This third edition has been comprehensively updated to reflect the large changes in scientific knowledge and policy debates on climate change since the previous edition in 2009. It provides a concise but thorough overview of the science, technology, economics, policy, and politics of climate change in a single volume. It explains how scientific and policy debates work, outlines the scientific evidence for the reality and seriousness of climate change and the basic atmospheric science that supports it, and discusses policy options and the current state of the policy debate. By pulling these elements together, the book explains why the issue can be so confusing and provides guidance on practical routes forward. Anyone interested in climate change, the global environment, or how science is used in policy debates should read this book. It is the ideal textbook for undergraduate or graduate courses in environmental policy and climate change.