Humanity faces three epoch-defining environmental problems: climate, extinction and pestilence. Our climate is changing at a rate that is unprecedented and, if unchecked, disastrous. Species are disappearing hundreds or thousands of times faster than normal. COVID-19 has wreaked social and economic havoc but is merely the latest of a blossoming production line of emerging infectious diseases, many of which have the potential to be far worse. At the heart of all three problems is an ancient habit we have never been able to shake: eating animals. This paper explores the role this habit plays in the generation of these problems and the role abandoning it can play in the solution.