Oceanography in 2025: Proceedings of a Workshop (2009)

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Integrated Oceanography in 2025 John J. Cullen* Oceanography needs to define its role in a rapidly changing world Rapid technological advances in ocean observation, modeling and information systems provide the potential for nearly limitless expansion of marine research as the field of oceanography emerges from its data- limited foundations. Now, the challenge is to define the best strategies for exploiting new capabilities while justifying the required investments when resources are limited. Oceanographers can address this challenge by conducting their research in a new and much more immediate con- text of science serving society’s need to observe, understand and predict changes in their local, regional and global environment. This leads to a proposal: Oceanography should become part of a profoundly cross- cutting Global Environmental Portfolio that must be developed if human- ity is to meet the challenges of climate change and increasing human impacts on the planet. The ocean environment is under increasing stress. In addition to the threats of greenhouse-gas-driven climate change—rising global sea lev- els, disappearing Arctic sea ice and global ocean acidification—society’s reliance on the ocean for sustenance is increasing, resulting in over- exploitation of marine resources and increased reliance on aquaculture. Meanwhile, marine biodiversity decreases worldwide with uncertain implications. There is also a global migration of the human population to the coast that is putting more pressure on the coastal zone to support * Dalhousie University  

 OCEANOGRAPHY IN 2025 increased commercial and recreational activity while satisfying growing demands on its natural resources, even as levels of pollution rise. Quite simply, the ocean and human society’s relationship with it are changing profoundly and very rapidly; in response, society must develop effective strategies for stewardship and management of the ocean using a multi- disciplinary approach that takes into account the ecosystem’s numerous interconnected components and also the human dimension. To do this oceanography must join with other disciplines and sectors (commerce, management, policy) to become part of an integrated oceans element of an even broader Global Environmental Portfolio. This movement cannot be led by oceanographers, but we can contribute to it. The challenges of climate change and increasing human impacts on the ocean will drive ocean research during coming decades. However, research alone cannot do the job. Ocean researchers must work across disciplines to provide policy makers, and the public they serve, with clear and understandable assessments of the state of the ocean and its sensitiv- ity to climate and human influences in coming decades of change, if not environmental crisis. The challenge extends beyond finding the answers to technical and scientific questions: the results of scientific research must be validated and conveyed to a broad range of users, quickly and effec- tively. New forms of communication will be key—among disciplines, across sectors, and with the public. Rapid and broadly accessible com- munication of the state of the ocean, and its future role in the biosphere, will be a primary justification and goal for ocean research. Longstanding questions about the ocean will be answered Physical forcing of the ocean by weather and climate, the resultant responses of marine food webs, and their combined influences on the chemistry of the ocean and atmosphere, are intimately and inextricably linked. Consequently, the role of the ocean in global climate change, and the effects of climate variability on living marine resources including fisheries, can be understood only by observing, describing and ultimately predicting the state of the ocean as a physically forced ecological and bio- geochemical system. What has been lacking until recently is the capability of integrating the study of physically forced ecosystem dynamics and biogeochemical cycling across scales, from: • The mesoscale (with spatial scales of order 10-100 km and tempo- ral scales of order 10 to 100 days)—on which pelagic ecosystem structure responds to changes in ocean circulation and mixing, •  the regional and seasonal scales—on which relationships To 

JOHN J. CULLEN  between ocean circulation and nutrient distributions determine patterns of primary productivity and fisheries production, •  the basin scale—on which the oceanic inventories of carbon To dioxide and fixed nitrogen, major drivers of climate, are deter- mined over centuries and longer. The missing element has been the capability for vertically resolved observations of physical forcing and ecological-biogeochemical responses in the ocean interior (e.g., nutrients, oxygen, components of the plankton and indicators of their physiological status) to describe how submesoscale processes contribute to critically important mesoscale variability. By 2025, this capability will be mature (deployed on gliders and profilers, and complemented with direct observations of genes and gene expression), and years of data from across broad expanses of ocean will be available. These observations will form the link between detailed oceanographic process studies, surveys using advanced biogeochemical analyses, and paleoceanographic reconstructions of the relationships between climate and ocean biogeochemistry. In 2025, we will have the data to test com- prehensively the 20th century hypotheses about how ocean systems work (e.g., the influences of environmental variability on pelagic food web structure), and we will certainly develop new hypotheses to explain pre- viously unobserved phenomena. Marine systems will be much more predictable Next-generation numerical models will directly incorporate interdis- ciplinary data from ocean observing systems (satellites, gliders, profilers, moorings) to guide forecasts of a broad range of state variables (concen- trations of nutrients, oxygen and different components of the plankton, including some species). In addition, the models will assimilate, directly from sensors, information on biological and chemical rate processes, including photosynthesis and a range of biochemical transformations. Measurements of inherent optical properties will provide quantitatively grounded proxies for physical, chemical, and biological constituents as well as some rate processes. We will thus be able to predict the variability of key physical, chemical, and biological properties and processes, with measurable skill. But we will never be able to describe fully the complex- ity of ocean ecosystems. Importantly, by 2025 we will appreciate the limits to predictability of ocean ecology on scales from days to years. This will be fundamental to our evaluation of predictions of changes for decadal time scales and longer, which no doubt will become increasingly important as society grapples with environmental challenges in a rapidly changing world.