Global and regional climate impacts of future aerosol mitigation in an RCP6.0-like scenario in EC-Earth

Future changes in aerosol concentrations will influence the climate system over the coming decades. In this study we evaluate the equilibrium climate response to aerosol reductions in different parts of the world in 2050, using the global climate model EC-Earth. The aerosol concentrations are based on a set of scenarios similar to RCP6.0, developed using the IMAGE integrated assessment model and exploring stringent and weaker air pollution control. Reductions in aerosol concentrations lead to an increase in downward surface solar radiation under all-sky conditions in various parts of the world, especially in Asia where the local brightening may reach about 10 Wm−2. The associated increase in surface temperature may be as high as 0.5 °C. This signal is dominated by the reduced cooling effect of sulphate which in some areas is partially compensated by the decreased warming effect of black carbon. According to our simulations, the mitigation of BC may lead to decreases in mean summer surface temperature of up to 1 °C in central parts of North America and up to 0.3 °C in northern India. Aerosol reductions could significantly affect the climate at high latitudes especially in the winter, where temperature increases of up to 1 °C are simulated. In the Northern Hemisphere, this strong surface temperature response might be related to changes in circulation patterns and precipitation at low latitudes, which can give rise to a wave train and induce changes in weather patterns at high latitudes. Our model does not include a parameterization of aerosol indirect effects so that responses could be stronger in reality. We conclude that different, but plausible, air pollution control policies can have substantial local climate effects and induce remote responses through dynamic teleconnections.