From climates multiple to climate singular: Maintaining policy-relevance in the IPCC synthesis report

The Intergovernmental Panel on Climate Change (IPCC) has provided periodic assessments of the state of knowledge on climate change for 30 years. While these assessments have been central to the making of international climate policy, their relevance has been questioned in the post-Paris era. Can the IPCC's global kinds of knowledge match the demands of an increasingly decentralized and polycentric policy landscape? In this paper we respond to this question by analysing how the IPCC renders a multiple object such as climate change amenable to political intervention. We are particularly interested in the socio-material practices undertaken to translate a complex body of knowledge into a synthesis relevant to climate policy-making. To that end we trace the production of the Synthesis Report (SYR) to the IPCC's 5th Assessment Report (AR5), from scoping, to chapter crafting and final plenary approval, using author interviews, document analysis and observations. We argue that the writing of an IPCC synthesis is a constitutive process that rests upon numerous practices of standardization, aggregation and simplification. While these practices allow the authors to produce a coherent story of global climate change, they are less attuned to demands for geographically-sensitive representations of climate impacts, vulnerabilities and a diversity of response options. As the ways of responding to a changing climate multiply, we argue, so should the understanding and making of policy-relevant knowledge.