Projecting global soil moisture droughts under climate change: characteristics, agricultural exposure, and adaptation insights

Abstract

The intensification of global warming has increased the severity, frequency, and duration of extreme drought events, posing significant threats to agricultural stability. This study introduces a framework for assessing global agricultural drought impacts under climate change by integrating soil moisture data from 17 CMIP6 (Coupled Model Intercomparison Project Phase 6) models with statistical post-processing techniques. The framework utilises the high-resolution GLDAS (Global Land Data Assimilation System) reference dataset for bias correction and incorporates two SSP scenarios (namely SSP2-4.5 and SSP5-8.5, where SSP stands for Shared Socioeconomic Pathways) to provide a comprehensive evaluation of future soil moisture-driven droughts. Performance metrics were applied to evaluate the accuracy of the climate models, and a non-parametric distribution was used to compute the SSMI (Standardised Soil Moisture Index) for past and future droughts using post-processed CMIP6 data. Statistical tests were conducted to validate the SSMI’s suitability for drought assessment. Future drought events were characterised by severity, intensity, frequency, and duration. An index, the Drought Exposure Index (DEI), was used to analyse drought exposure by overlaying land cover data, enabling the assessment of potential agricultural drought impacts under both SSP scenarios. The DEI ranges from 0 to 1, with higher values indicating greater drought exposure and agricultural vulnerability. Results indicate a clear intensification of soil moisture drought characteristics toward mid-century, particularly under SSP5-8.5, with longer drought durations and increased spatial extent across major agricultural regions. Agricultural vulnerability assessments identify regions most at risk, and continental analysis reveals pronounced drying trends in South America, southern Europe, South Asia, and parts of North America. The agricultural exposure assessment shows that cropland areas in these regions face substantially higher drought risk, with the global mean DEI increasing from 0.71 under SSP2-4.5 to 0.78 under SSP5-8.5 by 2050, reflecting a significant rise in exposure under the more extreme emissions scenario. These findings highlight regions where adaptation efforts are most urgently required. Ultimately, this work enhances understanding of the complex interplay between climate change and drought dynamics, offering actionable insights to support sustainable development. By identifying the most vulnerable drought-prone regions, this research provides critical recommendations for long-term soil moisture drought adaptation, sustainable water management, and climate resilience.