For a planet in peril, the future must start in Johannesburg

As the Earth Summit opens in Johannesburg today, too much fashionable opinion in the rich world has already decided that it is a waste of time and money. Simply because 60,000 people are attending, the argument seems to run, and simply because no binding treaty will emerge from the deliberations, it is all pointless.

This easy consensus, promoted by cynics of both left and right, should be resisted. Of course the summit is a giant talking shop. Of course rich and poor nations are deeply divided over its vast agenda of good intentions. Of course the global environment has continued to be degraded since the last Earth Summit in 1992. Of course Jonathon Porritt, the British Government's own adviser, is right to use this moment to point up the hypocrisies of Tony Blair's environmental record.

But this gathering of 160 governments, thousands of journalists and thousands more pressure groups and lobbyists is far from pointless. In the absence of a world government capable of decreeing and enforcing, like the Chinese regime, a one-child policy across the globe, today's summit is the only way the people of the world can make progress towards a sustainable way of life.

That progress has been painfully slow over the past 10 years. Since world leaders paid lip service to the ideal of "sustainable development" – then a novel concept – in Rio de Janeiro in 1992, the world's population has increased by one seventh to 6.25 billion. Carbon dioxide emissions, which were the main practical focus of the Rio summit, have increased by one tenth, when the intention, formalised in the Kyoto treaty, was to stabilise them by setting cuts in emissions from rich countries against the expected increases from poor ones.

Yet Rio was not a waste of time. It also produced a valuable treaty to protect biodiversity. Above all, it drew the attention of world leaders and their peoples to long-term problems. It helped change attitudes around the globe, not least by committing all the world's countries to the concept of sustainable development. Even George Bush Snr, whose hostile reception at Rio in the run-up to defeat in the American election so upset him that his son will not come to Johannesburg, paid lip service to that ideal.

So far, the American understanding of the concept is rather different from that of the European green movement – on the pragmatic wing of which The Independent places itself. George Bush Jnr's repudiation of Kyoto was a terrible betrayal of the rights of future generations to inherit the planet in better condition than this generation found it.

But simply signing up to the concept of sustainable development matters. Since 1992, attitudes have changed. The green movement has matured, and there is wider acceptance of the fact that there is no inherent conflict between development and the environment – on the contrary, there is much better understanding that technological progress is essential to achieving sustainability. There is no future in trying to go back to a mythological, pre-capitalist, simple life. That does not mean, of course, that big companies and their lobbyists are always forces for good. Mr Porritt, the great guru of green realism, is right to criticise Mr Blair for his naïve adulation of big business, but he is wrong if he encourages a mindless opposition to "globalisation" and multinational companies.

The older, wiser environmental movement understands too that the planet cannot be saved by a voluntary change of lifestyle on the part of individuals, but only through collective action – changing laws and economic rules to change people's perception of their short-term self-interest.

Once, it was fashionable, especially on the left, to say that the problem was not one of population growth but of the unequal distribution of resources. It is no longer possible to deny that the sheer weight of human numbers is the main threat to sustainability. But inequality remains at the heart of the issue because the most effective forms of contraception are education, especially of girls, and higher living standards. At Johannesburg, countries are likely to inch closer to a new settlement between the world's rich and poor, not based on charitable "aid" but on support for sustainable development – that is, economic growth that stabilises population, uses energy efficiently and preserves rainforests and other habitats that are valuable to the whole world.

Rio helped to mobilise the battalions of ideas that are a condition of the kind of global political revolution needed to save the planet. Johannesburg will help to advance that revolution – not least because of the huge attention lavished on it by Western media.

The slowest ship in the world's convoy of environmental awareness is American public opinion. The bloated, resource-hungry American voter is the greatest obstacle to global sustainability. It is the US that blocks Kyoto, which will not even consider taxing international aviation fuel, which refuses to pick up the tab for preserving habitats outside its borders. But attitudes are changing there too. Even in America, to deny the science of global warming has become eccentric. And we should remember that Al Gore, a remarkably green politician by US standards, won more votes than Mr Bush two years ago.

What is more, if there is one foreign politician who has any purchase on the American electorate it is Mr Blair. We should be pleased that he will be in Johannesburg, and that his Government thinks it important enough to send 70 people there. Paradoxically, we should also recognise it may be beneficial that Mr Bush is not there. If he were to attend, he would be the focus of a festival of anti-Americanism, which might be satisfying for all kinds of reasons but which would ultimately be counter-productive in the all-important business of persuading American opinion.

Given that the main value of this summit is as a platform for grand symbolic gestures, it should not be wasted on negative insults aimed at George Bush, big business or Robert Mugabe. The more leaders can use it as an opportunity to persuade their peoples of the urgency of the need for common action to preserve the ecosystem on which human life ultimately depends, the better.