Extreme Precipitation Risks in South Asia: Future Climate Change Impacts on Population and Cropland

Abstract

Extreme precipitation events increasingly threaten populations and food security across South Asia. Whilst prior research has examined climate change impacts on rainfall patterns, the exposure of populations and cropland to these extremes remains understudied. This study assesses future exposure to extreme precipitation using CMIP6 projections under three Shared Socioeconomic Pathways (SSPs): SSP1-2.6, SSP2-4.5 and SSP5-8.5, for 2021-2060 and 2061-2100, relative to the 1975-2014 baseline. We analyse changes in four key precipitation indices: consecutive wet days (CWD), maximum five-day precipitation (Rx5day), days with precipitation >= 20 mm (R20mm) and total wet-day precipitation (PRCPTOT). Results indicate a significant increase in heavy rainfall and prolonged wet periods, particularly under SSP5-8.5. Compared to the baseline, R20mm is projected to increase by 59.25%, Rx5day by 44.06%, CWD by 9.15% and PRCPTOT by 28.65%. Western India and Pakistan are expected to experience the most pronounced changes, whilst the IGP-including Bangladesh and eastern India-faces the highest exposure due to dense populations and extensive croplands. Population exposure to R20mm is projected to rise by 91.7% under SSP5-8.5 and 103.60% under SSP1-2.6, whilst cropland exposure to Rx5day could increase by 44.44% and 7.12% respectively. These findings underscore the urgent need for targeted adaptation strategies, including improved water management, flood protection and climate-resilient agriculture, to mitigate the escalating risks of extreme precipitation in South Asia.