Assessing the Variability of Aerosol Optical Depth Over India in Response to Future Scenarios: Implications for Carbonaceous Aerosols

Air pollution caused by various anthropogenic activities and biomass burning continues to be a major problem in India. To assess the effectiveness of current air pollution mitigation measures, we used a 3D global chemical transport model to analyze the projected optical depth of carbonaceous aerosol (AOD) in India under representative concentration pathways (RCP) 4.5 and 8.5 over the period 2000-2100. Our results show a decrease in future emissions, leading to a decrease in modeled AOD under both RCPs after 2030. The RCP4.5 scenario shows a 48%-65% decrease in AOD by the end of the century, with the Indo-Gangetic Plain (IGP) experiencing a maximum change of similar to ${\sim} $25% by 2030 compared to 2010. Conversely, RCP8.5 showed an increase in AOD of similar to ${\sim} $29% by 2050 and did not indicate a significant decrease by the end of the century. Our study also highlights that it is likely to take three decades for current policies to be effective for regions heavily polluted by exposure to carbonaceous aerosols, such as the IGP and eastern India. We emphasize the importance of assessing the effectiveness of current policies and highlight the need for continued efforts to address the problem of air pollution from carbonaceous aerosols, both from anthropogenic sources and biomass burning, in India. Air pollution from human activities and biomass burning is a significant issue in India. To understand the efficacy of current efforts, a computer model is used to study the projected levels of carbonaceous aerosols (measured as optical depth) from 2000 to 2100. The results suggest that emissions are expected to decrease after 2030, leading to a drop in modeled aerosol levels. In an optimistic scenario of RCP4.5, aerosol levels could decrease by 48%-65% by the end of the century, with the Indo-Gangetic Plain (IGP) showing the most improvement by 2030. However, in a scenario without any significant measures, aerosol levels may increase by 29% by 2050 and not improve significantly by the end of the century. The study indicates that it might take around 30 years for current pollution control measures to make a noticeable difference in heavily polluted regions like the IGP and eastern India. These findings underscore the importance of evaluating the effectiveness of current policies and the need to address air pollution in India caused by carbonaceous aerosols emitted from both, human activities and biomass burning. Results presented here are crucial for policymakers and the public to understand the progress made and the challenges that persist in combating air pollution over Indian region. The future changes in carbonaceous aerosols carry significant consequences for air quality together with climate change in India Mitigation of carbonaceous aerosols is essential to maximize the co-benefits for future air quality Future shifts in emissions will affect the degree of mitigation needed for anthropogenic sources over India after the year 2030