Co-benefits of post-2012 global GHG-mitigation policies

This report provides an analysis of the impact of global greenhouse gas policies on traditional air pollutants using the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model in the time horizon up to 2050. The integrated assessment framework of GAINS has been linked through an interface to the POLES global energy system model so that different global energy pathways can be implemented and examined. The impact analysis has been carried out based on projections of energy use data provided by the POLES model for two different climate policy scenarios, i.e., for a current policy Baseline scenario without any global greenhouse gas mitigation efforts, and a 2-degree Centigrade climate Mitigation scenario which assumes internationally coordinated action to mitigate climate change. Outcomes of the analysis are reported globally and for key world regions: EU-27, China, India and the US. The assessment takes into account current air pollution control legislation in each country. The results of scenario calculations for SO2, NOx and PM2.5 emissions, air pollution control costs, as well as health and environmental impacts, indicate significant scope for co-benefits made possible through climate policies. Climate mitigation measures appear to be more effective in reducing oxides of sulphur and nitrogen, while emissions of particulate matter are reduced to a smaller extent. Decarbonisation of the global energy system by 2050 results in SO2 and NOx emissions lower by two-thirds than in the world without GHG-abatement efforts. Corresponding reduction in the emissions of PM2.5 is estimated at about 30% relative to the Baseline and is particularly sensitive to the assumptions on projected biomass combustion. Expenditures on air pollution control under the global climate mitigation regime are reduced in 2050 by 250 billion Euros when compared to the Baseline scenario. Under the GAINS cost assumptions the largest potential for cost savings is reported for the transport sector, followed by savings in the power generation sector. Around one third of financial co-benefits estimated world-wide in this study by 2050 are allocated to China, while an annual cost saving of 35 billion Euros is estimated for the EU member countries if the current air pollution legislation and climate policies are adopted in parallel. This study also quantifies health impacts of air pollution in Europe, China and India in terms of loss of life expectancy related to the exposure from anthropogenic emissions of PM2.5, as well as in terms of premature mortality due to ground-level ozone. For example in China, current ambient concentrations of PM2.5 are responsible for 38 months-losses in the average life expectancy. In 2050, the global GHG-mitigating strategies reduce this indicator in China by 16 months. In addition, decrease of ozone concentrations in the three regions as estimated for the climate Mitigation scenario in 2050 might save nearly 80,000 cases of premature death per year. Similarly significant are reductions of impacts on ecosystems due to acidification and eutrophication.