Biodiversity is the cornerstone of the diverse services of ecosystems and the basis for people's well-being. The oceans are the repository of global biodiversity. In 2022, The Kunming-Montreal Global Biodiversity Framework was adopted during the 15th meeting of the Conference of the Parties of the United Nations (UN) Convention on Biological Diversity (CBD). A significant component of this historic framework is the ambitious "30x30" goal, which calls for effective conservation and management of at least 30% of the world's lands, inland waters, coastal areas, and oceans by 2030. With less than 10% of the world's oceans currently protected, the future holds numerous challenges in achieving the "30x30" goal collectively. In 2023, after 20 years of negotiations, the UN General Assembly reached a consensus on the adoption of The Agreement under the UN Convention on the Law of the Sea (UNCLOS) on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction (BBNJ Treaty). These milestones signify a major transformation in global ocean governance where marine biodiversity conservation has become one of the core issues. As the global ocean governance is currently undergoing systematic changes, China should seize the opportunity and plan a path to achieve deep participation in the global marine biodiversity conservation. To address this issue, we review the current global ocean governance mechanism and the development of marine biodiversity conservation issue through a retrospective analysis of key events. On the basis of the legal constraints of UNCLOS and CBD, a series of international conventions and rules have been developed by different parties and organizations for the protection of specific marine areas, marine ecosystems, flagship species, and fishery resources. Over the past two decades, under the leadership of the UN and with the participation of a number of international agencies, nongovernmental organizations, governmental departments, and scientists from various countries, a series of important surveys and comprehensive assessments of global biodiversity (including marine biodiversity) have been performed to provide a scientific basis for the initiative and implementation of the UN global governance program. These global initiatives include the UN 2030 Agenda, the 2021-2030 UN Decade of Ocean Science for Sustainable Development, and the UN Decade on Ecosystem Restoration. As summarized in representative assessment reports, the health of marine ecosystems and biodiversity have been continuously decreasing. As much as 40% of the world's oceans are strongly affected by four major drivers, namely, overfishing, habitat loss, climate change, and environmental pollution. Currently available marine-protected areas have low coverage of species ranges or ecoregions and are not sufficiently effective. Challenges to achieving global marine biodiversity conservation include uncertainties and tipping points in marine ecosystems under global change, conservation of biodiversity in non-jurisdictional areas and jurisdictional governance, and planning for highly connected marine ecological networks. In the future, with the implementation of the "30x30" target and the BBNJ Treaty, how to equitably achieve the conservation and sustainable use of biodiversity in marine areas beyond the limits of national jurisdiction, as well as the equitable sharing of the benefits of biological resources (including genetic resources), will be a focal point of global oceans' governance. In the face of the international situation and national needs, guided by the concept of ecological civilization, China should initially accelerate its own capacity-building and improve the autonomy, intelligence, and internationalization of marine science and technology innovation. Such advancements will support China's in-depth participation and leadership in global ocean governance while delivering scientific and technological support, as well as China's sustainable development solutions.
