2021–23: Extreme Years of Global Drought in the Context of Long- and Short-Term Hydroclimate Trends

Abstract 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 (SM GLEAM ), SM ERA5-LAND , and SM MERRA-2 ] and drought indices [Palmer drought severity index (PDSI CRU ) 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 PDSI CRU and SM ERA5-LAND , second driest in SM GLEAM and SPEI CRU , and eighth in SM MERRA-2 . A longer-term analysis using PDSI CRU 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. Significance Statement On a global scale, the years 2021–23 have seen some of the most widespread and severe drought conditions in over a century. By analyzing five major datasets that characterize changes in soil moisture conditions, we find that 2023 was the driest year on record in over 120 years and that 2021–23 was the driest 3-yr period over the same time interval. We show that these recent twenty-first-century extremes are consistent with long-term drying trends and highlight a broad intensification of hydroclimate extremes across much of the globe. While previous work has emphasized regional drought events over shorter intervals, this study uses multiple datasets in a global framework to provide strong evidence that anthropogenic climate change is a key driver of an intensifying global pattern of more widespread and severe drought.