By Catherine Brahic Climate scientists, economists and policy researchers are all in agreement: limiting long-term global warming is achievable at a “negligible” cost. Now, the responsibility for action lies in the hands of politicians, they say. The cost estimates for stabilising greenhouse gases in the atmosphere were released on Friday in the latest chapter of the 2007 Intergovernmental Panel on Climate Change report: it will cost between 0.2% and 3.0% of global GDP by 2030 (see Price placed on limiting global warming). “Is capping greenhouse gas concentrations achievable? Absolutely yes,” says Saleem Huq, director of the climate change programme at the UK-based International Institute for Environment and Development. “But there are two aspects to ‘achievable’ – the technological and the political. The political is a tougher question.” The immediate political reaction to the new IPCC report is not encouraging for those seeking rapid and substantial actionreductions in emissions. The US, which is the world’s biggest emitter of greenhouse gases and the world’s largest economy, expressed concern. James Connaughton, chairman of the White House Council on Environmental Quality, said the 3.0% reduction in GDP would result in a global recession: “No world leader will pursue a strategy that would lead to economic recession. Our goal is reducing emissions and growing the economy.” The IPCC cost estimates can be put in perspective by comparing them with what the average voter would have to contribute, says Ralf Martin of the London School of Economics, UK. In 2005, UK households had an average weekly income of £350 ($700). Reducing that by 0.2% to achieve the smallest greenhouse gas reduction considered by the IPCC would cost each household £36 ($72) a year. At 3% per year, achieving the greatest reduction considered would cost £546 ($1092). “The cheaper scenario would mean going out to dinner one time less a year, whereas the higher figure gets into the range of having or not having a car,” says Martin. “The higher figure might be a hard sell. However, I would suggest that whether either figure is acceptable depends largely on how it will be sold to voters.” Benito Müller, a climate policy researcher at Oxford University in the UK agrees: “All these things are open to spin. If you put it in so many trillions, everyone gets frightened. But once you put the numbers into perspective they must become politically acceptable. If not, we are being totally irrational.” Müller says the key figure is not the “net GDP cost”, but the extent to which capping greenhouse gas emissions will slow global economic growth. The IPCC says GDP growth will slow by up to 0.12% a year by 2030 if greenhouse gases are stabilised. “That’s negligible,” he says. “We won’t notice it,” says Simon Retallack, head of the climate change department at the Institute for Public Policy Research, a UK-based think tank. He compares the IPCC conclusions with those of the Stern Report, which predicted that inaction could exact a far higher price. “The key issue to bear in mind is that we are talking about an investment rather than mere expenditure,” says Martin. He, too, turns to the Stern Report, which concluded that spending 1% of GDP now to limit climate change will avoid having to spend 5% in the future to tackle its effects. “The question therefore becomes not if we can afford to expend 1% of GDP, but if we can afford to miss out on an investment opportunity leading to a return of more than 400%. Imagine having a savings account with these returns.” According to the IPCC, stabilising greenhouse gases in the atmosphere at 550 parts per million will slow GDP growth by less than 0.1% and could eventually stabilise global temperatures at 2°C above pre-industrial temperatures. In April, the IPCC released a report describing the impacts of such a temperature rise (see Key report to say global warming already happening). A 2°C rise would still mean less food productivity in the tropics, more storms and floods world-wide, losing 30% of the species that are currently at risk of extinction, and widespread coral bleaching. But the effects get much worse with even higher temperatures. At 4.5°C, temperatures will affect food productivity worldwide, health services will begin to be burdened by greater illness, and millions living on coastlines risk being flooded every year. “At what level are we going to stop accepting the damage?” asks Huq. “We have already accepted a certain level. Some species will disappear, some people will lose their lives and livelihoods. The level we now set as a target for capping greenhouse-gas concentrations will decide how much more we lose.” “Aiming to stabilise emissions at 550 ppm is worth doing,” says Myles Allen, of Oxford University in the UK. Allen is a computer modeller and thinks that starting to reduce emissions is the only way to find out how the climate will respond to these reductions, and therefore the only way of confirming what needs to be done to stabilise greenhouse gases. “We are learning by doing, and the main benefit of the IPCC agreement is that we have agreed that it is technically feasible to start doing something now,” he concludes. Climate Change – Want to know more about global warming – the science, impacts and political debate?