Water availability regulates abrupt shifts in global terrestrial vegetation productivity by reducing resilience

Abrupt shifts in vegetation productivity induced by environmental change
profoundly affect ecosystem functions and services, such as carbon
sequestration, biodiversity maintenance, and climate regulation, yet their
long-term global patterns and underlying drivers remain insufficiently
understood. In this study, abrupt shifts in vegetation
productivity were identified using two independent long-term satellite
datasets, and early warning signals were assessed through ecosystem
resilience. The main drivers of resilience decline were further examined
across land cover, climate, and human-activity dimensions. The results
showed that negative abrupt shifts were predominantly concentrated in high
northern latitudes and equatorial regions, and that both negative and
positive abrupt shifts displayed distinct increasing trends after 2002. A
sharp decline in ecosystem resilience was also detected during the
four years preceding abrupt shifts. Changes in water
availability were identified as the primary factor contributing
to the reduced resilience of global ecosystems, as evidenced
by the driver trajectory, generalized additive models, and
convergent cross-mapping methods. This study provides insight
into the pervasive occurrence of abrupt shifts in vegetation productivity
and the discernible impact of climate change. When projecting
vegetation dynamics under future climate change, it is essential to
consider the significant uncertainties associated with abrupt shifts.