Former World bank chief economist Nicholas Stern, who authored the 2006 Stern Review on the effects of climate change, has told business and political leaders assembled at the World Economic Forum in Davos, Switzerland that he may have underestimated the worst effects posed by a changing climate.

Stern's report on the Economics of Climate Change was commissioned by the UK government and released in 2006; it has proven hugely influential on a global scale. Stern looked at likely scenarios to result from climate change and suggested that the benefits of acting to mitigate and prepare for its effects far outweigh the costs of inaction.  

Speaking on the final day of the Forum, Stern said he should have been more frank about the threat of climate change when compiling his initial report. In the 2006 review he investigated the potential effects on water resources, food production, health, and the environment, posited that there is a 75 percent chance global temperatures could increase by 2-3 degrees, and concluded that immediate action – including introducing environmental taxes and creating green jobs – must be taken to avoid massive negative impacts on the global economy.  

He also said that a 5-6 degree increase in long-term average temperature is "a real possibility." In Switzerland on Saturday, Stern said more extreme temperature increases are now probable; he suggested the Earth is "on track for something like [a] four" degree rise by the end of the current century.

Stern, now a cross-bench Peer, described efforts to green the economy as "exciting," but called for more decisive action to avoid the worst possible scenario. He called on governments to facilitate a shift towards more environmentally sustainable technologies.

Lord Stern underlined the seriousness of the threat, stating, "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."

He added, "This is potentially so dangerous that we have to act strongly. Do we want to play Russian roulette with two bullets or one?"

Although the UK government made a pledge to become "the greenest… ever" in 2010, there have been serious questions raised over its willingness to pursue policies of road building, potentially expand airport runways and exploit shale gas through 'fracking' over Britain's potential for renewable energies.