Risk reduction and adaptation measures remain fragmented, under-scaled, and unevenly distributed across population groups, struggling with the "implementation gap". The knowledge of citizens, communities, and practitioners most exposed to hazards is key to fill this gap, and yet it is treated as a data source or audience to be informed.

We argue that closing the implementation gap requires moving citizen and stakeholder participation upstream. First, moving from data provision and validation towards the co-design of research questions, methods, and assessment frameworks. Second, towards demonstrable uptake of the results in management and policy. Participatory research shows that meaningful engagement is context-dependent, adapting to local histories, capacities, and institutional settings. At the same time, this knowledge needs to resonate with the state of the art in hazard, risk, and climate adaptation science to become actionable. Equally, the value of participation is ultimately decided in policy and planning processes, where scientific evidence competes with political priorities, funding cycles, and institutional mandates.

Following successful editions at previous EGU meetings, this session invites scholars from a wide range of disciplines to contribute work on:
- Co-design of research, where citizens and stakeholders shape questions, priorities, and methods from the outset, like living and real-world labs or transdisciplinary frameworks.
- Integration of citizen and stakeholder knowledge into hazard and risk science: approaches that couple participatory evidence with modelling, remote sensing, impact chains, scenario analysis, or machine learning.
- Evaluation and uptake: methods and case studies that assess participatory processes or outcomes, including the enablers and barriers from co-produced knowledge to policy and planning practice.

We explicitly welcome contributions on understudied hazards (e.g., heat or drought events) and from the Global South and encourage submissions that critically reflect on what makes participation genuine rather than tokenistic from the standpoint of method and practice.