Affordable energy supply and reductions in emissions of local air pollution and greenhouse gases are each important aspects of South Africa's goals. Many traditional solutions, however, work in contradiction to one another. This work investigates effects on estimated emissions and costs of mitigation strategies using the Greenhouse Gas and Air Pollution Interaction Synergies (GAINS) model to identify policies that satisfy multiple goals. Eight scenarios that describe air pollution control options and mixes of energy production technologies are implemented in GAINS, which quantifies country-wide air pollution and greenhouse emissions and costs of controls. Emissions and costs trajectories are compared to the business as usual case, which projects CO2 emissions to increase by 60% by 2050 compared to 2015. Results show that replacing all coal generation with renewables reduces CO2 emissions in 2050 by 8% compared to 2015, and that aggressive policy targeting the whole energy sector reduces CO2 emissions in 2050 by 40%. GAINS is used to show co-benefits and tradeoffs of each scenario, such as reductions in emissions control costs that accompany a switch to renewables. The approach provides supporting evidence for policies that exploit co-benefits and avoid contradictions by assessing multiple aspects of the energy sector within the integrated framework provided by the GAINS modeling platform.

Climate change mitigation and air quality management are mostly addressed separately in South African legal acts and policies. This approach is not always coherent, especially in the context of other serious issues South Africa is facing, such as poverty alleviation. Policies implemented to mitigate climate change might increase negative health affects due to unanticipated outcomes (e.g. increased local air pollution), and these indirect consequences must therefore be taken into account when devising mitigation strategies. However, greenhouse gas mitigation policies can also have co-benefits and positive impacts on local air pollution. An evidence-based approach that takes into account greenhouse gas emissions, ambient air pollutants, economic factors (affordability, cost optimisation), social factors (poverty alleviations, public health benefits), and political acceptability is needed tackle these challenges. A proposal is made that use of an integrated climate/air pollution techno-economic optimising model, such as the Greenhouse Gas and Air Pollution Synergies (GAINS) model, may provide a rational decision support tool to guide policy makers into effective strategies for combined Climate Change and Air Quality mitigation measures. (C) 2015 Elsevier Ltd. All rights reserved.