The article discusses the impacts of atmospheric brown clouds (ABCs) on the climate and hydrological cycle in South Asia. Since 1930, emissions of fossil fuel SO2 and black carbon in South Asia have increased by about six times, leading to significant atmospheric concentrations of black carbon and other aerosols. This period also saw a decrease in surface solar radiation, evaporation, and summer monsoon rainfall, along with increased atmospheric stability and reduced sea surface temperature gradients in the Northern Indian Ocean (NIO). The authors conducted ensemble simulations of a coupled ocean-atmosphere model from 1930 to 2000 to understand the role of ABCs in these observed trends. The simulations, which include aerosol radiative forcing from Indian Ocean experiment observations and account for global increases in greenhouse gases and sulfate aerosols, show that the simulated decreases in surface solar radiation, changes in surface and atmospheric temperatures, and reductions in monsoon rainfall are similar to the observed trends. The study also suggests that absorbing aerosols in ABCs may have played a major role in the observed regional climate and hydrological cycle changes, potentially masking up to 50% of the surface warming due to global greenhouse gas increases. The simulations indicate that if current emission trends continue, the subcontinent may experience a doubling of drought frequency in the coming decades.The article discusses the impacts of atmospheric brown clouds (ABCs) on the climate and hydrological cycle in South Asia. Since 1930, emissions of fossil fuel SO2 and black carbon in South Asia have increased by about six times, leading to significant atmospheric concentrations of black carbon and other aerosols. This period also saw a decrease in surface solar radiation, evaporation, and summer monsoon rainfall, along with increased atmospheric stability and reduced sea surface temperature gradients in the Northern Indian Ocean (NIO). The authors conducted ensemble simulations of a coupled ocean-atmosphere model from 1930 to 2000 to understand the role of ABCs in these observed trends. The simulations, which include aerosol radiative forcing from Indian Ocean experiment observations and account for global increases in greenhouse gases and sulfate aerosols, show that the simulated decreases in surface solar radiation, changes in surface and atmospheric temperatures, and reductions in monsoon rainfall are similar to the observed trends. The study also suggests that absorbing aerosols in ABCs may have played a major role in the observed regional climate and hydrological cycle changes, potentially masking up to 50% of the surface warming due to global greenhouse gas increases. The simulations indicate that if current emission trends continue, the subcontinent may experience a doubling of drought frequency in the coming decades.