A key element of the international plan to address climate change is in jeopardy after several of the most powerful nations failed to confirm a previous commitment to halve greenhouse gas emissions by 2050.

The Asia-Pacific Economic Co-operation (Apec) forum, which includes the US, China, Japan and Russia, deleted the commitment from the final version of the official communiqué issued after a two-day meeting in Singapore. The commitment had been made by G8 leaders at L’Aquila in Italy in July and the decision to remove it is a retrograde step.

The resolve of world leaders to take firm action on climate change appears to be weakening, with President Obama confirming that there would be no legally binding deal at the UN summit in Copenhagen next month.

Officials at the Apec meeting said the view of Mr Obama, President Hu Jintao of China and other leaders was that Copenhagen was merely a “staging post” towards a global deal on climate change. They said a legally binding deal was very unlikely to be agreed until late next year.

The Apec communiqué talked only vaguely of working “towards an ambitious outcome in Copenhagen”. It failed to mention any targets, including those previously agreed.

A draft version of the Apec communiqué said that “global emissions will need . . . to be reduced to 50 per cent below 1990 levels by 2050”. But the subsequent version was non-committal.

Most climate scientists believe that a 50 per cent reduction in global emissions by 2050 is the minimum needed to have a chance of avoiding catastrophic change. Chinese officials made it clear that they regarded the original draft as controversial. “If we put it in this [final] statement, I think it would disrupt the negotiation process,” Yi Xianliang, a Chinese foreign ministry official, said.

Michael Froman, a senior climate change negotiator for the United States, said: “I don’t think the negotiations have proceeded in such a way that many of the leaders thought it was likely that we were going to achieve a final agreement in Copenhagen.”

Ed Miliband, the UK’s Energy and Climate Change Secretary, tried to talk up the prospects of eventually agreeing a deal. He said: “It’s a bit like when you buy a house. Exchange may happen at Copenhagen and completion some months afterwards. What is most important, as far as I am concerned, is to get a really ambitious set of commitments from all world leaders.” He urged Mr Obama to commit to attending the Copenhagen conference.

Mr Obama has said that he would go to Copenhagen if he was confident that his presence would secure a meaningful agreement.

Joss Garman, Greenpeace climate campaigner, said: “It’s been twelve years since Kyoto and two years since negotiations began on Copenhagen, but now Obama says we need another year of talks about talks. The world can’t afford more prevarication and procrastination.”

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