Indian Summer Monsoon Response to Regional Aerosol Emission Changes: RAMIP insights

Anthropogenic aerosol emissions are projected to decline significantly by 2050, with major implications for regional climate. However, unlike greenhouse gases, aerosol impacts are spatially heterogeneous and can influence climate both near emission sources and through remote teleconnections. This is particularly important for the Indian monsoon system, where both local and remote aerosol changes can significantly affect precipitation patterns.

Using the Regional Aerosol Model Intercomparison Project (RAMIP) framework, we examine how local and remote aerosol emission changes influence Indian climate across both pre-monsoon and monsoon seasons. Our analysis employs 10-member ensembles from multiple CMIP6-era models to compare three experiments: Global, South Asian, and East Asian aerosol reductions relative to a high-emission baseline (SSP3-7.0). This experimental design allows us to isolate and quantify the distinct impacts of regional emission changes. Initial results reveal that global aerosol reductions lead to more widespread and intense precipitation changes compared to regional reductions alone, with South Asian aerosol reductions largely mirroring the global response pattern while East Asian emissions play an additional role in modulating monsoon circulation. The Western Ghats and Indo-Gangetic Plains show particularly strong responses. We find significant inter-model diversity in the spatial patterns and magnitudes of these changes, highlighting key areas of uncertainty in aerosol-monsoon interactions. Through detailed analysis of circulation patterns and moisture transport, we investigate the mechanisms driving these precipitation responses and their implications for future climate projections.

Our findings provide insights into the complex relationship between regional aerosol emissions and monsoon dynamics, with important implications for both climate prediction and air quality management in South Asia.