Interannual and Interdecadal Wet‐Dry Transitions Over the Past 75 Years

Dry‐wet transition (DWT), denoted as the condition shifting between dry and wet climatic states, are a key manifestation of hydroclimatic nonstationary and pose great challenges to the stability of global water resources and ecosystems. However, their interannual‐to‐interdecadal variability remains poorly understood at the global scale. In this study, we identify global DWT events from 1950 to 2024 and investigate their interannual‐to‐interdecadal characteristics using ERA5‐based land water availability data, defined as annual precipitation minus evapotranspiration. DWT has an average transition time of 5.61 years and exhibits significant spatial heterogeneity, with transition times generally shorter at mid‐to‐high latitudes of the Northern Hemisphere. Over the past 75 years, DWT events have occurred frequently and intensely over northern and eastern North America, northern and central Eurasia, and eastern South America. Compared with dry‐to‐wet events, wet‐to‐dry events occur more frequently, with faster transitions and higher intensities. These contrasting characteristics are most pronounced in the 0°S–30°S latitude band. Globally, excluding Greenland and Antarctica, the affected area of DWT events shows an overall downward trend (−0.56%/10a). Changes in precipitation exert a stronger influence on DWT events than changes in evapotranspiration, in terms of frequency, transition time, and intensity. These findings provide important insights into interannual‐to‐interdecadal DWT events from a land‐surface hydrological perspective, with implications for future hydrological risk assessment under climate change.