The sheer vitriol is the most striking thing. Reputable scientists who raise questions about climate change, backing their doubts with data, are howled down as heretics. The UN-Stern-Kyoto thesis is considered to be above criticism.

Simply to point out that there are few hard facts to go on, and that we are all necessarily engaging in a degree of guesswork, is to open yourself to the charge of being in the pay of the oil corporations. This allegation, when you think about it, is daft. No one would condemn his grandchildren to extinction simply to suck up to ExxonMobil.

Yet such paranoia is no longer confined to Greenpeace. It can be found, too, in the statements of the Royal Society, and even of government ministers.

It is true that oil companies have funded meteorological studies, some of which have been tendentious. But big business is not the only party with a vested interest. Green pressure groups need to keep the rest of us in a state of panic so that we keep sending them our money.

Government bodies, too, like to maximise the threat in order to get grants (they pulled the same trick with CJD and with avian flu). Governments themselves are attracted to any science that justifies enlarging their powers.

And the UN, which would be charged with administering any international emission reductions programme, has the greatest vested interest of all.

In the circumstances, the best we can do is to look hard-headedly at the evidence.

This is what Christopher Monckton has done in two reports for this newspaper. He does not deny that the world is getting hotter, although the rate of calefaction is far from clear, and Europe was probably warmer 1,000 years ago than today. He accepts, too, that there is a link between global warming and greenhouse gases, though there is no consensus about the precise correlation.

Yet, reading his findings, it is hard not to feel that the Stern report might create a monstrous misallocation of resources. We could give housing and clean water to the entire world, and eliminate all major diseases, for just a fifth of what Stern will cost. We ought, in other words, to be absolutely certain of the gains before we start. As yet, we are not.