More than 5,000 representatives from 160 countries met in Bonn yesterday for the start of the fifth United Nations Climate Conference, following up the last one in Kyoto, Japan.
The main topic during the 11-day conference, involving at least 100 government ministers, is expected to be the ratification and implementation of the 1997 Kyoto Agreement on the reduction of greenhouse gas production.
Preparations are also on the agenda for the sixth climate conference, scheduled for the end of next year or the start of 2001 in The Hague.
Details of how emissions can be measured and regulated, once the broad principles of the Kyoto Agreement are accepted, will be decided upon only at that stage.
Opening the conference, the German Chancellor, Mr Gerhard Schroder, surprised experts by calling for nations to implement the pact by 2002.
"No other environmental problem poises such a threat to all of humanity," Mr Schroder said. "The Kyoto Protocol must be put into force as soon as possible, by the latest in 2002."
The German Environment Minister, Mr Jurgen Trittin, said the future of the Hague conference depended on substantial steps forward being taken in Bonn.
One sticking point is the US proposal to allow the unlimited purchase of pollution "credits" from other nations, whereas the EU seeks a limit on such credits.
The credits would allow heavily polluting nations such as the US to buy flexibility in reaching their emissions targets from those that fulfil their targets - such as Russia, which won a high limit in earlier talks.
Until now, no large industrialised nation has ratified the agreement, despite the urging of environmental groups such as Greenpeace. In a written introduction to the conference, the UN Secretary General, Mr Kofi Annan, appealed to the industrialised nations to honour the Kyoto Agreement.