off on a different tack, settled and mild: no snow in central Scotland for 10 years. Third came the apparent descent into chaos we are living through now, with swings from one extreme to the other, heatwave followed by hurricane. Perhaps the youthful radicals have just not lived long enough to see that climate changes all the time: it’s called weather.

The National: The River Clyde froze under the Kingston Bridge in the 1990sThe River Clyde froze under the Kingston Bridge in the 1990s

In fact I’m more worried by a far longer-lasting trait of human nature, the deep urge in some people to criticise and control the behaviour of others. It needs trendy pretexts rather than objective causes, and it also goes in cycles, perhaps accelerating cycles. The 17th century was puritanical and the 18th century licentious. Victorians were prudish and Edwardians promiscuous. After the Second World War people were sexually repressed but by the 1960s they were sexually liberated. Now we’re going through another abstemious phase.

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Various instruments of enforcement have been tried down the ages, from burning at the stake to the ration book. This time round we prefer the political ban, and here the Scottish Government is a world leader. In a previous column I’ve written about the burden of regulation that is being placed on some patriotic scientists who want to exploit marine biology for our independent nation to develop industries of the future.

The burden has become so impossible that they have decided to move somewhere else, and Scotland’s loss will be Iceland’s gain. Expect more of such examples.

Since the Scottish Government rests on the view that it is in principle omnipotent, there can be no end to the bans that might be imposed. All it needs do is frame a law or a regulation and – hey presto! – another political victory. With faith in markets fading, it is easy for politicians to manipulate subsidies and prices so that, for example, windfarms are saved from the economic disadvantage they suffer in comparison with fossil fuels. We can just ignore that this makes all our energy more expensive, makes all our industry less competitive and makes all our consumers worse off. At least we can rant on about the curse of poverty in our society.

The National: Wind power is more expensive than fossil fuelsWind power is more expensive than fossil fuels

At the same time we hear little of the fact that the green agenda can cause environmental problems of its own, such as the pollution produced by the switch to diesel cars or the strain on scarce land from the growing of biofuels, with energy produced from plants. The climate zealots slide past these contradictions. The morality play must go on.

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It has become almost useless to raise objections to the narrative of doom. For instance, the journal Nature recently reported that the world’s tree cover has actually risen by 7% since 1982. Or again, the UN’s Food and Agriculture Organisation forecasts that global production of meat will have doubled by 2050, so that the efforts of green activists to turn us all vegan are really a waste of time.

One basic reason is that the world in its efforts to achieve growth, or when necessary to reverse recession, has since 1999 doubled its living standards, as measured by gross domestic product. Many developed countries, including the UK, have suffered spells of stagnation, so the main impetus must have come from former poor countries.

Once upon a time most Chinese and Indians could only dream of eating meat, but now they are catching up. As I said last week, look at the Japanese rugby team. As for the Brazilians, they ask why it was all right for Europe to burn its forests 1000 years ago and start on its long agricultural progress, while it is wrong for them to follow now.

These former poor countries have grown to be materialist rather than idealist in their outlook: it is only the rich who have time and leisure for idealism.

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But now the traditionally vegetarian peoples want the pleasures (and health benefits) of a kind long enjoyed by carnivore westerners. Many of them resent westerners, however. They will resent us all the more if we lecture them that our new-found love of the planet should still dictate their choices in real life.

I suppose the climate zealots only ask of them what they demand of us. Environmental convictions are becoming a religion, the best means since the decline of Christianity to make people feel they are bad or good. Those who ask questions whether forecasts of climate change are accurate, or who raise doubts about the value of government control as opposed to freedom of technological development, should not even be spoken to by those who recycle everything and never eat steak.

The National: Climate protesters want everyone to unite against climate changeClimate protesters want everyone to unite against climate change

Westerners used to worry about celestial salvation, then about earthly things, such as sex. Food seems likely to become the next weapon in the eternal crusade to purify us from the sins of ordinary, innocent everyday life, from our prosperity and our pleasures. It is a good target to choose because, as religious fanatics have always understood, people can easily be made to feel guilty about food, about pork in the case of Muslims, about beef in the case of Hindus.

Donning my prophetic robe and turban, I see a culture war coming. Steakhouses will be picketed. Planning permission for supermarkets selling meat will crash against objections. Schoolchildren from carnivore homes will be sent for re-education. The General Assembly of the Kirk, the National Trust for Scotland and the University of Glasgow will agree to stop raising cows and sheep on all their land holdings. Nobody will be allowed to serve on quangos who pollutes their digestive system with red meat. Jesus will no longer be the Good Shepherd, since the phrase will be seen as a contradiction in terms. Who knows?

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Maybe one day Maggie Thatcher the Milk-snatcher will be hailed as a heroine who kept planet-destroying swill out of the mouths of babes and sucklings.

The planet will actually derive no benefit at all, of course, but the Greens will feel righteous and taunt the rest of us for being dirty. Which is the purpose of the exercise.