Global drought shows no detectable recent acceleration under climate warming

Abstract

Recent studies suggest that warming is accelerating continental drought, but these conclusions rely on drought indices using Penman-type potential evapotranspiration (PET). While Penman-type PET is widely used and may suit non-water-limited or irrigated surfaces, it can overstate evaporative demand at broader spatial scales by neglecting land-atmosphere coupling constraints; energy-based PET formulations can address this limitation. Applying multiple PET formulations to calculate the Standardized Precipitation Evapotranspiration Index (SPEI) over 1981–2024, we show that Penman-type methods artificially inflate PET contributions to SPEI trends, resulting in drying trends at least six times stronger than energy-based SPEIs across drought severity, frequency, and duration. We find no significant acceleration of drought trends across ~99% of quasi-global land area under either PET type. This finding remains robust across centennial timescales (1901– or 1950–2024). Reported drought acceleration therefore largely reflects unconstrained PET methods and imprecise analytical frameworks, rather than a true ecohydrological response to warming, with important implications for climate risk assessment and adaptation planning. No statistically significant acceleration in drought is detected across ~99% of quasi-global land area, according to a study that applied multiple Penman-type and energy-based potential evapotranspiration formulations to Standardized Precipitation Evapotranspiration Index records from 1981–2024.