Evidence is mounting that humanity’s chances of making it through the present century with its civilisation intact are dwindling on account of global warming, biodiversity loss, the unrepentant pursuit of economic growth and the inability to think in the long term. In view of this, it is worth investigating whether downfall is inevitable given the vulnerabilities inherent to human nature and the problems that we have always had in exercising power and discretion wisely. Downfall: Lessons for our Final Century argues that an adverse outcome to the present crisis is practically inescapable because it is too deeply rooted in our historical, psychological, and biological conditioning. While there are admirable stirrings, like the Extinction Rebellion, or the advocacy of Green New Deals, human agency is too fractured to produce the kind of rapid shifts needed to deal with global ecological collapse. Governments declare climate emergencies in one breath and take actions, like continuing to subsidise coal, on the other. In explaining why we are almost certain to fail, Downfall breaks the challenges we face down into seven essays that identify what needs to change if civilisation is to survive.