Apparently we have been busy global dimming for years. How we did it is by shoving lots of sooty particles up into the atmosphere which makes the clouds more reflective and cools down underneath them. At the same time of course we have been producing C02 which should warm us up, but the warming hasn't been as much as expected, because of the dimming. OK got that. Two competing effects, one partially cancellng the effects of the other. Result of dimming has been 20% less sunlight so presumably we should be 20% hotter by now. Stop dimming and real global warming kicks in - ice caps melting and before that billions of tons of methane hydrate frozen on sea beds bubbles up and severely accelerates greenhouse effect. Getting there we will have floods, storms, crop failure, famine and the full 4 horseman thing.

Apparently (I use the word twice to indicate some degree of scepticism), all was revealed on the three days after 9/11 when all the aeroplanes in the USA were grounded, there were no condensation trails and the temperature range expanded significantly. Thank you Mr Bin Liner. I think on balance he might become a saint amongst the tree hugging fraternity for all the wrong reasons. Perhaps not yet though.

Global dimming makes a lot more sense of global warming, if that isn't a contradiction in terms. If only because as human beings we have been so dim as not to twig what was happening. One wonders exactly why. Surely the global warming brigade have done experiments to work out the quantitative relationship between the % of CO2 and the temperature rise in a given volume of air under a given level of radiation? Perhaps not.

The worrying thing is that if we cut back on global dimming then global warming kicks in, but we can't carry on dimming because that is what is producing warming. The Europeans have cut back on the dimming but the Americans, Indians, Russians and Chinese have not, and even the Europeans are still warming.... so you can guess what the result will be.

Lets get back to those good old nuclear power stations, steam trains, cars that use fuel cells and burn hydrogen asap and may be, if we do it now, and are very, very lucky, spaceship earth will still be habitable at the end of this century.