This costly effort will reduce the rise in temperature up to 2050 by 0.05 degrees centigrade.

Pause for a second to consider the magnitude of these folk's achievement. The Kyoto Protocol, agreed with difficulty last year, commits the world to cutting its carbon dioxide emissions by 5.2 per cent (from 1990 levels) by 2010, then holding it at that level until 2050. Compared with doing nothing this costly effort will have the effect of reducing the rise in temperature up till 2050 by 0.05 degrees centigrade. So say the "lead authors" of the official UN scientific panel on the matter in the journal Nature last week.

They go on to calculate, in what must be among the most misleadingly precise statistics of all time, that this 0.05 degrees will make the difference between 1,053 million additional people suffering water shortage in 2050 and, er, 1,053 million. In other words, the expensive Kyoto negotiation will achieve an unmeasurably small difference to climate change and its impacts.

That suits their purpose nicely, because the point of the Buenos Aires meeting is to lecture us on the need to do still more hair-shirted things such as ruin our hills with wind farms. But the really startling thing about the figures in the Nature article is this: the UN panel, which has been downgrading its estimates of global warming for several years, while upgrading its calls for urgent action, now admits that its computers predict that the globe will warm by just 1.14 degrees from today's temperature by 2050.

It's official! Global warming by man was a minor problem all along!

We have been here before. When the hole in the ozone layer caught the public's attention in 1985, there was an immediate political effect. By 1987 an international treaty, the Montreal Protocol, had been signed banning chlorofluorocarbons, a treaty that was the model for Kyoto. After several further jamborees for civil servants to tighten it up, the Montreal Protocol was proclaimed a success. America's Environmental Protection Agency even put a figure on it: between $7 and $32 trillion saved in treating skin cancer and cataracts, and in mitigating environmental damage over the next century.

* Doomsday deja vu by Ben Lieberman, European Science and Environment Forum, +44 (0)1223 264 643, £5

So, more than 10 years after Montreal, there is still no evidence that anything has been prevented. UVB-related increases in skin cancer, cataracts and environmental damage have never been found. Melanoma is now not even thought to be caused by the UVB that the ozone layer intercepts. The official story about the ozone layer is a string of myths.

Indeed, far from proving that the precautionary principle makes sense, the ozone story proves the opposite. The economic cost of adjusting to a CFC-free world is estimated in the hundreds of billions of dollars. Would you buy a secondhand treaty from these folk?