Accelerating rates of change in ecosystems are associated with changing climate and land use; mobilization of nutrients and other biologically active chemicals; harvest of natural resources; and trends in many other environmental drivers. Against this backdrop of global change, abrupt and massive shifts at particular sites or even across regional ecosystems are increasingly observed. Abrupt changes remain difficult to anticipate, and many remain challenging to explain after the fact. In this session, the rich set of field studies that document causes and consequences of abrupt changes in diverse ecosystems evokes several broad questions. Are abrupt changes in ecological systems becoming more common? If so, are new mechanisms of abrupt change arising, are familiar mechanisms emerging more frequently or in more places, or do new and familiar mechanisms both contribute? If the resilience of the biosphere is changing, what are the consequences for natural capital and human livelihoods? Is the monitoring, informatics, and modeling capacity required to address these questions in place? The urgency to understand and anticipate abrupt ecological changes in the years and decades ahead suggests a synthetic and visionary research agenda should be a high priority for ecological science.
Results/Conclusions
Science has well-substantiated theories and evidence for many types of abrupt change in ecosystems. However, complex cases that may not fit the mold of past research are emerging as the incidence of abrupt changes increases, especially as the mean and variability of environmental changes move outside historical ranges. Data are often incomplete, and observers may realize too late that key variables were unmeasured. It can take years of long-term observation, cross-system comparison, or whole-ecosystem experiments to discriminate among models that have critically different implications for managing living resources. Yet, the urgency of on-going change places a high priority on understanding the mechanisms and combinations of conditions that produce abrupt change. Ecologists can help solve these emerging challenges by (1) increasing collaborations of theorists and field scientists to understand trends, typologies, and scales of abrupt ecosystem changes; (2) applying our imaginations to envision and understand novel changes in ecosystems; (3) promoting multi-pronged approaches that combine empirical observations through time and across space, experiments focused on understanding mechanisms underpinning change, and models to project plausible outcomes; and (4) portraying accurately the uncertainty for natural capital and human livelihoods in a time of rapidly changing resilience of our planet.