There is one single ocean, comprised of interconnecting ocean basins, contains approximately 1.33 billion km3 of water. The heat capacity of water means that the ocean has absorbed about 90% of the additional heat resulting from the increased concentration of atmospheric greenhouse gasses. Furthermore, as the concentration of carbon dioxide has increased in the atmosphere, the concentration in the ocean has also increased resulting in ocean acidification. Other human activities, for example, removal of target species, aquaculture, leisure and recreation, renewable energy production, transport, and communication, are placing direct pressures on the ocean which are resulting in changes, including in biodiversity.

The criticality of the ocean to life on Earth, as well as the wellbeing associated with living near the coast, are now well recognised. Significant, and immediate, interventions are required if tipping points are to be avoided. Management actions are being taken, be they marine protected areas or changes in fishing practices. However, the plan must go further based on various international agreements, including the UN Sustainable Development Goals and the UN Decade of Ocean Science for Sustainable Development (2021 – 2030). By acting now, there is a future when the ocean will be less impacted and the current decline in state is reversed