The journey to Johannesburg

BBC News Interactive looks at the efforts to steer the world on to a sustainable path.

World leaders deliver short speeches on a series of subjects at the summit. South African President Thabo Mbeki urges them to take firm action on poverty and the environment. UK Prime Minister Tony Blair delivers a veiled rebuke to America as he says eveyone must face up to climate change.

Former President of South Africa, Nelson Mandela, says giving people clean water should be high on the list of the world's priorities. At the opening of the WaterDome exhibition at the summit, he tells delegates, "In impoverishment it is the absence of clean water that strikes me most strongly."

Observers at the summit say agreement on agriculture will prove difficult, as developing countries say that both the Europeans and Americans are not prepared to discuss reform of the world trade system and the reduction of subsidies to agriculture.

In his opening address to delegates at the summit, South Africa's President Thabo Mbeki calls for an end to the world order of "survival of the fittest". Delegates from over 170 countries face the challenge of reducing the number of people in poverty while protecting the world's environment.

Kyoto in Japan hosts a marathon session of talks on tackling climate change. Exhausted delegates finally reach a decision to reduce global greenhouse gas emissions by 5%. Environmentalists say concessions offered to polluting nations will do little to stop global warming.

The 'Rio+5' summit in New York assesses progress made since the 1992 Earth Summit. European countries criticise America's failure to set targets to reduce carbon dixoide emissions. Environmentalists say the US is being squeezed by sceptical industry lobby groups.

The world's attention focuses on Brazil's capital for 14 days as world leaders gather to address growing environmental concerns. Despite commitments to tackle deforestation, global warming and the launch of the 'Agenda 21' action plan, critics say the summit fails to deliver.

A report by a UN commission, led by the Norwegian Prime Minister Gro Harlem Bruntland, alerts the world to the need of ensuring economic development does not deplete natural resources or harm the environment. The Brundtland Report offers a framework for moving towards a sustainable world.

The first time world leaders gather to discuss growing concerns of evironmental damage is at the UN's summit on the human environment in Stockholm. Pollution and overpopulation top the list of concerns. Speaking ahead of the summit, its co-ordinator, Dr Maurice Strong, offers an ominous warning: "Doomsday is a possibility".