This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book provides an accessible and multidisciplinary introduction to the complex human dimensions of geoengineering. It explores both their own and others' framings of climate engineering ideas from a diversity of perspectives. The chapter explains what the effective governance of still emerging geoengineering research and technologies might look like, though these chapters are far from the final word. There have been many attempts to systematise or alter the nomenclature surrounding geoengineering concepts. The chapter presents mounting international concern about anthropogenic climate change, catalysed what has since evolved into an expanding global discussion about geoengineering–the deliberate, large-scale alteration of the Earth's climate system. By the mid-noughties, a clear scientific consensus had emerged on climate change: humans were the primary cause; the risks to humanity were numerous, serious, and escalating; and near-term actions to mitigate the human causes of climate change were essential.