Will Warming Climate Affect the Characteristics of Summer Monsoon Rainfall and Associated Extremes Over the Gangetic Plains in India?

Abstract

The Indo-Gangetic Plain (IGP) bears great agricultural importance and contributes to a major share of national GDP of India. In present study, a location-specific comprehensive analysis of rainfall extremes over IGP, using second generation CORDEX-CORE simulations in the present and future scenarios (under high emission RCP8.5 scenario) have been performed. Here, the high-resolution CORDEX-CORE simulations with International Centre for Theoretical Physics's regional climate model (RegCM4.7) have been considered for the detailed rainfall characteristics assessment. Twelve thresholds-based climate indices have been analyzed to investigate the characteristics of rainfall extremes during three-time slices: 1986–2005 (historical), 2041–2060 (near future) and 2080–2099 (far future). The RegCM4 projections suggested a substantial decline in mean Indian Summer monsoon rainfall (ISMR) and wet days (rainfall ≥ 1 mm; 7%–14%) over IGP under high-emission RCP8.5 scenario. The contribution of 90th and 99th percentile days and total rainfall on wet days, seems to be get enhanced in future by 14%–35%, which implies the increase and intensification in rainfall extremes over IGP by the end of the 21st century. Further, the decline in ISMR and negligible changes in annual rainfall over IGP suggest the possible shift of monsoon regime during the later months of the year in warming climate. Thus, findings of present study may play a crucial role in predicting the ISMR and rainfall extremes over the IGP. Therefore, it can be useful for scientists and policymakers to plan and implement mitigation strategies.