National and international policy‐makers have addressed threats to environmental sustainability from climate change and other environmental degradation for over 30 years. However, it is questionable whether current policies are socially, politically, economically, and scientifically capable of adequately resolving these threats to the planet and living organisms. In this paper we theorize and develop the concept of a “policy assemblage” from within a new materialist ontology, to interrogate critically four policy perspectives on climate change: “liberal environmentalism”; the United Nations policy statements on sustainable development; “green capitalism” (also known as “climate capitalism”) and finally “no‐growth economics.” A materialist analysis of interactions between climate change and policies enables us to establish what each policy can do, what it ignores or omits, and consequently its adequacy to address environmental sustainability in the face of climate change. None, we conclude, is adequate or appropriate to address climate change successfully. We then use this conceptual tool to establish a “posthuman” policy on climate change. Humans, from this perspective, are part of the environment, not separate from or in opposition to it, but possess unique capacities that we suggest are now necessary to address climate change. This ontology supplies the starting point from which to establish sociologically a scientifically, socially, and politically adequate posthuman climate change policy. We offer suggestions for the constituent elements of such a policy.