Increased spread of global flash droughts threatens vegetation productivity resilience

Flash drought (faster-developing drought) has been pervasively intensified, posing detrimental constraints on vegetation productivity. However, the potential expansion of flash droughts from flash drought hotspots to non-hotspots and its associated risks to vegetation productivity remain unknown. Furthermore, the divergence in the underlying drivers governing vegetation productivity responses to flash and slow droughts (slower-developing droughts) is unclear. We quantify the dominant drivers underlying vegetation productivity resilience (the departure of productivity anomalies after drought effect to the long-term mean) to both flash and slow droughts. There exhibits significantly lower productivity resilience to flash drought at flash drought hotspots than non-hotspots (Δ = -0.07 ± 0.02, t = -3.25, p < 0.001). The productivity resilience to flash drought is more sensitive to the same reduction in productivity anomaly and intensified climate stress than slow drought. Carbon dioxide fertilization effect exerts the greatest positive effect on productivity resilience to both flash and slow droughts, although that effect is smaller under flash droughts. Our study underscores the limited global ecosystem resilience to the intensification and spread of flash droughts.