SPECIAL ISSUE – JGOFS Ocean Biogeochemistry and the Global Carbon Cycle: An Introduction to the U.S. Joint Global Ocean Flux Study Ken O. Buesseler Woods Hole Oceanographic Institution • Woods Hole, Massachusetts USA In the early 1980s, ocean scientists were increasingly led to some key breakthroughs in our ability to understand aware of the importance of biologically active elements, the dynamics of the dissolved organic carbon pools and such as carbon, nitrogen and oxygen, in the regulation of particulate fluxes from the upper ocean to the depths. climate and its effects on the habitability of the planet. As Common protocols and new chemical standards have scientists reviewed details of the processes that control allowed for accurate comparisons among studies. Within ocean carbon cycling and the links among oceanic, atmos- JGOFS and in the future, new technologies will lead to a bet- pheric and sedimentary carbon pools, it was clear that it ter understanding of episodic and short-term shifts in ocean was “hard to make the numbers add up” (Brewer et al., biogeochemistry and links among physical forcing, biologi- 1986). Fluxes of carbon into and out of the ocean were only cal responses and chemical fluxes on a range of spatial crudely constrained, and little detail existed on the season- scales. al, regional and global patterns of carbon uptake and As we think about the remaining challenges in ocean export or the flux of carbon between the ocean and its biogeochemistry, it is easy to forget how far we have come. boundaries. After eight years' worth of days at sea, covering almost The U.S. Joint Global Ocean Flux Study (JGOFS), a enough miles to circle the globe 16 times, considerable dis- component of the U.S. Global Change Research Program, cussion and hundreds of papers, U.S. JGOFS scientists are grew out of the recommendations of a National Academy confident that we have reduced the uncertainties in our of Sciences workshop, held in Woods Hole in September understanding of the global ocean carbon cycle while gain- 1984. The international program of which it is part was ing a new appreciation of the complexity of biogeochemical launched three years later under the auspices of the systems and their variability over time and space. This has Scientific Committee on Oceanic Research. In 1989, as the been accomplished by many individuals with the help of first field studies were getting underway, JGOFS became a some true community heroes and with steady support from core project of the International Geosphere-Biosphere the National Science Foundation in collaboration with the Programme. National Oceanic and Atmospheric Administration, the Amajor ocean flux program was proposed in the U.S. National Aeronautics and Space Administration, the that would include basin-scale process studies, long-term Department of Energy and the Office of Naval Research. We time-series programs and a global survey of carbon dioxide are pleased to acknowledge the foresight of these agencies (CO2) in the ocean (see JGOFS Goals below). Extrapolation in supporting this work. of results to the global scale would be assisted by the large- We appreciate the chance to present U.S. JGOFS scale data sets emerging from satellite observations. through Oceanography to our fellow oceanographers and Advances in numerical and ecological modeling and data other interested scientists, educators and policymakers. A assimilation would help us predict the global-scale copy of our new U.S. JGOFS brochure, “A New Wave of response of oceanic biogeochemical processes to anthro- Ocean Science,” is included with this issue. Finally, as guest pogenic perturbations. editor, I would like to thank the numerous U.S. JGOFS col- After more than a decade of scientific effort, the suc- leagues who contributed to the scientific insights you are cess of this study is clearly greater than the sum of its indi- reading about here, the authors of these articles and accom- vidual parts. With this special issue of Oceanography, we panying highlights, and the staff of the U.S. JGOFS Planning hope to highlight a few of the accomplishments of U.S. Office in Woods Hole, especially Mardi Bowles and Mary JGOFS. The authors were asked to bring to The Zawoysky, for shepherding this issue to completion with Oceanography Society audience a synthesis of the chang- assistance of the staff of Oceanography. ing paradigms of ocean biogeochemistry and its contribu- tion to the global carbon cycle. Reference In this volume, you will see results from the time-series Brewer, P.G., K.W. Bruland, R.W. Eppley and J.J. McCarthy, 1986: The sites near Hawaii and Bermuda, from each of the four Global Ocean Flux Study (GOFS): Status of the U.S. GOFS major process studies and from the global-scale survey of Program. EOS, 67, 44. CO2, conducted in cooperation with the World Ocean Circulation Experiment. The modeling work discussed in JGOFS Goals this issue has contributed to advances in our understand- ◆ to determine and understand on a global scale the processes ing of the controls on upper ocean ecosystems and how controlling the