Advancing participatory modelling for climate policy assessments: toward policy-relevant, conversation-driven climate-economy modelling

Participatory approaches to integrated assessment modelling seek to bring a more diverse range of views into the modelling process, to build a better understanding of the societal context while supporting more inclusive and fairer decision-making. This need for co-creation reflects a growing trend towards societally engaged and action-oriented research across sustainability science. Efforts to integrate stakeholder inputs in IAM-based research to strengthen legitimacy and transparency of the scientific process and the desirability of its results have remained sparse, with participation often limited to top-down formats in which stakeholders are consulted but rarely able to directly shape choices, outputs, or policy prescriptions. Furthermore, there has been little practical how-to guidance for well-structured participatory IAM processes in a domain that has long acknowledged the added value. Any such process should go beyond well-structured procedures and offer flexibility to quickly adapt to a changing policy landscape and thus to shifting stakeholder priorities.We designed and implemented a participatory process intended to support acceptable, robust, and durable transition strategies, while strengthening trust between modelling researchers and stakeholders. The process was designed to produce outputs that are intelligible in terms of real-world implications and actionable in terms of concrete policy recommendations. In practice, the process began by scoping and prioritising relevant stakeholder groups and policy questions; it then engaged stakeholders in co-designing the analytical approach used to address these questions; interim results were iteratively refined based on stakeholder feedback; and dedicated discussions supported shared interpretation of findings, which were distilled into policy briefs.A key lesson from implementing this multi-stage process was the overly thematic structure: framing exchanges around broad “climate and energy transition” topics often diluted sector-specific dynamics and actionable insights. Going forward, engagement could be organised around key drivers and barriers within each sectoral system (e.g., infrastructure and technology constraints, investment and competitiveness, regulatory bottlenecks, distributional impacts, and feasibility). To operationalise this shift, we propose a re-design of the participatory approach into iterative sectoral conversations that enable continuous exchange between the research process and relevant international debates, drawing on prior experience with knowledge co-production and multidisciplinary transition research and aligning with established scholarship on knowledge co-production for sustainability research. The participation proceeds along two integration tracks: (i) interdisciplinary synthesis linking country-level sectoral findings with global-level analysis, and (ii) transdisciplinary exchanges with a small, carefully selected group of international sector experts, complemented by broader expert-facing events.