KEY POINTS:
At 75, Lord Lawson could be enjoying a relaxed retirement.
Instead he is busy advocating the unpopular view that learning to live with global warming would be a more cost-effective response than trying to prevent it.
It is a cause that brought him to Auckland to deliver the Business Roundtable's Sir Ron Trotter lecture: A cool look at global warming.
"I got involved in this for two reasons. It is a fascinating subject and when I find what in my view is a great deal of nonsense and irrationality in popular and political discourse, I feel moved to speak out - particularly because I can afford to do so," he said.
"It is very difficult for someone of a younger generation if they have 'heretical' views on the subject to speak out about it because it will damage their career. That's true of scientists or politicians."
His career behind him, Lawson does not suffer that constraint.
His other reason is economic, unsurprising in someone who was Chancellor of the Exchequer for six years in Margaret Thatcher's Government.
He regards globalisation as a major force for good in the world and believes there is a danger that concerns about climate change will be exploited by latent forces of protectionism.
"Protectionist voices are always there. You hear them in Europe you hear them in the US very strongly."
China and India have made it clear their overriding priority is rapid economic growth.
"It is now their turn to achieve prosperity, as the West has before them, through cheap carbon."
Lawson fears popular concerns about global warming will create a constituency for carbon tariffs or other protectionist measures.
Fundamental to his view that the costs of trying to limit climate change will greatly exceed the costs of climate change itself is scepticism about the orthodox view of the science, as expressed by the United Nations Intergovernmental Panel on Climate Change.
He was a prominent member of the House of Lords select committee which held an inquiry and issued a report two years ago which was scathing about the IPCC's processes and conclusions.
"It is claimed the science is settled. It isn't. But even if it were that would not be the end of the matter," he said.
"We don't know how much carbon dioxide will warm the planet or how much economic damage warming will do. So we have no idea what the benefits of decarbonising [the global economy] will be." Man's greatest quality is adaptability, he believes.
"In Finland the average temperature is 5 degrees; in Singapore it is 20. Both are successful economies. If people can successfully cope with that [range] it is not apparent why we can't cope with 3 degrees of warming," he said.
"Global warming, it is generally agreed, produces benefits - if it happens and we will have to see if it happens - as well as disadvantages."
Adaptation means you can pocket those benefits. And it avoids the need for a global agreement, something whose prospects of success Lawson regards as extremely remote, given the chasm between what the United States on the one hand and India and China on the other would regard as equitable sharing of the burden.
"Countries will do their own thing and poor ones which can't adapt will be helped by the richer ones."
The costs of doing so would be small compared with the costs of trying to avert global warming, he argues.
Carbon emissions from vehicles, for example, have continued to climb despite steep rises in the the price of petrol over the past few years.
And the costs of technologies like carbon capture and storage - if they can be made to work - would at least double the price of electricity in countries dependent on fossil fuels.
Lawson dismisses as alarmist claims that climate change unchecked will create large numbers of climate refugees.
It could be argued that it cannot be wise, faced with the prospect of three billion more mouths to feed before the world's population stabilises, to run risks with such fundamental things as how much rain falls where and how fast it evaporates when it does, But Lawson says water scarcity is already a huge problem, and one that can be helped with technological solutions like irrigation and desalination.
Advocates of action on climate change point to the long lags in the physical systems involved, like how long on average a carbon dioxide molecule emitted today will remain in the atmosphere doing whatever it does, and how long it takes the oceans to heat up or cool down.
This, it is argued, imparts a huge asymmetry to the risks that policymakers have to weigh.
"I think that that is the only argument that stands up to any kind of examination at all, but even that one is not convincing.
"You have got to monitor the situation, of course. But there is no sign of runaway global warming - or any warming at all, in fact, since 1998," he said.
"How great a sacrifice is it reasonable to ask the present generation to make to benefit future generations who will be substantially better off?"
Lawson cites the IPCC's own estimate that at the top of its range for potential warming this century, four degrees, global gross domestic product by 2100 would be only 5 per cent lower than it would have been with no warming.
"That means that people in rich countries will be 2.6 times better off than they are now instead of 2.7 times. Developing countries will be eight times better off than they are now instead of nine times."
So what would persuade him that he was wrong?
"If it would appear that there is a significant increase in the world's temperature and that it was having some of the adverse consequences that have been predicted by the alarmists."
Nigel Lawson
* Baron Lawson of Blaby, born in 1932.
* Britain's Secretary of State for Energy from 1981 to 1983.
* Chancellor of the Exchequer from June 1983 to October 1989.
* During both roles in Margaret Thatcher's Government, he was a proponent of privatisation and tax reform.
* TV cook Nigella Lawson is one of his six children.
