According to a Tuesday disclosure by Ottmar Edenhofer, co-chair of the UN panel of climate scientists, to Reuters, the UN working group will consider the costs of "second best" ways of combating global warming, amid uncertainty hovering over the signing up of all countries for the action led by the UN.

The UN's December-last-year summit at Copenhagen worked out only a non-binding agreement among nearly 120 nations - of a possible total of 194 - aimed at restricting global warming to below 2 degrees Celsius (3.6F) above pre-industrial times.

Noting that the last UN report in 2007 presumed the participation of all countries in the action against global warming and the availability of new technologies to curb greenhouse gases, Edenhofer said that the next reports in 2013-14 by the Intergovernmental Panel on Climate Change (IPCC) will now include other options as well.

Saying that the IPCC is facing calls for a revamp of its management and better fact-checking after the erroneous 2007 assessment, Edenhofer told Reuters: "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."

Furthermore, adding that the 2007 report did not expect the current extent of technological progress for some sources of renewable energy, Edenhofer said that the new report will also look at the likely side-effects of fighting global warming.