Suddenly global warming has come in from the cold. A potent combination of startling natural events, growing public pressure, and pioneering political commitments has brought it storming up the agenda.

Even many of the previously sceptical are now convinced. For example, who would have thought the leader of the Conservative Party would become Britain's most potent champion of radical action to combat climate change, or that he would share platforms with the leader of Friends of the Earth?

And who would have imagined Arnold Schwarzenegger - famous as for his devotion to the Humvee, the greatest of the gas guzzlers - would defy his party, as Governor of California, to drive through the world's most ambitious programme for cutting the pollution that causes global warming?

And as we report (right), even the "Toxic Texan" himself - President George W Bush, who set out to kill the Kyoto Protocol and all international attempts to tackle the problem - is laying the ground for a U-turn.

These dramatic changes of heart are not happening among scientists. There has long been more unanimity in the scientific community about the reality of global warming than over any other environmental issue I have known; a recent survey of 928 scientific papers found not a single one that dissented.

Nor are they occurring in public opinion, which is becoming steadily more convinced, and alarmed - even in the United States. A recent CBS/New York Times poll shows that four in every five Americans (including three out of every five Republicans) believe it is a serious, or very serious, threat - and that three-quarters of Americans (and more than half of Republicans) insist that action must be taken to counter it "right away."

No, it has been the political and media establishments that have lagged behind, both here and in the United States. A survey of US media articles, in contrast with the one on scientific papers, found a majority cast doubt on the reality of global warming. Even here, climate change sceptics are two a penny in Islington, if almost impossible to find in the laboratory.

Though Tony Blair has made much of his praiseworthy achievement in putting the issue at the top of the agenda of last year's G8 summit, emissions of carbon dioxide have actually risen since Labour came to power. But now the born-again conversions are coming faster than at a revivalist rally.

Last week The Economist - bible of businessmen and right-of-centre politicians on both sides of the Atlantic - abandoned years of lordly scepticism to call on President Bush to lead the way in taking action.

And on Friday, Gerard Baker - a columnist on The Times much admired by Rupert Murdoch - confessing his own scepticism, concluded, "the only prudent course is to act now to reduce emissions...". The old man's youngest son, James, chief executive of BSkyB, is already on board, pressing for change like an old green campaigner.

And talking of conversions, how about this? An alliance of US Envangelical Christians - God gave humanity dominion to exploit nature as it wished - is calling for action in climate change as "a moral and spiritual issue". The catalyst for much of this is an unlikely box-office success, with an even less likely star. An Inconvenient Truth, fronted by former vice-president Al Gore, which was released in Britain on Friday, has already become the third most-seen documentary in US film history; it has even overtaken Truth or Dare (aka In Bed With Madonna).

So far, some 2.3 million Americans have gone to see a two-hour illustrated lecture by a man with a reputation as one of the most wooden politicians ever to run for public office.

Most have been blown away. Partly by Gore, who is warm, human, witty, at times moving, and who gives the best explanation of the issue I have seen. Partly by some spectacular photography and some stunning graphics. But mostly by the compelling evidence he presents.

Gore worries why politicians and governments have been so slow. Such was his "faith in the democratic system", he says, that he thought the mere emergence of the facts would be enough to spark a "sea-change in Congress.

He comes to a somewhat charitable conclusion: "If an issue is not on the tip of their constituents' tongues it is easy for them to ignore it". But there is a hole at heart of the argument, a huge opportunity missed, for Gore tells us nothing of his failure when he himself was in power.

He tells us how he was one of the first people to become concerned about global warming, as a university student taught by one of the scientists who first identified what was happening. And he recounts how he held Congressional hearings on the issue and ran for President partly to highlight it.

But he glosses over his own time in office, when he was put in charge of environmental policy by President Clinton. Even then, the US dragged its feet in the climate negotiations. Worse, its carbon dioxide emissions shot up far faster than at any time in modern history - by 15 per cent, compared to just 1.65 per cent during the Toxic Texan's first term.

If Gore had stuck to his principles, however, he would almost certainly now have been President; Ralph Nader would not - and could not - have run against him on a green ticket, so denying him Florida.

His friends say that he has figured this out, and he has certainly worked his penance - trudging round the country to give the lecture now featured in the film at least a thousand times.

But it is important that he comes clean. Not just for the cause of truth he espouses, but because a new generation of politicians - including David Cameron - are making the issue their own. Who better to teach them about the difficulties they may face in office, and about the costs - both to themselves and the world - of failing to implement their beliefs?

© Copyright 2006 Independent News and Media Limited

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