cross bench peer and author of the government-commissioned review on climate change that became the reference work for politicians and green campaigners, says he underestimated the risks
, and should have been more "blunt" about the threat
posed to the economy by rising temperatures.
"Looking back, I underestimated the risks. The planet and the atmosphere seem to be absorbing less carbon than we expected, and emissions are rising pretty strongly
. Some of the effects are coming through more quickly than we thought then."
The Stern review, published in 2006, pointed to a 75% chance that global temperatures would rise by between two and three degrees above the long-term average; he now believes we are "on track for something like four degrees ".
He said some countries, including China, had now started to grasp the seriousness of the risks, but governments should now act forcefully to shift their economies
towards less energy-intensive, more environmentally sustainable technologies.
"This is potentially so dangerous that we have to act strongly. Do we want to play Russian roulette with two bullets or one?
Stern said he backed the UK's Climate Change Act
, which commits the government to ambitious carbon reduction targets. But he called for increased investment in greening the economy, saying: "It's a very exciting growth story."
Jim Yong Kim, the new president of the World Bank
, also gives a grave warning about the risk of conflicts over natural resources.
"There will be water and food fights everywhere," Kim said as he pledged to make tackling climate change a priority of his five-year term.
"We have to find climate-friendly ways of encouraging economic growth. The good news is we know they exist".