Devastated by our hunger to consume and discard

Forty years ago a series of articles appeared in The New Yorker magazine warning the world of an impending ecological disaster. The author, a minor-league scientist called Rachel Carson, published her thesis later that year as a book called Silent Spring. In it she spelled out the dangers posed to the environment of the new generation of agro-chemicals being used to boost food production around the world.

Silent Spring – a reference to the death of songbirds – became an instant classic. It made people aware of the fragility of the natural world to man-made chemicals and it led directly to the creation of the modern environmental movement. The 65,000 delegates to the World Summit on Sustainable Development congregating in Johannesburg this weekend owe much to Carson's pioneering thoughts.

Just 10 years after Silent Spring was published, the first global discussion on the problems facing our natural habitat was held. The 1972 UN Conference on Human Environment in Stockholm led directly to the formation of the UN Environment Programme and the first international declaration to preserve and enhance the natural environment.

The Brundtland commission a decade later formulated a mechanism of how this could be done in its seminal report, Our Common Future. More than a report, this was a manifesto for what humanity needed to do to save the planet. At the heart of this new approach was a concept called "sustainable development" which the report defined as development that "meets the needs of present generations without compromising the ability of future generations to meet their own needs".

Like many of the best sentiments, it is easier said than done. A glimpse at some of the facts is enough to make a pessimist of anyone. In the 400 or so generations that separate the dawn of agriculture, about 10,000 years ago, to the pre-industrial era of the 17th century, the global human population grew from a few million to about 500 million. Since then it has accelerated with alarming speed, reaching 6 billion last year and heading for 9.3 billion by 2050.

Since Carson first wrote so provocatively about the environment, we have lost a fifth of the world's topsoil, a fifth of the best agricultural land and a third of the forests. The "green revolution", which helped to feed the growing population over the same 40-year period with the help of chemical fertilisers and pesticides, is faltering. Global grain production has fallen short of consumption for two consecutive years. The world's surplus is now at its lowest level for two decades, according to Peter Raven, director of the Missouri Botanical Gardens in St Louis.

Meanwhile, some 1.1 billion people – 18 per cent of the world's population – lack access to clean, safe drinking water and more than 2.4 billion others do not have adequate sanitation.

The grinding poverty that so many people are forced to endure is hard to imagine. About 1.2 billion people live on just 65p a day, 850 million are illiterate and 325 million children have never been to school. Some 11 million children under the age of five die each year, many from avoidable illnesses such as diarrhoea caused by tainted water.

In the past decade the world has lost an area of forest the size of Venezuela. More than 11,000 species are listed as threatened with extinction – a fraction of the true number – and more than 800 species are known to have been lost for ever, mostly due to the destruction of their habitats.

To succeed in Johannesburg we must find a way of curbing this almost innate tendency to use, consume and discard whatever there is around us, says Professor Raven.

"We continue to depend on a series of ancient, genetically and socially determined habits and attitudes, many of which seem to have been more suitable for our hunter-gatherer ancestors," he says. "We must adopt new ways of thinking that will serve our descendants well in a world that is crowded beyond imagining, a world in which we shall always be the major ecological force; unless, of course, we destroy ourselves."

Johannesburg is a stab in this new direction. Building on the partial success of the Earth Summit in Rio in 1992, the conference has identified five main areas of concern: water, energy, health, agriculture and biological diversity (Wehab). The assumption is that no one area can be treated in isolation and no single country can act alone.

But unlike Rio, there will be no legally binding treaties. Instead, and to the intense annoyance of environmentalists, it is intended that the meeting will result in "consensus agreements" or more ambitious, but entirely voluntary, "type two" agreements. We can also expect a rather self-congratulatory Johannesburg declaration.

The organisers of the summit hope it will lead to the removal of trade-distorting subsidies and a strengthening of the World Trade Organisation to favour the poorest rather than the richest countries.

And above all, there is the question of what to do about Africa, which seems to have been left behind by the economic development seen elsewhere. In the 1990s China reduced the number of people living in extreme poverty from 360 million to 210 million and in Vietnam it fell by half but in Africa, development efforts have lagged behind just about everywhere else on just about every measure there is.

It is fitting that the summit, therefore, should meet in Africa. But what will it achieve? Andrew Jordan, of the University of East Anglia, says: "Although they do not produce that many hard and fast regulations protecting the environment, 'mega' environmental conferences do promote a long and slow change in attitudes, encouraging governments to adopt statements of principles or 'soft laws' which are then translated into more binding regulations and laws over time."

But time is not a commodity that is in rich supply. When Aldous Huxley first read Silent Spring he remarked that humanity was losing half the subject matter of poetry. And that was 40 years ago.

Summit agenda

Today and tomorrow: Informal discussions

Monday: Opening ceremony. Plenary session:agriculture, health. Side events: democracy debate

Tuesday: Plenary session: finance, technology. Side events: launch of World Development Report

Wednesday: Plenary session: water and sanitation. Side events: debates on children, energy in Africa

Thursday: Plenary session: conclusion. Side events: debates on cleaner fuels and international law

Friday: Plenary session: statements by non-state entities. Side events: HIV and Aids debate

Monday 2 September: Government heads attend; Tony Blair speech

Tuesday 3 September: General debate: "Making it happen"

Wednesday 4 September : General debate. Summit ends

Britain's aims

* The Department for Environment, Food and Rural Affairs (Defra) wants "concerted action rather than new words" to deliver improvements in quality of life for all around the world

* To gain a statement by world leaders demonstrating a commitment to global sustainable development

* A Programme of Implementation setting out the priority actions needed to achieve global sustainable development

* Partnerships involving governments, businesses, NGOs and other stakeholders

* Global action to improve access to clean energy, safe drinking water and adequate sanitation

* Programmes to achieve more sustainable consumption and production

* Global targets on renewable energy, sanitation; loss of natural resources and biodiversity

* Recommitment to honour agreements reached at Monterrey on international aid

* Strong political statement to give momentum to pro-poor trade negotiations