we do not know.
In recent years, the ocean and seas have received new prominence in international agendas. To secure a safe planet a priority is the management of the ocean as a “common good for humanity”, which requires smarter observations to assess of the state of the ocean and predictions about how it may change in the future. The ocean is a three-dimensional space that needs to be managed over time (thus four-dimensional), and there is a need for management and conservation practices that integrate the structure and function of marine ecosystems into these four dimensions (Chapter 2). This includes understanding the dynamic spatial and temporal interplay between ocean physics, chemistry and biology. Multiple stressors including climate change, pollution and over-fishing affect the ocean and we need to better understand and predict their interactions and identify tipping points to decide on management priorities (Chapter 3). This should integrate our understanding of land-ocean-atmosphere processes and approaches to reducing impacts. An improved science base is also needed to help predict and minimize the impact of extreme events such as storm surges, heat waves, dynamic sea-floor processes and tsunamis (Chapter 4). New technologies, data handling and modelling approaches will help us to observe, understand and manage our use of the fourdimensional ocean and the effect of multiple stressors (Chapter 5).
Addressing these issues requires a strategic, collective and holistic approach and we need to build a community of sustainability scientists that are able to provide evidence-based support to policy makers within the context of major societal challenges (Chapter 6). We outline new frontiers, knowledge gaps and recommendations needed to manage the ocean as a common good and to develop solutions for a sustainable future (Chapter 7). The governance of sustainability should be at the core of the marine research agenda through co-production and collaboration with stakeholders to identify priorities. There is need for a fully integrated scientific assessment of resilience strategies, associated trade-offs and underlying ethical concepts for the ocean, which should be incorporated into decision support frameworks that involve stakeholders from the outset. To allow the collection, processing and access to all data, a key priority is the development of a business model that ensures the long-term economic sustainability of ocean observations.