time-varying fluxes of carbon and associated these might change with future climate scenarios. An early biogenic elements in the ocean, and to evaluate the related policy of sharing data and rapid and open distribution via exchanges with the atmosphere, sea floor and continental the internet has allowed all scientists access to a consistent- boundaries; ly high-quality database that will be a long-lasting legacy of ◆ to develop a capacity to predict on a global scale the response U.S. JGOFS. of oceanic biogeochemical processes to anthropogenic pertur Advances in methods highlighted in this issue have bations, in particular those related to climate change. This article has been published in Oceanography, Volume 14, Oceanography • Vol. 14 • No. 4/2001 reposting, or other means without prior authorization of Number 4, a quarterly journal of The Oceanography Society. The Oceanography Society is strictly prohibited. Send 5 Copyright 2001 by The Oceanography Society. All rights reserved. all correspondence to: [email protected], or 5912 LeMay Reproduction of any portion of this article by photocopy machine, Road, Rockville,MD 20851-2326, USA. This article has been published in Oceanography, Volume 14, Number 4, a quarterly journal of The Oceanography Society. Copyright 2001 by The Oceanography Society. All rights reserved. Reproduction of any portion of this article by photocopy machine, reposting, or other means without prior authorization of The Oceanography Society is strictly prohibited. Send all corre- spondence to: [email protected], or 5912 LeMay Road, Rockville,MD 20851-2326, USA. SPECIAL ISSUE – JGOFS Building the Long-term Picture: The U.S. JGOFS Time-series Programs David M. Karl, John E. Dore and Roger Lukas University of Hawaii • Honolulu, Hawaii USA Anthony F. Michaels University of Southern California • Los Angeles, California USA Nicholas R. Bates and Anthony Knap Bermuda Biological Station for Research • Ferry Reach, Bermuda Introduction Long-term time-series studies are ideally suited for precipitation or evaporation, repositioning of large- investigation of the subtle habitat changes, irregularly scale atmospheric circulation features and the warming spaced stochastic events and complex interdependent associated with rising levels of greenhouse gases are ecological phenomena that affect biogeochemical among the many ecologically relevant physical forces cycles in the world ocean. In 1986, during the early at work in the coupled ocean-atmosphere system. planning stages of what would eventually become the Some climatic perturbations lead to increases in U.S. Joint Global Ocean Flux Study (JGOFS), time- turbulent entrainment or upwelling and thus to a redis- series studies were identified as crucial for assessing tribution of essential macro- and micronutrients in the the baseline or mean states of key parameters in the upper water column. Increased availability of nutrients oceanic carbon cycle and their variability. They were leads, in turn, to increases in primary production and, patterned initially after the VERtical Transport and depending on the scale and duration of the distur- EXchange (VERTEX) time-series study then underway bance, to changes in populations at higher trophic lev- in the northeast Pacific Ocean, but the VERTEX field els and in the export of dissolved and particulate program, which included six cruises and lasted for 18 organic matter. Other perturbations alter near-surface months, proved to be too short in length and the obser- stratification, isolating the upper ocean from the large vations too infrequent to resolve much of the natural reservoir of essential nutrients found in the deeper por- variability in open-ocean ecosystems. This discovery tion of the water column and leading to a variety of presented a scientific and logistical challenge for ecological consequences. The effects of these processes JGOFS planners. on ecosystem structure and functioning cannot be The process-oriented field studies that took place observed during any single oceanographic expedition, during JGOFS captured only part of the variability that no matter how well-planned or fortunate. To study is characteristic of oceanic biogeochemical processes. these aperiodic events and long-term trends, one must They were carried out in specific geographical regions go to sea month after month over many years to to study important physical-biogeochemical interac- observe the natural scales of habitat and ecosystem tions, such as the vernal blooming of the North variability accurately. Atlantic Ocean and the monsoonal forcing of the ecosystems in the surface waters of the Arabian Sea. But capturing the unpredictable, larger-scale and Shifting Ecosystem Paradigms: The Marine lower-frequency climate variations associated with the Microbiological Revolution El Niño-Southern Oscillation (ENSO), Pacific Decadal When planning for U.S. JGOFS began in the mid Oscillation (PDO) and North Atlantic Oscillation 1980s, we thought we had a reasonably comprehensive (NAO) was, for the most part, beyond the scope of understanding of the marine carbon cycle.