Ecosystem responses to climate change are often assumed to be gradual, yet increasing evidence reveals widespread thresholds, abrupt transitions, and critical shifts across terrestrial ecosystems. Under accelerating climate change and intensifying extremes, ecosystems are approaching – and in some cases have already passed – critical limits beyond which changes in structure, function, and resilience may occur, with important implications for carbon cycling, biodiversity, and climate feedbacks. This session focuses on ecosystem thresholds and critical transitions under climate variability and extremes. We welcome studies that identify, quantify, and explain changes in ecological processes, including productivity, carbon and water fluxes, disturbance regimes, and ecosystem stability. Relevant mechanisms include thermal thresholds, physiological limits, and ecosystem functional optima, as well as their interactions with drivers such as warming, drought, and land use change. We encourage interdisciplinary approaches combining observations, experiments, remote sensing, and modeling to improve mechanistic understanding and predictive capacity.

• B - Biogeosciences