* U.N. widens climate cost studies if not all take part
* "More realistic" than 2007 report-Edenhofer
Alister Doyle, Reuters AlertNet 31 Aug 10;
OSLO, Aug 31 (Reuters) - The U.N. panel of climate scientists will look at the costs of "second best" ways of fighting global warming amid doubts that all countries will sign up to U.N.-led action, a leading expert said on Tuesday.
Ottmar Edenhofer, co-chair of the U.N. working group looking at the economics of global warming, said the last U.N. report in 2007 had assumed that all countries would take part and that new technologies for curbing greenhouse gases would be available.
The next reports in 2013-14 by the Intergovernmental Panel on Climate Change (IPCC), which is facing calls for an overhaul of its management and better fact-checking after errors in the 2007 assessment, will include other options.
"We intend to carry out 'second best' scenarios, where we assume we have a fragmented climate regime, where we have limited availability of technologies, to describe a much more realistic policy space," Edenhofer told Reuters by telephone.
The U.N.'s Copenhagen summit in December 2009 agreed only a non-binding deal among about 120 nations -- of a possible total of 194 -- aimed at limiting global warming to below 2 degrees Celsius (3.6F) above pre-industrial times.
The United States, the number two greenhouse gas emitter after China, has not followed other industrialised nations in setting a cap on its greenhouse gas emissions despite pleas by President Barack Obama.
Edenhofer, who is also chief economist at the Potsdam Institute for Climate Impact Research in Germany, declined to estimate the likely costs of such "second best" scenarios.
SLOW GDP
The 2007 report said a strong fight against global warming would slow world gross domestic product (GDP) by less than 0.12 percent a year, curbing world GDP by a total of less than 3 percent in 2030.
Most of the costs are billions of dollars to shift from fossil fuels to clean energies such as wind or solar power. In some renewable energies, Edenhofer said there had been more technological progress than expected in the 2007 report.
He also said that new report would look at possible side-effects of combating global warming. Even harmless-sounding strategies, such as planting trees that soak up greenhouse gases, might have side-effects by displacing cropland.
"This is not a risk-less operation...The use of biomass (plants) would probably have severe impacts on food production, on food security, which is a very crucial issue here," he said.
An independent review group urged reforms to the IPCC on Monday after mistakes in the 2007 report such as exaggerating the thaw of the Himalayas.
Edenhofer said he welcomed the proposed reforms by the InterAcademy Council. The review urged the IPCC to ensure that a full range of "thoughtful scientific views" were heard.
(Editing by Peter Graff)
