This chapter reviews the history of the IPCC’s efforts to achieve and maintain policy relevance while remaining policy-neutral and staying far away from ‘policy prescriptiveness’. The chapter argues that the boundaries between policy relevance, neutrality and prescriptiveness are a practical achievement – they must be constantly negotiated as the science and politics of climate change evolve. The chapter uses historical case studies to illustrate this point, such as the controversy over the so-called ‘burning embers’ diagram. It ends by discussing recent debates about the IPCC’s new role in the post-Paris Agreement policy landscape. While IPCC actors call for greater policy relevance, observers and critics contend that the IPCC will always and inevitably be policy-prescriptive, even if on a tacit and unintentional level. Achieving even greater policy relevance may therefore mean jettisoning or modifying the aspiration to be policy-neutral.

This chapter outlines the process of IPCC report writing and discusses, through specific examples, how these reports are produced within, and shaped by, political and scientific contexts. The IPCC produces Assessment Reports, Special Reports, and Methodological Reports, which are central to the institution’s operations and perceived impact. There are also sub-elements of these reports – Summary for Policymakers and Technical Summaries – which fulfil important standalone roles. The process of writing these reports is well-institutionalised and involves maintaining a balance between scientific credibility and policy relevance. The reports produced are therefore accountable to, and co-produced with, scientific and policy communities. The chapter shows how the framing of IPCC reports has changed over time and continues to evolve. This also raises questions about the future of IPCC reports in relation to IPCC processes and in response to diversifying audiences and new media.