In a 2018 special report, the UN Intergovernmental Panel on Climate Change (IPCC) warned of “catastrophic” outcomes unless states were to undertake “unprecedented” action “across all sectors of society” before 2030. This has fueled climate emergency declarations among activist groups and, increasingly, among local, state, and supranational governments. But what exactly counts as a "climate catastrophe," and what does catastrophic climate change portend for contemporary societies? In this talk, I will argue that climate change is or may soon become catastrophic in a pointedly political sense, insofar as it threatens to undermine the material conditions that make justice - and by extension stable (democratic) government - possible. I will then use the lens of catastrophe to bring into focus some pressing questions concerning how to navigate trade-offs between fairness and precautionary efficacy in the design of climate policy, the permissibility of authoritarian climate emergency powers, and the nature and role of climate disobedience.