One of the striking features of how concern over global warming has risen to the top of our political agenda is the extraordinary unanimity with which it has been taken up by our political establishment.

Not only have our main political parties unquestioningly accepted the more extreme claims of the threat posed by global warming, as exemplified by the Treasury's Stern Review or Al Gore's alarmist film. Our politicians have similarly endorsed without a murmur all the steps now being taken to avert this predicted catastrophe - which, if carried through, can only mean a dramatic transformation in our way of life.

Only one senior political figure in Britain has dared stand apart from this stifling orthodoxy: Nigel Lawson, now Lord Lawson of Blaby, who as Margaret Thatcher's Chancellor presided over the renaissance of our economy in the 1980s.

©Andrew Crowley
Lord Lawson: the science is far from settled or understood

In 2005 Lord Lawson played an influential part in shaping a report on The Economics of Climate Change by the Lords economic affairs committee. It stood out as a measured but often critical appraisal both of the science behind orthodox global warming theory and of the political response to it.

In 2006, in a lecture to the Centre for Policy Studies, Lord Lawson gave a more personal view of one of the overriding political issues of our time, which he has now expanded into a book, An Appeal To Reason: A Cool Look At Global Warming.

His timing is impeccable. On one hand, we are just starting to appreciate the colossal cost of the measures being taken to meet the European Union's target of a 60 per cent cut in our CO2 emissions in the next four decades, ranging from plans to spend hundreds of billions of pounds on wind turbines to the EU's emissions trading scheme, already costing us billions through our electricity bills.

On the other hand, global temperatures, after flattening out, have in recent months shown a sharp fall, wholly unpredicted by those computer models on which the proponents of warming orthodoxy rely. This raises rather large question marks over whether the theory has actually got it right.

When I met Lord Lawson at the House of Lords, I hadn't seen him since his famously drastic slimming regime, some years back, left him looking rather gaunt. I was relieved to see him now, at the age of 76, looking remarkably well-preserved as he continues to divide his active life between the House of Lords, two company chairmanships and his home in south-western France.

How did he come to develop such an informed interest in this subject? "When, in 2005, I was invited to serve on the Lords committee," he explains, "I felt there was no issue more appropriate for us to look at than the economic implications of global warming, because they are so enormous, and so few people seemed to be doing it."

What was most striking about that Lords inquiry was the range of expert witnesses it called. These naturally included leading supporters of the official orthodoxy, such as Sir John Houghton, chairman of the working group of the UN's Intergovernmental Panel on Climate Change (IPCC), which since 1988 has been the central player in alerting the world to the supposed dangers of global warming.

But also invited to testify were some eminent dissenters, such as the US climatologist Professor Richard Lindzen and Paul Reiter, the world's leading expert on tropical diseases, both outspoken critics of the much-vaunted "scientific consensus" on global warming.

"Considering the differing views our committee started with," says Lord Lawson, "it was quite an achievement that we ended up unanimously agreed on what was in many ways a fairly critical report. But the key was that we based our findings on examining the evidence" - and this remains a marked feature of his book.

"Undoubtedly," he says, "the closing years of the 20th century saw a modest warming in global temperatures. But the orthodox explanation for this has a problem. While atmospheric CO2 continues to rise, temperatures have not in the past decade followed suit.

"They try to explain this," he adds mischievously, "by saying that global warming will resume in 2009 or thereabouts.
Maybe it will: we shall see."

Snow falling on a beach in Greece appears to give the lie to the apocalyptic predictions of Al Gore and others says Lord Lawson

Some of the committee's most trenchant criticism, echoed by Lord Lawson today, was reserved for the way the IPCC "has mutated in the minds of those who head it into something more like a politically correct alarmist pressure group".

"Nevertheless," he says, "we have to accept that the IPCC is far and away the most influential player on this issue. What I therefore try to do in my book is to accept the general case it has made, but to look very carefully at how it is made and its implications."

One useful thing Lord Lawson does is to examine what the IPCC is actually saying in the small print of its latest report, as compared with the wilder exaggerations favoured by the Stern Review and Al Gore. "If you look at the IPCC's detailed predictions, on such issues as food and water shortages, sea-level rise and health, they paint nothing like the catastrophe we are made familiar with by the media. A maximum sea-level rise of 23in over 100 years hardly compares with the 20ft predicted by Mr Gore's film.

"Indeed, from the IPCC's predictions," he says, "we can calculate that the upshot of this great disaster facing the world might be that our great-grandchildren, instead of being slightly more than 4.8 times as well off as we are, would be only 4.7 times as well off."

One huge gap in the IPCC's thinking, Lord Lawson suggests, is that "it fails almost completely to take account of the capacity of human beings to adapt to changing temperatures - as we can see from comparing Finland with Singapore, two of the world's most successful economies. In the first, people manage to live happily with an average annual temperature of 5C; in the second, they can cope with an average of 27C."

He goes on to contrast some of the crazier predictions on such matters as the melting of polar ice or the shifting of the Gulf Stream with the much less alarmist views of genuine experts in these fields - showing how the "threat from which the planet must be saved" has been almost laughably exaggerated.

So what then should we do about it? Lord Lawson discusses the familiar implausibility of reaching any worldwide agreement on massive cuts in CO2, when developing countries such as China and India cannot see why they should be denied the hope of emulating the living standards of the West.

He similarly dismisses the futility of most of the techniques being proposed to "mitigate" those emissions, from "cap-and-trade" schemes to reliance on biofuels, which "even the most zealous environmentalists now realise do far more environmental damage than anything they might seek to cure".

As for "such feelgood measures as driving a hybrid car or not leaving our television sets on standby, in this context they are trivial to the point of irrelevance".

"Our politicians," he says, "need to be honest with the people. If they believe that we need to cut back drastically on carbon dioxide emissions today, at considerable cost and disruption to our way of life, because there is a remote risk of major disaster some time in the distant future, they should make the case explicitly in those terms.

"The fact is," he concludes, "that the science of what determines the earth's temperature is far from settled or understood - and fortunately opinion surveys suggest that the majority of people, even in the UK where politicians of all parties sing from the same politically correct hymn sheet, instinctively sense that this is so."

Lord Lawson closes on a note that others of us have struck in trying to puzzle out the deeper reasons for this great climate panic. He recognises that in many ways the global warming ideology has filled the vacuum left by the collapse of Marxism: "Green is the new red."

He sees parallels with the apocalyptic visions held out by certain religious movements in the past. He is alarmed by the fanatical intolerance shown by many believers in global warming to any heretic who dares question their certainties.

He ends by describing "the new religion of global warming" as "the Da Vinci Code of environmentalism. It is a great story and a best-seller. It contains a grain of truth and a mountain of nonsense.

"We have entered," he says, "a new age of unreason, which threatens to be as economically harmful as it is disquieting. It is from this, above all, that we really do need to save the planet."

An Appeal to Reason: A Cool Look at Global Warming will be published on Thursday (Duckworth, ยฃ9.99)

Christopher Booker recently published Scared to Death: From BSE to Global Warming - Why Scares Are Costing Us the Earth (Continuum, ยฃ14.99)