A similar problem looms for the August 26-September 4 Earth Summit in Johannesburg, where the buzzword of sustainable development will be on the lips of up to 50,000 participants.

With rare exceptions, everyone will agree that sustainable development is a Good Thing. After all, everyone wants prosperity and no one wants it to damage the environment.

But try taking the debate a little further, and things start to get messy.

For one thing, the sacred concept is open to myriad interpretations.

And transforming it into something meaningful is -- like sausage-making -- very often an art of adding colouring, flavouring and a big dollop of indigestible matter.

"Sustainable development can mean a whole range of things to different people," says Paul Horsman, an energy specialist with Greenpeace.

The term of sustainable development first saw daylight in 1980 when it was coined by a private research organisation, the World Conservation Union (IUCN).

It was expounded in a report in 1987 set down for the UN by the Brundtland Commission Development, named after the former Norwegian prime minister, Gro Harlem Brundtland, and then enshrined in 1992 at the first Earth Summit, held in Rio 10 years ago.

The definition: "Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs."

Underpinning it is the idea of preserving environmental assets and regenerating natural resources and balancing this with the need for prosperity and growth in the Third World and and support for vulnerable groups and poor countries.

However, "it is not a scientific concept, and there are many ways of interpreting it," says Michel Colombier, who works at a new French research thinktank, the Institute for Sustainable Development and International Relations.

Outside the debating arena, sustainable development plays a continuous dilemma in our everyday lives.

Yes, we all say we want clean air -- but then, we may also need a car to earn our living, and to use it is to bequeath to future generations our carbon pollution, the force behind global warming.

Among a small minority of ultra-greenies, growth of any kind is unsustainable.

But, says Martin Rocholl, director of Friends of the Earth Europe, the vast majority of environmentally-conscious people do not agree with that at all, and simply want better and fairer use of resources.

"For me, sustainability means two things. First we've got to live within the framework that the planet gives us, and that means producing only so much pollution that the planet can take and only take the resources that the planet can offer.

"The second is the equity principle. Every human being has the right to use these resources in the same amount."

The corporate world, too, has its ultras. Radical conservatives consider sustainable development to be vacuous and a costly brake on growth.

But, again, that is not the overall picture.

WWF's Jennifer Morgan says it is true that many corporations use sustainable development as a pretext "to greenwash their activities" -- to unveil projects that have negligible environmental value but help to promote a green image.

So far, few companies have really signed up to sustainable development that can be scientifically measured, she says.

On the other hand, the fact that sustainable development has entered corporate thinking, even in a truncated form, is a plus. Many companies make environmental impact reports and consult with local stakeholders before making an investment decision, says Morgan.

Even amongst laissez-faire business thinkers, the ideology is becoming tinged with green.

Ecologists have been saying for years that the true environmental cost of a resource should be reflected in a product's retail price.

The idea is now cautiously starting to appeal to some free marketeers, partly because pricing pressure is a highly effective way of attacking environmental abuse.

SPACE.WIRE