Increasing Extreme Negative Vegetation Responses to Drought-Related Compound Events

Abstract

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 km² 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 CO₂ 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.