George W Bush has said the US was committed to reducing global warming but disappointed many by refusing to drop his opposition to mandatory limits on carbon output.

In a major speech in Washington Mr Bush told representatives of the world's 16 most polluting countries, which account for 80 per cent of harmful emissions, that each nation should design its own strategy, reflecting each country's "different energy resources, stages of development and economic needs".

The US has been fearful that pollution controls would bring heavy job losses. He said improving the environment must not undermine economic growth, and stressed that the two were not mutually exclusive.

"Last year America grew our economy while also reducing greenhouse gases," he said. Mr Bush proposed an international summit next year to set a measurable way of cutting greenhouse gases and proposed a new global fund that would help developing countries pay for clean-energy projects. He also endorsed the UN as the final arena for tackling global warming but implied that America should take the lead in forming a consensus.

The UN has a major climate meeting scheduled for December in Bali and devoted a day to the subject at a meeting with 80 heads of state at its New York headquarters earlier this week. Although delegates were pleased with Mr Bush's conviction, he remains the only major power that opposes mandatory controls.

John Ashton, Britain's climate change envoy, said Mr Bush remained "isolated" on international climate discussions. "I think that the argument that we can do this through voluntary approaches is now pretty much discredited internationally," Mr Ashton said.

"I don't think anything has changed fundamentally as a result of the events in Washington here over the last couple of days," he added.


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