This paper focuses on the complex, entangled relationships between research and policy and suggests this is a very important topic in the contemporary era of so-called, 'evidence-based' or 'research-based' policy in education. The paper argues that we can only ever have 'evidence-informed' and 'research-informed' policy because all policy is an admixture of facts (research), politics (discourses, values, ideologies) and professional knowledges, a position readily apparent in respect of ESE and broader climate policy. The paper also argues that post-truth contexts and the politics of affect provide a significant backdrop to research/policy relationships with specific salience in respect of environmental and sustainability education (ESE) research and policy, given the conflictual politics surrounding this domain. The distinction between research for and of policy is used analytically in the paper. While research for policy, often conducted by private consultancies, might have a more direct and immediate impact on policy, it is suggested that research of policy, often conducted by academic researchers, and indeed research of a critical kind, potentially can have long-term impact, affecting the assumptive worlds of policy makers, often in unacknowledged ways. Globalization has resulted in the global circulation of policy ideas and thus research can affect policy at varying levels in contemporary policy processes of the restructured/rescaled state. Some consideration is also given to the rise of big data and policy as numbers. The paper discusses implications of such developments for considerations of research/policy relationships, particularly in relation to ESE. The paper concludes by suggesting the current climate emergency demands activist research and researchers in the ESE domain and also activist teachers and students.