Ocean Biogeochemistry and the Global Carbon Cycle: An Introduction to the U.S. Joint Global Ocean Flux Study

Abstract

In the early 1980s, ocean scientists were increasingly aware of the importance of biologically active elements, such as carbon, nitrogen and oxygen, in the regulation of climate and its effects on the habitability of the planet. As scientists reviewed details of the processes that control ocean carbon cycling and the links among oceanic, atmospheric and sedimentary carbon pools, it was clear that it was “hard to make the numbers add up” (Brewer et al., 1986). Fluxes of carbon into and out of the ocean were only crudely constrained, and little detail existed on the seasonal, regional and global patterns of carbon uptake and export or the flux of carbon between the ocean and its boundaries. The U.S. Joint Global Ocean Flux Study (JGOFS), a component of the U.S. Global Change Research Program, grew out of the recommendations of a National Academy of Sciences workshop, held in Woods Hole in September 1984. The international program of which it is part was launched three years later under the auspices of the Scientific Committee on Oceanic Research. In 1989, as the first field studies were getting underway, JGOFS became a core project of the International Geosphere-Biosphere Programme. Am ajor ocean flux program was proposed in the U.S. that would include basin-scale process studies, long-term time-series programs and a global survey of carbon dioxide (CO2) in the ocean (see JGOFS Goals below). Extrapolation of results to the global scale would be assisted by the largescale data sets emerging from satellite observations. Advances in numerical and ecological modeling and data assimilation would help us predict the global-scale response of oceanic biogeochemical processes to anthropogenic perturbations. After more than a decade of scientific effort, the success of this study is clearly greater than the sum of its individual parts. With this special issue of Oceanography, we hope to highlight a few of the accomplishments of U.S. JGOFS. The authors were asked to bring to The Oceanography Society audience a synthesis of the changing paradigms of ocean biogeochemistry and its contribution to the global carbon cycle. In this volume, you will see results from the time-series sites near Hawaii and Bermuda, from each of the four major process studies and from the global-scale survey of CO2, conducted in cooperation with the World Ocean Circulation Experiment. The modeling work discussed in this issue has contributed to advances in our understanding of the controls on upper ocean ecosystems and how these might change with future climate scenarios. An early policy of sharing data and rapid and open distribution via the internet has allowed all scientists access to a consistently high-quality database that will be a long-lasting legacy of U.S. JGOFS. Advances in methods highlighted in this issue have