Warming accelerates global drought severity

[Data availability] The high-resolution SPEI datasets52, developed using the Standardized Precipitation Evapotranspiration Index (SPEI)31, are freely accessible through the Centre for Environmental Data Analysis (CEDA) at https://doi.org/10.5285/ac43da11867243a1bb414e1637802dec and on JASMIN at /badc/hydro-jules/data/Global_drought_indices. The CHIRPS data can be accessed via the Climate Hazards Group (CHG) at https://www.chc.ucsb.edu/data/chirps/ (ref. 40). The MSWEP precipitation dataset is available from the GloH2O website at https://www.gloh2o.org/mswep/ (ref. 41). The hPET dataset is hosted by the University of Bristol at https://data.bris.ac.uk/data/dataset/qb8ujazzda0s2aykkv0oq0ctp (ref. 43). The AED data from GLEAM can be accessed at https://www.gleam.eu/ (ref. 42). The CRU-TS precipitation and AED datasets are available through CEDA at https://data.ceda.ac.uk/badc/cru/data/cru_ts/cru_ts_4.08/ (ref. 50). The ERA5 dataset is available for download from the Copernicus Climate Change Service’s Climate Data Store at https://cds.climate.copernicus.eu/datasets (ref. 5

[Code availability] This study utilized the SPEI code to calculate drought indices. The SPEI code is publicly available on GitHub at https://github.com/sbegueria/SPEI/. For trend analysis, the Trend package in R was used, which is publicly available at https://github.com/cran/trend. The code used to develop the global SPEI datasets, perform the trend tests and produce the figures is available on Zenodo at https://doi.org/10.5281/zenodo.15073433 (ref

Drought is one of the most common and complex natural hazards affecting the environment, economies and populations globally1,2,3,4. However, there are significant uncertainties in global drought trends4,5,6, and a limited understanding of the extent to which a key driver, atmospheric evaporative demand (AED), impacts the recent evolution of the magnitude, frequency, duration and areal extent of droughts. Here, by developing an ensemble of high-resolution global drought datasets for 1901–2022, we find an increasing trend in drought severity worldwide. Our findings suggest that AED has increased drought severity by an average of 40% globally. Not only are typically dry regions becoming drier but also wet areas are experiencing drying trends. During the past 5 years (2018–2022), the areas in drought have expanded by 74% on average compared with 1981–2017, with AED contributing to 58% of this increase. The year 2022 was record-breaking, with 30% of the global land area affected by moderate and extreme droughts, 42% of which was attributed to increased AED. Our findings indicate that AED has an increasingly important role in driving severe droughts and that this tendency will likely continue under future warming scenarios.

We acknowledge the financial support provided by the UK Foreign, Commonwealth and Development Office (FCDO, grant number 201880) and the UK Natural Environment Research Council (NERC, grant number NE/S017380/1). We thank the Centre for Environmental Data Analysis (CEDA, https://www.ceda.ac.uk/) for hosting the global drought datasets.

Peer reviewed