National Aeronautics and Space Administration

Publication Abstracts

Samara et al. 2026

Samara, A., J.E. Smerdon, R. Seager, and B.I. Cook, 2026: 2021-23: Extreme years of global drought in the context of long- and short-term hydroclimate trends. J. Climate, 39, no. 9, 2075-2096, doi:10.1175/JCLI-D-25-0342.1.

We perform a global assessment of dryness and wetness conditions using an ensemble of observational, satellite-informed, and reanalysis-based soil moisture datasets [soil moisture (SM) Global Land Evaporation Amsterdam Model (SN_GLEAM), SM_ERA5-LAND, and SM_MERRA-2] and drought indices [Palmer drought severity index (PDSICRU) and standardized precipitation evapotranspiration index (SPEI_CRU)]. Over the short term (1982-2023), four or more products consistently identify drying trends in western North America, South America, the Mediterranean, Europe, central Asia, and southern Australia. Wetting trends appear in southern and southeastern Asia, the Sahel, and parts of southern sub-Saharan Africa, while disagreements across products are most evident in central Africa, parts of South America, the Middle East, and Southeast Asia. The year 2023 ranks among the driest on record since 1982: driest in PDSICRU and SM_ERA5-LAND, second driest in SN_GLEAM and SPEI_CRU, and eighth in SM_MERRA-2. A longer-term analysis using PDSICRU from 1903 to 2023 estimates that 2023 was the most severe and spatially extensive drought year in over a century, affecting more than 27% of the global reporting land area. Moreover, the 2021-23 period marks the longest consecutive stretch of extreme drought conditions globally since the early twentieth century. The global patterns of droughts over 2021-23 align with long-term drying trends, consistent with the broader influence of anthropogenic climate change on global hydroclimate. Despite the presence of long-term wetting trends, the wetness of the past decades has not produced events of comparable magnitude to those in the mid-twentieth century, a time that remains unmatched in both the severity and extent of wet extremes.

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@article{sa06500e,
  author={Samara, A. and Smerdon, J. E. and Seager, R. and Cook, B. I.},
  title={2021-23: Extreme years of global drought in the context of long- and short-term hydroclimate trends},
  year={2026},
  journal={Journal of Climate},
  volume={39},
  number={9},
  pages={2075--2096},
  doi={10.1175/JCLI-D-25-0342.1},
}

TY  - JOUR
ID  - sa06500e
AU  - Samara, A.
AU  - Smerdon, J. E.
AU  - Seager, R.
AU  - Cook, B. I.
PY  - 2026
TI  - 2021-23: Extreme years of global drought in the context of long- and short-term hydroclimate trends
JA  - J. Climate
JO  - Journal of Climate
VL  - 39
IS  - 9
SP  - 2075
EP  - 2096
DO  - 10.1175/JCLI-D-25-0342.1
ER  -

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