Ecosystems threatened by intensified drought with divergent vulnerability

Global climate change is projected to increase the severity and duration of droughts across many regions of the world, which could push ecosystems across their tipping points. To protect the most vulnerable ecosystems, it is critical to understand if ecosystems are likely to collapse rapidly or have a certain buffer capacity with aggravating drought (as characterized by their onset, duration and severity). However, such ecosystem vulnerability has been rarely characterized. Here, we present a novel, multi-faceted approach to quantify the ecosystem vulnerability and associated impacts of drought characteristics across different ecosystems at the continental-scale in Europe using high spatial and temporal resolution satellite data. We observed substantially different vulnerabilities across ecosystems where the vegetation damage increases with earlier, longer and more intense droughts. In particular, irrigated croplands are under prominently high risk when facing intensified droughts with the shortest delay in response to drought (0.67 times that of other ecosystems) and a fast increase in damage to drought (1.27 times that of other ecosystems). Mixed forests have a prominently low vulnerability in terms of a notably slow increase in damage to drought (0.67 times that of other ecosystems) and a relatively long response time (longer than over half ecosystems). Moreover, the vulnerability of most ecosystems largely increases with increasing drought severity. Consequently, vegetation tends to succumb more quickly to intensified droughts. Our multi-faceted approach to ecosystem vulnerability characterization indicates that under future intensified droughts in the 21st century, the functioning of a vast range of ecosystems will be threatened.