Compound drought-heatwave events accelerate the potential risk on rice yield over Southeast Asia

Abstract

The agricultural industry in Southeast Asia (SEA) is seriously threatened by weather and climate extremes, of which compound drought–heatwave (CDHW) events are especially detrimental. Using Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) and Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model ensembles, we investigated the projected changes in CDHWs and rice yield in SEA, and further examined the potential driving factors behind the impacts of CDHWs on yield. Results indicate a projected 550 % increase in the annual occurrence of CDHWs, which correlates significantly with a 27 % decrease in rice yield under the SSP5–8.5 scenario at the end of the 21st century. Vapor pressure deficit (VPD) emerges as a major factor contributing to the reduction in rice yield during CDHW events, with its impact for the southern Indochina Peninsula (SICP) being significantly greater than that of evapotranspiration, and slightly higher for Sumatra. Higher temperatures and lower atmospheric vapor during a CDHW leads to water loss from rice plants, ultimately affecting crop growth and reducing yield. To protect local food security from the adverse effects of CDHWs, it is crucial to implement comprehensive measures to mitigate against heat stress and reduce greenhouse gas emissions at both regional and global levels