Although the agreement isn’t a binding one, environmental analysts said they indicated a shift in opinion among legislators, and could well be a precursor of positive changes to come.

Big names including Richard Branson, German Chancellor Angela Merkel and World Bank President Paul Wolfowitz spoke at the event, which was organised by the environmental group, Global Legislators Organisation for a Balanced Environment (GLOBE).

Among measures discussed in the meeting was a proposal that there should be a maximum acceptable level for carbon dioxide in the atmosphere, with countries and businesses working to cap and trade emissions.

Delegates also agreed that any agreement must also include developing nations, though America needed to act quickly to cut emissions to set an example to the emerging economies of China and India.

The UK contingent was led by Elliot Morley, a British MP and close ally of Tony Blair. Speaking to Radio 4’s Today Programme, Morley said that he was “very happy with this outcome. This is the most detailed statement that has ever come out of a Globe meeting.

It contains a number of broad principles that all the countries here are generally supportive of in terms of the way forward.” He added that the discussions had been “a great step forward in terms of building confidence.”

US Senator Joe Lieberman said he was hopeful that America would soon come round to cutting its emissions. “I want to make a prediction, which is that the Congress of the United States will enact a nationwide law mandating substantial reductions in greenhouse gases before the end of this Congress or early in the next.”