Sectoral emissions contributions to anthropogenic aerosol scenarios over the Indian subcontinent and effects of mitigation on air quality, climate, and health

Over the last few decades, there have been substantial changes in sectoral anthropogenic emissions over India, modifying the region's air quality and radiation budget. However, these sectoral contributions are still poorly understood. This study attempts to estimate the anthropogenic aerosols and SO₂ emissions from different sectors over the Indian subcontinent and their implications for regional climate and human health using the RegCM4.4 regional climate model and the Greenhouse Gas-Air Pollution Interactions and Synergies (GAINS) global model. We consider current emissions as well as emissions with a mitigation scenario for the year 2030. The RegCM simulations with ECLIPSE v5a as emissions inventory for 2000 and 2015 show high SO₂ emissions from the energy sector, substantially contributing to anthropogenic aerosol optical depth (AOD_anthro) and climate forcing. The residential and transport sectors' imprint on climate forcing is increased in 2015 compared to 2000. Higher AOD_anthro (0.35-0.45) occurrence days substantially decrease under a mitigation scenario by 5-10% over the Indo-Gangetic Plain. In particular, over 5 megacities (Delhi, Kolkata, Mumbai, Chennai, and Bangalore) of India, the concentrations of black carbon, organic carbon, and particulate matter ≤2.5 μm in diameter (PM_2.5) are substantially reduced under the mitigation scenario; however, SO₂ is increased. The reduction of pollutants contributes to significantly reducing life expectancy loss in all cities. This study advocates the need for future emission control policies with a synergy between air quality and climate change.