Global maize yield-loss risk under atmospheric–soil moisture compound drought: Roles of phenology and cropping systems

Global maize production is increasingly threatened by drought, yet most assessments rely on single indicators and inadequately account for phenological-stage and cropping-system differences. Here we develop a copula-based Climate-Land Drought Index (CLDI) that integrates the Standardized Precipitation-Evapotranspiration Index (SPEI) and Standardized Soil Moisture Index (SSI) within a common probabilistic framework to characterize water-deficit compound drought. We apply CLDI to characterize drought hazard across global maize-growing regions during 1981–2024 and assess drought-associated yield responses during 1982–2015. CLDI showed consistent associations with vegetation condition and maize yield anomalies, with slightly broader significant yield-association coverage than either single indicator alone. During 1981–2024, 37.1% of global maize-growing areas showed significant drying, accompanied by increasing frequency and persistence of severe-to-extreme drought, especially after 2000. Yield-loss patterns differed across phenological stages: under severe-to-extreme drought, the reproductive stage (S2) was associated with the highest observed yield-loss probability (≈62.5%). Rainfed-dominant systems generally showed higher yield-loss probabilities than irrigated-dominant systems, although these contrasts varied with drought intensity and regional conditions. By integrating compound drought characterization, phenological segmentation, and cropping-system differentiation, this framework supports drought monitoring, identification of high-risk maize-growing areas, and adaptive agricultural water management.