by Smrutishree Lenka, Krushna Chandra Gouda, Rani Devi & T. S. Mohan 

This study evaluates future changes in Indian summer monsoon (ISM) rainfall, seasonal duration, and impact of pre-monsoon temperature rise using the simulations from twelve CMIP6 climate models under multiple Shared Socioeconomic Pathways (SSPs). Analysis indicates that historical simulations (1951–2014) from the models, assessed against India Meteorological Department (IMD) gridded observational data led to the selection of five models that closely capture observed monsoon rainfall patterns within one standard deviation. Analysis indicates that, over central Indian region extreme rise in temperature > 5.4 °C accompanied by a 3.2% increase in monsoon rainfall in the far-future (2075–2100) scenario. Further, the ISM length at each grid point computed using a novel algorithm from the historical analysis reveals that Northwestern India experiences a comparatively shorter monsoon season. Projections under more intense emission scenarios like SSP-370 and SSP-585, exhibits the ISM-length .decrease by nearly 7–8 days over the next 76 years. At the same time, future projections in indicate a substantial rise in ISM rainfall under high-emission scenarios, suggesting an intensification of the monsoon despite a shortened duration. This paradox is closely linked to increasing pre-monsoon temperatures, which enhance atmospheric moisture-holding capacity and lead to more compound extreme events. The study quantifies the sensitivity of monsoon rainfall to pre-monsoon warming, highlighting spatial variability in rainfall response per 1 °C temperature increase and found that that pre-monsoon temperatures continue to be on the higher side in both SSP5-8.5 and the far-feature scenarios. These findings indicate a growing risk of hydro-meteorological extremes such as heatwaves and urban flooding, especially under high-emission futures like SSP3-7.0 and SSP5-8.5. The projected combination of shorter rainy seasons and more intense rainfall events underscores the urgent need for targeted adaptation and resilience planning across sectors and regions in India.

Source: https://doi.org/10.1007/s00382-025-07923-1