IN JUNE 1972, I was in Stockholm, at the UN Conference on the Human Environment. In June 1992, I was in Rio de Janeiro for the UN Conference on Environment and Development. What was the difference? Rio was bigger.

In Stockholm, every meeting was within ten minutes' walking distance. Except, that is, for Hog Farm, an eco-hippy commune on a disused airfield, which one visited by taking a free 20-minute ride on a black bus -- fuelled, so they said, by chicken shit.

Rio is a bigger city than Stockholm so, of course, it had a bigger conference. The UN conference was in what felt like a designer airport terminal, named Riocentro because it is at least 20 miles from the centre of the city. One got there in an hour and a half if one was lucky, in air-conditioned buses fuelled, so they said, by alcohol made from sugarcane.

Because Brazil is bigger than Sweden, Rio had far more soldiers: one every 30 yards between the centre of Rio and Riocentro. Plus tanks, helicopters, and "secret" police with identical sunglasses and leather jackets. Most of the soldiers had two-way radios, and the more important NGO representatives rented portable telephones, so they could Keep in Touch with Their Constituencies.

Rio had far more presidents and prime ministers than Stockholm. One of the few prime ministers in Stockholm was Sweden's Olaf Palme, who had promised the US not to raise the Vietnam War in the conference. He didn't. Instead, he spoke at a mass anti-war rally in the city centre on Sunday morning. The Americans were very cross indeed.

The Americans got very cross in Rio as well, because lots of other governments signed the biodiversity convention, even after President Bush had said it would hurt American industry. (It won't. But in an election year it is important for US presidents not to appear to be pushed around by foreigners.)

Over a hundred heads of government came to Rio, more than have ever been gathered together in one place before. Even the taxi-drivers knew this, as they cursed the traffic jams caused by over a hundred motorcades. Every Rio cab had a poster in its back window, saying "Rio is the capital of the World". For a week or so, I suppose it was.

Rio produced Agenda 21, an impressive wish-list of all the things governments agreed would be a good idea for the 21st century (but not before). More food, less desertification. More free markets, less state control. More homes, less pollution. More rainforests and less poverty.

Agenda 21 didn't include armaments, population, trade, transnational companies and nuclear power because diplomats had agreed in advance that governments were unlikely to agree what to do about them.

The main thing that governments agreed upon was that Agenda 21 was going to be very expensive, and that someone else ought to pay for it. This was mainly discussed in terms of "aid". There was not much talk of social justice, or of the structural injustice of a planet where the poor get poorer and the rich get richer, or of the quaint idea that human rights include the right not to live and die in poverty.

Stockholm had only a few hundred NGOs: Rio had thousands. Many of them were surprised and indignant about all this. If governments can't agree on what should be done, then NGOs must agree instead. So some of the NGOs stayed up nights "negotiating" what they called NGO "treaties". For some the purpose was simply to demonstrate that international agreements are possible, and to produce a text that was more sensible than the non-agreements being argued over by the diplomats in Riocentro. But many among the new class of international NGO bureaucrats take themselves more seriously than this. So they held formal signing ceremonies, pledging their organisations to implement these "treaties".

Undoubtedly, the best aspect of Rio was the strong and visible participation of indigenous peoples, mainly from the Americas, but some from other parts of the world. They underlined the one really new insight of Rio: that human cultural diversity is under even greater threat than our planet's biological diversity, and that cultural diversity and biodiversity are intimately connected. For Native Americans, 1992 is the 500th anniversary of the European "discovery" of their continent: they celebrated by reversing the traditional colonial process and selling beads to the white men.

Rio's NGO Forum was a splendid place for meeting people, and for exchanging ideas and information. From a Norwegian and a Russian NGO, for example, I learned of the environmental horror of the former Soviet nuclear reprocessing plant, where used reactor rods are converted into weapons-grade plutonium, and where today a leaking earth dam threatens to release into the Arctic Ocean (and its rich fisheries) one hundred times more radioactivity than what came out of Chernobyl.

But the NGO Forum was curiously incomplete. It was partly its location, inside 30 hot and humid plastic tents alongside a motorway; it was partly the commercial atmosphere, with hundreds of NGO stalls selling T-shirts and posters; it was partly the need to help finance it by selling day-passes to Rio schoolchildren; it was partly the assumption that simply by getting thousands of NGO people to Rio, and by erecting enough meeting-tents, hot-dog stalls and exhibit booths, something meaningful would emerge by itself.

Stockholm wasn't as big as Rio, but I think it had a soul. I expect Rio's soul was there too, somewhere. Maybe it was arrested by the military police. Or lost in a Copacabana nightclub. Or deported by a benevolent government, as were Rio's street children, a week or two before the conference.

Like the missing street kids, it may turn up again one day.

---Jon Tinker is the president of the Panos Institute of London. He is also a well-known columnist and environmentalist.