Earlier collapse of Anthropocene ecosystems driven by multiple faster and noisier drivers

A major concern for the world's ecosystems is the possibility of collapse, where landscapes and the societies they support change abruptly. Accelerating stress levels, increasing frequencies of extreme events and strengthening intersystem connections suggest that conventional modelling approaches based on incremental changes in a single stress may provide poor estimates of the impact of climate and human activities on ecosystems. We conduct experiments on four models that simulate abrupt changes in the Chilika lagoon fishery, the Easter Island community, forest dieback and lake water quality-representing ecosystems with a range of anthropogenic interactions. Collapses occur sooner under increasing levels of primary stress but additional stresses and/or the inclusion of noise in all four models bring the collapses substantially closer to today by similar to 38-81%. We discuss the implications for further research and the need for humanity to be vigilant for signs that ecosystems are degrading even more rapidly than previously thought. Current models, based on incremental changes in a single stress, have limited ability to anticipate abrupt ecosystem changes due to climate and human activities. Experiments on four models simulating ecosystems with a range of anthropogenic interactions show how much earlier abrupt change can happen.