The Global Earth System: Past and Present

This book investigates the billion-year takeover of planet Earth by its organisms and ecosystems. In this Chapter 10, elements from Chapters 1– 9 are reorganized into a broad picture of the development of the Earth System over billions of years, called The Legend of the Eons. The latter considers successively: the major external and internal abiotic processes that affect the Earth System; the Earth’s acquisition of its physical properties, and their effects on the evolution of the planet; the main steps of biological evolution; the evolution of free oxygen in the Earth’s environment; and the emergence of negative feedback loops in the Earth System. These aspects are combined to describe the evolution of the Earth System, including the effects of human societies. The chapter then focuses on the Anthropocene, which is the period during which human societies had significant impacts on the Earth System, and examines distant events at the onset of the Anthropocene, followed by the growth of human population and its effects on the environment. The Chapter concludes on examples that explain how, during the second part of the twentieth century, countries acted in concert to reduce or eliminate the causes of large-scale or global environmental disturbances. These examples show that governments took action when scientific evidence and public pressure convinced them to do so. However, many other developing global environmental problems were not addressed in the twentieth century despite mounting evidence that they were building up. The consequences are addressed in Chapter 11.