Focus on 2050, says new climate change study
Policymakers seeking to cut greenhouse gas emissions must focus on what needs to be achieved by 2050 if we are to keep options viable for all possible climate change scenarios, says new research published in the Proceedings of the National Academy of Sciences (PNAS). The study, carried out by a team of researchers from the International Institute for Applied Systems Analysis (IIASA) in Austria, the Energy Research Centre of the Netherlands and the National Center for Atmospheric Research (NCAR) in the US, is the first of its kind to use a detailed energy system model to analyse the relationship between targets for 2050 and the likelihood of achieving long-term outcomes. 'Setting mid-century targets can help preserve long-term policy options while managing the risks and costs that come with long-term goals,' said Professor Brian O'Neill, a scientist at NCAR and co-lead author of the study. Average global temperatures have increased by 1°C since the Industrial Revolution, mostly driven by greenhouse gas emissions (predominantly carbon dioxide) from human activities such as deforestation and industrialisation. The researchers used a computer simulation technique called an 'integrated assessment model' to play out a series of possible interactions between the energy sector and the climate over the coming years. The team began by using a 'business as usual' scenario that predicted levels of climate change by 2050 if no greenhouse gas reduction legislation is put into place. They then went on to analyse the implications of restricting emissions up to 2050 by using a range of different measures. The team focused on analysing how emission levels in 2050 would affect the feasibility of meeting end-of-century emission reduction deadlines. For example, they looked at what will need to be done if we are to meet the end-of-century target advocated by many governments, of keeping global temperatures to within 2°C of pre-industrial levels. Two 'business as usual' scenarios showed that to be in with a 50% chance of meeting the 2°C target, emissions would need to be reduced by 20% below 2000 levels by 2050. In a second scenario where the demand for more resources such as land, energy and consumer goods grows more rapidly than predicted, the reduction level would have to be 50%. The team acknowledged that such a steep reduction is barely feasible. 'Our simulations show that in some cases, even if we do everything possible to reduce emissions between now and 2050, we'd only have even odds of hitting the 2°C target - and then only if we also did everything possible over the second half of the century too,' explained Dr Keywan Riahi, a scientist at IIASA and a co-author of the study. The team used a number of scenarios for possible energy reductions, such as how quickly the world could switch to low-carbon energy sources like nuclear fission, wind power and biomass. Carbon capture and storage was also considered. Not included in the equation were energy sources that have not been demonstrated as safe or viable such as nuclear fusion and geo-engineering. At the United Nations Climate Change Conference in Copenhagen, Denmark in December, many nations recognised the importance of limiting global warming to 2°C, but an agreement on a 2050 target was not reached. 'Even if you agree on a long-term goal, without limiting emissions sufficiently over the next several decades, you may find you're unable to achieve it. There's a risk that potentially desirable options will no longer be technologically feasible, or will be prohibitively expensive to achieve,' warned Professor O'Neill. 'Our research suggests that, provided we adopt an effective long-term strategy, our emissions can be higher in 2050 than some proposals have advocated while still holding to 2°C in the long run.'
Countries
Austria, Netherlands, United States