Some 2,000 delegates from 162 countries and dozens of specialist agencies will gather in Germany for the two-week conference, the first to get into the nuts and bolts of a new global-warming agreement meant to take effect after 2012.

The meeting builds on a landmark accord reached last December on the Indonesian island of Bali which, for the first time, held out the promise that the United States, China and India will join a coordinated effort to control carbon emissions blamed for the unnatural heating of the Earth.

The Bali conference agreed to conclude a new climate-change treaty by December 2009. Another conference four months later in Bangkok adopted a negotiating timetable. In Bonn, "the real work is now only beginning," said Yvo de Boer, the UN's top climate-change official.

Scientists say the world's carbon emissions must peak within the next 10 to 15 years and then fall by half by mid-century to avoid potentially catastrophic changes in weather patterns, a rise in sea levels that would threaten coastal cities and the mass extinction of plants and animals.

The new-climate change pact will follow the first phase of the 1997 Kyoto Protocol, which requires 37 industrialised nations to reduce greenhouse-gas emissions an average of 5 per cent below 1990 levels by 2012.

The United States is the only industrialised nation not to have ratified Kyoto. Negotiators hope Washington's consent to the Bali "action plan" marked the end of its hostility toward working with other countries to contain global warming.

"Their attitude, their activity, has changed very much in the recent year. It's really a big change," said Andrej Kranjc of Slovenia, the head of the European Union delegation.

Still, the US administration of George Bush rejects specific and mandatory targets to reduce emissions over the next dozen years. And countries like India and China question why they should accept limits on their development without commitments from the US – the world's largest per-capita polluter by far. Delegates say such major decisions must wait for the new US administration next January.

"It's unlikely we're going to make lots of progress because we need strong signals from the US, and that's not going happen until the election," said Ian Fry, the delegate from the tiny Pacific nation of Tuvalu.

BACKGROUND

THE Bonn meeting is the second of eight meant to clinch by 2009 a broader and tougher climate treaty to come into force after the first round of the Kyoto Protocol ends in 2012.

Kyoto binds the greenhouse gas emissions of some 37 industrialised countries, but neither of the world's top two emitters – the United States and China – have signed up.

The basic outline of the post-Kyoto agreement should be ready by next summer to prepare for the December conference in Copenhagen, Denmark, where the new pact should be adopted.