Alexandra is a poor suburb of Johannesburg, but it's within sight of the prestigious Sandton Convention Centre, venue for what's being billed as the most important international conference of this century, the World Summit on Sustainable Development, which opens on 26 August.

We see life in Johannesburg through the eyes of Nankie, a DJ on Alex FM, a community radio station. She's excited by the prospect of delegations from around the world flying in to her home town to debate the world's environmental problems and new ways to create a better, fairer global society. But Nankie and her friends are also hoping the decisions made at the conference will mean change at the grass-roots in Alexandra - and help address the problems of poverty, inequality and lack of basic services that are part of their day-to-day existence.

The kind of poverty the Summit's meant to eradicate is there for all to see in Alex. Ngofy has lived there all his short life: "The environment in Alexandra is a disaster. Even green grass, it's a privilege to live in a house that there's green grass." And Anna Tibaijuka, Executive Director of Habitat, points out that a bad environment can have wider effects: "Definitely, growing up in Johannesburg is not really an easy thing. First of all, you need a lot of family and community support not to get drawn into, for example, anti-social behaviour. So you find the crime rate, for example, in Johannesburg is very high - not because the people of Johannesburg are bad people, but because of this environment in which they are growing up."

The Jo'burg Summit takes place 10 years after the Rio Earth Summit, and a full 30 years after the first international conference convened on the human environment in Stockholm in 1972. But as world leaders prepare for the meeting, just what - this first programme in the new Life series asks - can they really hope to achieve? And why - when governments have failed to deliver on so many of the promises they made at Rio - should the world believe they'll be any more sincere this time?

Certainly, Maurice Strong, who was Secretary-General of the 1992 Rio Earth Summit, is the first to admit that Rio didn't save the world. "But we did provide the basis on which, if governments and others live up to what they agreed to do in Rio, we will be on a pathway to a more sustainable future." But Mostafa Tolba, Executive Director of the UN Environment Programme at the time, is bitter that the promises were never kept. "I was so thrilled with the fact that Maurice Strong managed to get all these people together and they were committing themselves openly in this direction. But it never crossed my mind that this is a show, that we are on Broadway."

UNICEF Executive Director Carol Bellamy says there has been progress in some areas but agrees that too little has been done, especially as the HIV/AIDS pandemic has taken off in the last 10 years - affecting South Africa more than almost any other country. "If you combine poverty, war, HIV/AIDS and a lack of government and private sector leadership, it comes together to say too little has been acomplished."

J K Galbraith, veteran economist and author of The Affluent Society, attributes the failure to follow up Rio to private and public greed. He comes out solidly in favour of more equal national and international society. "I think every civilised country should have a few screams of anguish from the very rich."

This is anathema to the American Right, personified in this programme by Fred Smith, of the Competitive Enterprise Institute. His answer to a sustainable world is "a creative programme of privatisation", because "ownership rights encourage you not only to use wisely today, but to ensure the value of that so you can sell it and utilise that value for the future." He is afraid that NGOs will derail the Summit. "All of the bad ideas in the world today have sorted of melted away in most institutions but they are now totally embodied in the NGO Movement."

But Indian activist Ashok Khosla of the Society for Development Alternatives says that what is needed is "a sense of ownership - that is important for protecting resources" - and this often comes from common property and common ownership, not private ownership.

World Bank President James Wolfensohn is optimistic about improved flows of aid. "Globalisation basically means that we're all living in each other's world. And that being the case, I think there is a much greater readiness today to consider assisting other parts of the world."

So perhaps the Johannesburg Summit will succeed where Rio disappointed, with greater development assistance flows combating poverty.

DJ Nankie sums up what the delegates and the NGOs want out of the Summit. "They want to see people living a better life where they are proud of themselves." And Nankie's friend Phindile says simply: "I think it would help, even if we still had shacks, if we had trees, and a cooling environment for everybody."

Elimination of poverty, in a 'do-able' programme over a set time frame, is what Mostafa Tolba would like to see. J K Galbraith puts it more directly: "There is nothing so important as narrowing the gap between the rich world and the poor, particularly by continued and well considered help to the economic and social development and stability of the poorer countries..." And he bluntly stresses the ethical dimension to the Summit: "There is a moral damage that comes from placing one's personal interest and a country's personal stake ahead of one's sense of humanity for those who are suffering from all of the things that are brought on by poverty."

TRANSCRIPT Read the full transcript of The Road from Rio