Remote sensing-based detection of resilience loss in the terrestrial water cycle

In the face of Anthropogenic change, ecosystems globally have shown evidence of resilience loss in the past several decades. By governing key processes in terrestrial ecosystems, the hydrological cycle is critical for Earth system stability. A resilient system is able to retain its function and structure in the face of external perturbations. Changes to driving hydrological variables, i.e., precipitation, evaporation, and soil moisture, are thought to be important drivers of terrestrial ecosystem resilience, and vice-versa through land-atmosphere feedbacks. Resilience has been estimated through time series analysis, where an increase in metrics of system recovery time can signal a loss of system resilience. To date, such methods of resilience analysis have not yet been applied to hydrological variables. As a result, there is limited quantification of the role of the water cycle in Earth system resilience.

Here, using remotely sensed time series data, we employ both early warning signals of resilience loss and indicators of rate-based tipping to asses resilience loss in key hydrological variables at the global scale. In doing so, we present a spatially distributed assessment of global water resilience, highlight regions vulnerable to resilience loss, and provide insights into how water resilience affects terrestrial ecosystem resilience. Changes to hydrological variables can have wide-reaching impacts on ecological (e.g., affecting biodiversity, ecosystem structure and function), and social systems (e.g., affecting crop yields in breadbasket regions). Here, we present a new dimension to the characterisation of regions vulnerable to resilience loss.