The Global Earth System: Present and Future

This book investigates the billion-year takeover of planet Earth by its organisms and ecosystems. Concluding Chapter 11 focuses on the Anthropocene, which is the period during which human societies had significant impacts on the Earth System, and considers key events that are happening in the twenty-first century and might happen afterwards. The chapter examines four main global anthropogenic perturbations of the Earth System – climate change, ocean acidification, the loss of biodiversity, and water and food insecurity – in terms of: their general mechanisms; the main human activities that contribute to these perturbations; and their feedbacks into the environment and human activities. It also explains the responses provided by adaptation and mitigation approaches to the ongoing global anthropogenic perturbations of the Earth System. The purpose of adaptation is to manage the unavoidable, and that of mitigation to avoid the unmanageable. Adaptation and mitigation are illustrated using sea level rise as example. The text then looks at possible states of the Earth System beyond the twenty-first century, which are: a long interglacial; a very long interglacial; shifting from the present icehouse conditions to those of a greenhouse; and crossing planetary thresholds, caused by runaway warming. The chapter concludes with considerations of what planet Earth would be without some of the key biological innovations that shaped the Earth System. This leads to the idea that humans should become the stewards of their unique planet without delay, taking into account the imperative need to preserve both its habitability and biodiversity.