CLIMATE CHANGE could tilt the world's economy into the worst global recession in recent history, a report will warn next week.

Sir Nicholas Stern, a former chief economist with the World Bank, will warn that governments need to tackle the problem head on by cutting emissions or face economic ruin. The findings, due to be released on Monday, will turn economic argument about global warming on its head by insisting that fighting global warming will save industrial nations money. The United States refused to join the Kyoto protocol, the international agreement on greenhouse gas emissions, because President George Bush said it would harm the economy.

The contents of the Stern review into the economics of climate change — commissioned by the U.K. Treasury — have been kept secret since the nature of the work was revealed to the world's Environment Ministers in Mexico this month. But Sir David King, the British Government's chief scientific adviser, on Wednesday gave The Guardian a preview of its main findings.

Talking at a climate change conference in Birmingham, England, he said: "All of [Stern's] detailed modelling out to the year 2100 is going to indicate first of all that if we don't take global action we are going to see a massive downturn in global economies." He added: "If no action is taken we will be faced with the kind of downturn that has not been seen since the great depression and the two world wars." Sir David called the review "the most detailed economic analysis that I think has yet been conducted."

The review will highlight the threat of sea level rise. Sir David said: "If you look at sea level rises alone and the impact that will have on global economies where cities are becoming inundated by flooding ... this will cause the displacement of ... hundreds of millions of people."

Sir Nicholas will argue that tackling the problem may not prove as economically painful as some experts predict. Investment in low-carbon technologies could stimulate the global economy. Sir David said: "[Stern's] analysis, I think, will also surprise many people in terms of the relatively small cost of action."

The International Energy Agency predicts that $15 trillion of investment in new energy sources will be required over the next 15 years.

"The massive investment programme that's ahead of us is an opportunity for us to move towards a zero carbon energy system. The investment process is going to act quite possibly in the opposite direction to an economic downturn," Sir David said.

He added that achieving global political consensus would be extremely difficult. "In my view this is the biggest challenge our global political system has ever been faced with.We've never been faced with a decision where collective decision making is required by all major countries." The timescale too is unprecedented. "Actions being asked of the political system today are only going to play through into mid-century and beyond. So for the first time we are asking a global political system to make decisions around risks to their populations that are well outside the time period of any election process."

He drew parallels between scientific advice on global warming and advice from seismologists ahead of the December 26, 2004 tsunami. A month before the disaster a delegation visited governments around the Indian Ocean to warn about the extreme danger posed by tectonic activity under the sea. No government chose to act on the advice. "$30 million as the cost to install some kind of early warning system presumably looked like a lot of money." Sir David said such a system could have saved 150,000 lives. —