A radical shift from fossil fuels to low-carbon energy would slow world economic growth by only a tiny fraction every year, a new draft U.N. report on tackling global warming said on Friday.
Many governments had complained that an earlier draft was not clear in its estimate of the costs of low-carbon energy, which include solar or wind, nuclear and fossil fuels whose greenhouse gas emissions are captured and buried underground.
The new draft, which is being edited by government officials and scientists in Berlin before publication on Sunday, indicates that world economic losses would be small compared to projected costs of heatwaves, floods, storms and rising sea levels.
The study by the Intergovernmental Panel on Climate Change (IPCC) is a main guide for governments working on a U.N. pact due to be agreed in Paris at the end of 2015 to slow global warming, which the IPCC says is extremely likely to be man-made.
The new text, obtained by Reuters, says that tough action to cut rising greenhouse gas emissions would slow rising world consumption of goods and services by 0.06 percentage point per year in this century, in a range of 0.04 to 0.14.
Economists say the changes in consumption measured by the IPCC are almost identical to changes in the more common yardstick of gross domestic product (GDP). Consumption excludes investments included in GDP.
The earlier draft said consumption losses could be up to 12 percent by 2100 but omitted to clarify that the number is the cumulative result of a small brake every year over a century, rather than a hint of economic slump in 2100.
The new draft also adds context that losses are tiny compared to soaring wealth - consumption is set to rise by anywhere from 300 to 900 percent this century, it says.
Several nations said the losses of 12 percent by 2100 cited in the earlier draft sounded alarming and wanted further clarification.
Britain had said the number "could easily be taken out of context by those opposed to climate action", referring to those who are not convinced that climate change is a man-made problem requiring an urgent fix.
The IPCC draft says trillion-dollar shifts in investments are needed to make low-carbon energies the dominant source of energy by 2050, up from 17 percent now, in a shift from conventional fossil fuels.
The WWF conservation group set up a mock casino outside the Berlin hotel where the IPCC is meeting, urging governments to stop subsidizing fossil fuels and to shift to renewables.
"We can't continue to gamble with the future of the world we depend on," Stefan Singer of the WWF said.
Environmental group Greenpeace said China's rush to develop dirty coal seemed to be coming to an end in a shift that would avert annual greenhouse gas emissions equivalent to those of Australia and Poland combined by 2020.
"Over half of world carbon dioxide emission growth in the past decade has been from China's coal," said Li Shuo of Greenpeace. "China's concern about air pollution may have broken that trend."
Greenpeace projected that curbs adopted by 12 provinces would reduce coal burn by about 350 million tonnes by 2017 and 655 million tonnes by 2020, below projected levels.
The IPCC draft does not attempt a formal cost-benefit analysis of action to keep temperatures to any given level.
(Reporting by Alister Doyle; Editing by Sonya Hepinstall)