Guiding transdisciplinary synthesis processes for social-ecological policy decisions

• Synthesis science can efficiently leverage the process of co-producing policies when it uses transdisciplinary approaches. • Adapting interdisciplinary working group model is pivotal for effectively implementing transdisciplinary synthesis approaches. • We share eight learnings to tackle transdisciplinary syntheses challenges and barriers. • These learnings allowed us to better deal with mismatches in the implementation space between research and practice. Interdisciplinary synthesis research has been promoting significant advances in expanding academic knowledge. However, its application to address social-ecological problems poses challenges, typical of transdisciplinary research and co-production initiatives. Based on the experience of seven working groups from a Brazilian synthesis nucleus dedicated to co-producing social-ecological public policies, we present eight learnings to strengthen transdisciplinary syntheses. Those syntheses require flexibility in the working group dynamics to facilitate collaborative work, with frequent and short meetings held in easily accessible locations (1). They also require flexibility to shape different trajectories, depending on demand urgency, data and knowledge availability (2). Flexibility is also required to adjust to political circumstances, acknowledging that there are trade-offs between responding to urgent political needs and creating novel ideas, knowledge and outputs (3). In addition, the creation of formal institutions, particularly, formal engagement at the science-policy interface (4) and creating formal platforms for disseminating non-academic outputs (5) are key to stimulate the involvement of policy-makers and scientists in collaborative transdisciplinary syntheses. Symmetrical, horizontal interactions within a two-way science-policy linkage (6), alongside collective reflexivity on bridging diverse knowledge, skills, and authorities (7) are crucial for aligning academic knowledge with policy practices. Active involvement of individuals skilled in both scientific research and policy-making, who act as knowledge brokers, further strengthens this alignment. Finally, attention to create positive interactions and transparently communicating help to build trust among participants (8). These adjustments can enhance the potential of transdisciplinary syntheses to generate actionable knowledge at the science-policy interface.