The real threat of climate change is not about temperature, sea levels, wind or fire. It is about food. Due to global warming, the world’s total food supply will reduce to be less than total demand. This will eventually lead to a world war over food and there is a serious possibility that this could occur in this century. By 2010, we were halfway to accumulating in the atmosphere half the greenhouse gas emissions that are likely to tip us into a food war. If global annual emissions continue to increase at current rates, the atmosphere will be ‘full’ by around 2045, and starvation and war will follow. To date, our response has involved more talking than serious action, and while we have begun to make some good changes, they are at far smaller scale than required. However, we can choose to live well and soon with zero emissions, and we can prosper while we do so. This book is a hopeful one, but our hope is based on the reality of what is possible in the time available, not on dreaming that inaction now will lead to an easier option later.