scPDSI Reveals Future Agricultural Drought Hotspots in Humid Regions

Abstract

Future changes in agricultural drought severity and extent are a paramount concern for global food security. However, projections remain uncertain due to the inherent challenge of consistently defining moisture deficits across varied climatic zones. Prevailing assessments, which predominantly focus on long-term mean moisture trends, often overlook the rapid onset of discrete drought events—especially in humid regions. To bridge this gap, we utilize the self-calibrating Palmer Drought Severity Index (scPDSI), driven by the latest CMIP6 multi-model ensemble, to quantify the future dynamics of droughts in terms of frequency, duration, and intensity. Comparing a historical baseline (1980–2014) with future periods (2015–2049, P1; 2050–2084, P2) under three Shared Socioeconomic Pathways (SSP126, SSP245, SSP585), we project that global croplands will enter mild drought by 2060. Compared to the historical baseline, during the P2 period, drought intensity and duration could increase by up to 29% and 370% under SSP245, while drought frequency is expected to rise by up to 87% under SSP585. Global drought severity is projected to intensify to 1.06 and 1.36 times historical levels in P1 and P2, respectively. Under lower-emission scenarios (SSP126 and SSP245), the average intensity of extreme agricultural droughts decreases by 3%. In stark contrast, under SSP585, drought-affected areas are projected to double, expanding by 9.2-fold for extreme droughts (from 1.4 to 12.5% of global croplands). Notably, our analysis identifies clear “humid-region” hotspots, where drought frequency escalates more sharply, underscoring the emergence of significant agricultural risks in traditionally precipitation-reliant regions.

Keywords

Agricultural drought / Drought severity / Exposure / Self-calibrating Palmer Drought Severity Index (scPDSI) / Trend analysis

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