Bin He

Vegetation growth is increasingly threatened by both extreme climate events and anthropogenic disturbances. Although considerable attention has been given to detecting large‐scale vegetation anomalies, comprehensive analyses of the spatiotemporal dynamics of negative extreme anomalies in vegetation growth (NEGs) and their underlying drivers remain limited. Here, we treat NEGs as event‐scale vegetation declines from onset to termination, enabling coherent tracking of vegetation decline events and their associated drivers. Applied to global leaf area index (LAI) data from 2001 to 2024, we find increasing tendencies in both NEG frequency (0.07% year ⁻¹ , p = 0.13) and affected area (394,471 km ² year ⁻¹ , p = 0.04), reaching 39% of the global land surface by 2024. Interannual variations in NEG frequency and affected area show positive associations with annual mean CO ₂ anomalies, which may suggest a potential influence on the stability of the terrestrial carbon sink. Coincidence analysis further indicates that drought‐related events dominate globally: single‐driver drought events, together with drought‐related compound events involving temperature extremes and wildfires, account for 58.5%–59.8% of all NEGs. By the end of the 21st century, up to 50.8% of the global land surface is projected to experience NEGs annually under the high‐emission scenario, approximately 1.6 times the simulated historical level. These findings highlight the urgent need for climate mitigation to reduce the intensification of compound climate extremes and underscore the importance of understanding how these events may destabilize ecosystems and amplify climate feedbacks in a warming world.

With global warming, rising atmospheric vapor pressure deficit (VPD) has emerged as a critical driver of vegetation productivity and the terrestrial carbon sink. Yet, the thresholds beyond which VPD constrains tree growth remain poorly quantified. Using 2,953 tree-ring sites and combining generalized additive models with threshold regression models, we demonstrate that growth-related VPD thresholds are widespread. Approximately 63% of the studied species groups exhibited identifiable thresholds, which were generally lower in cool, humid regions and higher in warm, dry environments. For the same tree species occurring under contrasting aridity conditions, thresholds also differed substantially. As VPD has risen, the proportion of sites exceeding these thresholds has increased rapidly since about 1970 and is projected to rise further under different emissions scenarios. Under SSP5-8.5 in particular, approximately 79.8% of the sites are projected to be exposed to VPD above their thresholds by the end of the century. Although potential upward threshold shifts associated with acclimation or adaptation could partly reduce future exceedance, this buffering effect becomes increasingly limited under stronger climate forcing. Without effective climate mitigation, rising VPD will increasingly exceed the tolerance thresholds of trees, placing more trees under sustained growth constraints and undermining terrestrial carbon sequestration.