This book is about the history, present and future of one the most important policy ideas of the modern era - that there is a single, global dangerous amount of climate change. That dangerous amount of climate change is imagined as two degrees centigrade of global warming above the pre-industrial average. Though the two degree idea is based on the value system of elite policy actors, it is been constructed in public discourses as scientific fact. This false representation of the concept undermines opportunities for positive public engagement with the climate policy debate, yet it is strong...