More than 70 presidents and prime ministers have pledged to attend a follow-up event in New York, Earth Summit plus Five, later this month.
But it looks like being as empty an event as the 1992 meeting in Brazil - another long text to be negotiated which no one reads and is soon forgotten, stirring speeches, empty agreements. For the record, the UN Conference on Environment and Development (its official name) is largely one of failure.
The developed countries, with the exception of the United States, pledged to strive to increase their aid to the Third World; it has fallen sharply since. They said that by 2000 they would stabilise their rising emissions of climate-changing greenhouse gases; it now looks certain that the great majority will fail to keep that commitment, with Britain and Germany the two major exceptions.
For at least a quarter of a century, it has been convincingly argued that humanity is on a road to disaster because it is failing to take a long-term view of its crucial relations with nature and natural resources.
It is not the end of the world which is looming, but a series of interconnected crises - climate change, lack of fresh water and fertile soil, collapsing fish stocks - in the first few decades of the next century. Unless action is taken now, the costs of adapting to this degraded world will be colossal, and the toll will be measured in ill health, early deaths and insecurity as well as in money. The harm mounts as each year of inaction passes.
Since 1992 there has been strong economic growth globally, partly from huge increases in international trade and private-sector investment flowing from rich countries to poor. So development is taking place: by and large people around the planet are living longer, enjoying better health, seeing living standards rise. And while much of that prosperity does more environmental damage, it also provides societies with the resources to tackle the problems - if they chose to.
But the gap between rich and poor is widening, within countries and between them. The planet could do with a real Earth Summit, when world leaders really do make history and change course towards sustainability. But at the moment, New York seems more likely to consist of mere words and a group photograph.
Troubled planet, page 6
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