Early-warning signals of critical transitions in global ecoregions

Terrestrial ecoregions represent coherent ecological units shaped by shared environmental conditions and biological communities. As ecosystems approach critical transitions, their resilience declines, showing slower recovery from perturbations and increasing temporal autocorrelation. Here, we analyze 22 years of global satellite vegetation data to detect early warning signals of structural ecological change across all terrestrial ecoregions. By combining spatial clustering, vegetation trend analysis, and resilience indicators, we identify ecoregions exhibiting both vegetation change and declining resilience. We find that approximately one-quarter of ecoregions, covering over one-third of Earth's land surface, show consistent signals of emerging structural transitions. Many of these occur in regions with low direct human modification, suggesting a strong role for large-scale environmental drivers. The detected patterns reveal increasing internal fragmentation within ecoregions and highlight regions potentially approaching critical transitions. This framework provides a scalable approach for identifying ecosystems at risk and supports targeted monitoring and conservation planning.