How are governance objects produced in international environmental governance and what role does expertise play in their production? This thesis addresses this question by using the international policy field “climate change loss and damage” in the United Nations Framework Convention on Climate Change (UNFCCC) as an illustrative case study. Empirical data was generated through ethnographic immersion in the UNFCCC’s governance cycle between 2018 and 2021, which includes 62 semi- structured interviews. Departing from the theoretical lens of “co-production”, a concept arguing that knowledge and policy are produced through a co-constitutive process, I develop analytical steppingstones to explore the production of loss and damage. The empirics are presented in three chapters. The first chapter explores the context in which loss and damage policy is produced. I analyse how stakeholder access and engage in four key sites: the Conference of Parties, the intersessional meetings of the Subsidiary Bodies, the meetings of the Executive Committee (ExCom) of the Warsaw International Mechanism (WIM), and the meetings of the WIM ExCom’s expert groups. Institutional norms and structures shape stakeholder access and interactions, yet stakeholder interactions are more likely at smaller meetings or early in the governance cycle. The second chapter identifies and analyses the manifestation of different loss and damage discourses. Operationalised through the lens of problem formulation, I identify three problematisations where loss and damage is either formulated as a: 1) sustainable development failure; 2) a scientific-technological problem; and 3) a climate (in)justice. While all three d problematisations manifest within the UNFCCC, the scientific-technological problematisation dominates the policy field. The final chapter explores the institutional role of expertise in producing the loss and damage object. By analysing expert recruitment processes and the establishment and composition of the loss and damage expert groups, I find that experts are cherry-picked to meet specific knowledge needs while fitting the organisational structure. This thesis provides important theoretical arguments and empirical evidence concerning the production of governance objects and the use of expertise in such production.