Stern's report was attacked for being alarmist when it came out in 2006. But now he is going for a new global environment deal in Copenhagen next year. What are its chances?

The Stern review on the economics of climate change irrevocably altered the climate debate when it came out in October 2006. For the first time, environmentalists who had shouted loudly about the dangers of climate change were joined by an apparently hard-headed economist, commissioned by a government and with a team of 15 economic analysts and modellers at his command.

Nicholas Stern, a former World Bank chief economist, was working at the treasury when he was asked to look at the economics of climate change. The conclusion of his 700-page report--that the world must act quickly or face devastating consequences--was not new, but the language it used was.

Stern has moved on since his review. He became Lord Stern of Brentford last year. No longer in government, he is a professor at the LSE and recently became chairman of the new Grantham Research Institute on Climate Change and the Environment, a result of a grant from philanthropist Jeremy Grantham, the biggest the LSE has ever received.

The climate change world has moved on too. Discussions at Bali in December 2007 produced a consensus to try for a major agreement at a summit in Copenhagen in December 2009. By then, a new US president will have been in office for less than a year. The clock is ticking, but Stern believes a deal is possible. For the last couple of months he has been talking to the Danish, Indian and Australian prime ministers, as well as serving on committees around Europe and advising the British government. He is going out to the Democratic convention in Denver in August, and expects to testify before the US congress for the second time. He recently published "Key Elements of a Global Deal on Climate Change," perhaps the first paper to try to map out the overall structure of a possible world deal.