Ecological feedbacks in the Earth System

Ecological feedbacks are fundamental features of the Earth system, affecting physical processes and chemical cycles. Our understanding of the interactions underlying these feedbacks at different spatial and temporal scales and the extent to which feedbacks affect Earth system functioning remains limited. Climate change and other anthropogenic pressures are already negatively affecting ecological processes in marine, freshwater, and terrestrial ecosystems. These will most likely be amplified in the coming decades under our current warming and socioeconomic pathways. The knock-on impacts on ecological feedbacks have the potential to cause rapid perturbations to the Earth system, and may significantly impact the structure and functioning of ecosystems. Yet, the role of our planet's diverse ecological feedbacks in Earth system processes and the impacts of perturbations are major knowledge gaps. Here we review and synthesize current understanding of ecological feedbacks and how they affect physical and chemical processes. We then consider the implications of ecological feedbacks for analyses of anthropogenically-driven change, development of scientific understanding and models, and provision of scientific advice for policymakers. Finally, we identify three priority future research areas for the rapid assessment and integration of ecological feedbacks in Earth system science: (a) including ecological feedbacks in assessments of global change and Earth system models, (b) incorporating ecological feedbacks across scales, and (c) producing projections suitable for policy advice. Overall, this review presents an urgent call to the scientific community for the rapid development of understanding of ecological feedbacks and integrated ecosystem—Earth system research.