Résumé
The Belmont Forum fosters transdisciplinary sustainability research through its Collaborative Research Actions (CRAs). In 2018, the Oceans CRA was launched to advance knowledge and solutions for sustainable use of ocean resources, resulting in 13 multilateral projects involving researchers and societal actors from 16 countries. Building on these achievements, Ocean 2 was developed during the final phase of the Oceans CRA and endorsed as a contribution to the UN Decade of Ocean Science for Sustainable Development (2021-2030). Ocean 2 expands the scope of its predecessor by emphasizing biodiversity conservation, nature-based solutions, the integration of biodiversity with climate and ocean dynamics in line with nexus approaches sensu IPBES and the Convention on Biological Diversity’s 2050 Vision of “Living in Harmony with Nature,” and the attention to ethics, governance, and the use of scenarios as tools to foresee desirable futures for ocean biodiversity in relation to society. Here we describe the co-design process that led to the formulation of Ocean 2, an initiative of the French Alliance for Environmental Research refined through eight scoping workshops held worldwide in 2024. Two complementary formats—hybrid sessions at international conferences and fully online workshops—were used to engage researchers and societal actors across disciplines, sectors, regions and world-views. Input was synthesized to identify central themes, which informed the final Call text adopted by Belmont Forum members in 2025. The Ocean 2 CRA call was opened in June 2025, with applications due in March 2026. By combining structured co-design, global outreach, and integration with the Ocean Decade’s 10 Challenges, Ocean 2 is a step towards building inclusive, transdisciplinary, and solution-oriented research agendas for the ocean we want.