Assessing the Agricultural Losses over a Rainfed Agricultural System at 1.50C global warming

Rainfed agricultural systems reliant on precipitation-based soil moisture (green water availability) are highly vulnerable to unprecedented temperature and precipitation changes under global warming. However, the relationship between green water and rainfed agriculture varies across regions, significantly influencing the agricultural water system and food security in rainfed areas. This study identifies a causal relationship between regional green water anomalies and rice yield losses at 1.50C global warming level (the global warming target outlined by the Paris Agreement) using a semi-arid global rice exporting watershed in Central India as a testbed. Moreover, the potential of irrigation (blue water availability) in reducing the rainfed agricultural losses was analyzed. The investigation was conducted based on different Coupled Model Intercomparison Project Phase 6 (CMIP6) climate models and a Soil and Water Assessment Tool (SWAT) model under two global warming scenarios (SSP2-4.5 and SSP5-8.5). The results suggest a causal connection between green water anomalies and rice yield losses over the watershed. Projected changes show green water and rice yield may decrease by ~ -20 - +10% and ~ -40 - +5%, respectively. Irrigation positively affects crop yield over the region, but projected changes in blue water (~-60% - +20%) indicate inadequate resources to meet rice yield targets without adaptive measures. Further, the economic losses associated with changes in blue-green water and rice yield will be discussed. This study aids in advancing watershed management strategies to alleviate the impact of global warming on rainfed agricultural system.