THERE will be a lot of hot air produced by the Johannesburg Earth Summit. It will cost a hideous amount of money: £35 million. But it is important that it happens.

In the last ten years, the world's population has increased by 12.5 per cent. There are now 6.25 billion humans tramping the planet. It may sound simplistic, but if every one of those 6.25 billion people starting using supermarket bags at the rate the British do, the entire planet will soon be awash with tatty pieces of disposed plastic bearing the names of big stores.

Unless we try to put our house in order, we cannot expect the poorer nations to do what we say. They'll just do what we do.

Which is why America's attitude of turning its back on the Kyoto pollution agreements was so disappointing. The targets may have been over-optimistic, but at least America was seen to be trying to cut back on its emissions. Why should the poorer countries, who aspire after our Western lifestyles, bother to cut their emissions if a nation as great as America can't even try?

And so carbon dioxide emissions have risen by ten per cent in the last decade. Most people, even in America, now accept that global warming is having a negative effect on our weather patterns, but without targets, how else are we going to try to reduce our emissions?

Yet America, like Europe, has so much to offer the poorer countries. Our new technology is creating cleaner engines and factories which gives us far better lifestyles, free of smog and pea-soupers, than our ancestors enjoyed 50 or 100 years ago. So why aren't we helping the Third World by-pass the pollution age and join us in the cleaner air?

The summit could also make a valid point about democracy. It is the best way to sustainable development. Dictator Robert Mugabe has managed to plunge about six million of his people into poverty in the last two years. The current floods in China may well be exacerbated by corrupt unelected officials pocketing money that was meant to improve defences.

Finally, the summit should be about sharing information. In Ireland, a 10p tax on each supermarket bag has caused a 90 per cent reduction in the number of bags used, down from 100 million a month to seven million.

But here in Britain, only one in 200 supermarket bags is recycled. And we wonder why they litter our streets and verges and clog our landfill sites.

If all we get from the summit is a similar tax and a cleaner local environment, the hot air will not have been for nothing.