Quantifying Impacts of Vegetation Greenness Change on Drought Over Global Vegetation Zones

Abstract Changes in vegetation greenness have altered the regional terrestrial water cycle, yet their influence on drought remains unclear. To quantify the impact of vegetation greenness change on drought across global vegetation zones, this study conducted two simulations with and without linear trends in the Leaf Area Index (LAI), based on the Standardized Precipitation‐Evapotranspiration Index (SPEI) combined with the calibrated Shuttleworth‐Wallace potential evapotranspiration (PET) equation. Results revealed vegetation greening affected 71% of areas, and over 55% of areas experienced increases in PET, decreases in SPEI (indicating drying), and intensified drought conditions. The linear trends in LAI increased potential transpiration but decreased potential soil evaporation in most regions. The changes in drought are determined by the combined effects of these changes in potential transpiration and soil evaporation. This study highlights the critical role of vegetation greenness change in influencing drought.