Many have claimed that climate change is an imminent threat to humanity, but there is no way to verify such claims. This is concerning, especially given the prominence of some of these claims and the fact that they are confused with other well verified and settled aspects of climate science. This paper seeks to build an analytical framework to help explore climate change’s contribution to Global Catastrophic Risk (GCR), including the role of its indirect and systemic impacts. In doing so it evaluates the current state of knowledge about catastrophic climate change and integrates this with a suite of conceptual and evaluative tools that have recently been developed by scholars of GCR and Existential Risk. These tools connect GCR to planetary boundaries, classify its key features, and place it in a global policy context. While the goal of this paper is limited to producing a framework for assessment; we argue that applying this framework can yield new insights into how climate change could cause global catastrophes and how to manage this risk. We illustrate this by using our framework to describe the novel concept of possible’ global systems death spirals,’ involving reinforcing feedback between collapsing sociotechnological and ecological systems.