According to a draft United Nations report, designed to influence efforts to draft a global-warming treaty, the cost of holding rising temperatures to safe levels may reach four per cent of economic output by 2030.
Most scenarios that meet the two-degree Celsius cap on global warming endorsed by world leaders require a 40 per cent to 70 per cent reduction in heat-trapping gases by 2050 from 2010 levels.
Bloomberg newsagency reports the world would need to triple the share of renewable energy, nuclear power and carbon-capture and storage to meet that goal.
“This report shows that two degrees is still technically possible and ought to remain the primary policy target” for climate negotiations that intend to produce a global agreement in 2015, said Bob Ward, policy director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics.
A spokesman for the panel declined to comment on the document.
Bloomberg reports the research is important because it’s intended to influence the direction of UN negotiations involving more than 190 countries on how to combat global warming.
The discussions have been beset by wrangles between developing and industrialized nations over who should bear the cost of tackling climate change.
Countries are trying to divide up by 2015 the burden of emissions limits needed to stave off the worst effects of climate change, including rising sea levels and more frequent droughts.
“Without explicit efforts to reduce greenhouse gas emissions, the fundamental drivers of emissions growth are expected to persist,” according to the study by the UN’s Intergovernmental Panel on Climate Change (IPCC).
Delaying action to curtail greenhouse gases through 2030 would reduce options to stabilize the gases, require much more rapid scale-up of low-carbon technologies and rely more on techniques that take carbon dioxide out of the atmosphere, such as combining burning biomass with carbon capture and storage, the researchers wrote.
The findings are the third installment of three reports summarizing the IPCC’s work.
A final document synthesising the three is scheduled for completion in October.
That document said that a temperature increase of 2.5 degrees Celsius since industrialisation may lead to losses of as much as two per cent of global economic output.
At the same time, it warned “aggregate impacts hide large differences between and within countries.”
“Beyond two degrees you risk potentially catastrophic impacts such as a destabilization of the polar land-based ice sheets that would have very severe economic consequences which are not present in the economic models,” Mr Ward at LSE said.
‘‘You could tell the story of World War II just through GDP, but it wouldn’t tell you about the millions of people who died,’’ he said.
‘‘The losses of livelihoods a result of climate change impacts are not captured by the GDP story.’’
Small island states have argued that even an increase of two degrees may threaten the existence of some of their countries because of the encroachment of rising seas on land and water reservoirs.