The world has until 2020 to reverse the trend of rising greenhouse gas emissions to avoid the most dangerous effects of climate change, the world’s top climate scientists warned on Friday.
Achieving this would reduce the world’s annual gross domestic product by 3 per cent in 2030, the UN expert panel concluded. Emissions have been rising for the past 150 years.
Charles Kolstad, professor of environmental economics at the University of California and a lead author of the report, told the FT: “It is costly but affordable. You do not want to throw that kind of money away. But if you want to accomplish the goal, then the cost is acceptable.”
Cutting greenhouse gas emissions to the required level can be achieved with today’s technologies but bringing them into widespread use is likely to require extensive changes in public policy, according to the report published in Bangkok, Thailand, by the Intergovernmental Panel on Climate Change, a group convened by the UN.
The cost of cutting emissions to the required levels would be about $1,500bn a year from 2020, according to estimates made by the FT based on data published by the IPCC. Global GDP is projected to double from $45,000bn last year to about $90,000bn in 2020.
The IPCC also estimates that $20,000bn must be spent by 2030 on the world’s energy infrastructure which, if used in ways that help to reduce emissions, will help defray the costs.
The report said the cost would be equivalent to shaving growth in the world’s GDP by only 0.12 percentage points a year by 2030.
Most of the technology needed to achieve the necessary cut in emissions is already commercially available, including nuclear power, renewable energy generation and measures that promote energy efficiency.
Geoff Levermore of Manchester University, a lead author, said: “The [report] shows there is the technology available, it is affordable, but that improved government policies around the world are now required to help reduce emissions.”
Michael Grubb of Cambridge University, another lead author, warned against underestimating the effort: “This is really urgent because emissions are galloping off in precisely the wrong direction: they are rising rapidly. That is very sobering.”
If emissions were to peak in 2015, which is viewed as unlikely to be achieved, and thereafter fall by about 50-80 per cent over the next several decades, global warming would be limited to about 2° Celsius above pre-industrial levels, the IPCC report found. The world has already warmed by about 0.7°C in the past century. But if emissions continue to grow until 2030, which is widely viewed as more likely, temperatures would probably rise by 3°C above pre-industrial levels.
This corresponds to a level of greenhouse gases in the atmosphere equivalent to about 535 to 590 parts per million of carbon dioxide, according to the report.
Scientists fear that at levels above that, the likelihood of “feedback” effects which amplify temperature rises could result in runaway climate change – a rapid acceleration in temperature and effects such as more violent storms, desertification and a sharp reduction in agricultural productivity.
This is the third and final part of the most authoritative assessment of climate change to date, which has been six years in the making and drawn on the work of more than 2,500 scientists. The two previous parts of the IPCC’s assessment were released earlier this year.
The key findings have been agreed unanimously by more than 100 governments, including those of the US, China, India and the European Union, and will form the basis for international policy.
They will also provide the framework for discussions, set to begin this December in Bali, on a successor to the Kyoto protocol on climate change, the main provisions of which expire in 2012.
Though the picture of climate change painted in the report is bleak, the report showed signs of agreement that the costs of avoiding the worst effects are not as great as had been feared.
Prof Grubb said: “You could not conceive that this report would have been agreed two years ago, when the US was in a completely different position regarding the economics of climate change.”