Among the 'wicked problems' facing policymakers and voters today, the threat of catastrophic climate change, also called global heating, is so challenging that it was labelled as 'super-wicked'. The scientific evidence is clear-cut, and most of the technologies needed to stabilize the global climate are well understood. But the policy response has been entirely inadequate.To understand the difficulties, we must draw on our understanding of politics, philosophy and economics, grouped together as PPE. These lectures show how the PPE disciplines can be used to improve understanding of the problems and guide a way toward their solutions.The main focus is on the critical economic concept of opportunity cost: The true cost of anything is what you must give up to get it. In a smoothly functioning market, prices determine, and are determined by, opportunity costs. But markets for the emissions that generate global heating do not operate smoothly, if they exist at all. This book explains how policy responses such as carbon taxes and emissions trading markets are products of these 'market failures'.