The primary focus of my research over the past year was the completion of my textbook cum research monograph on ocean biogeochemistry (Ocean Biogeochemical Dynamics, now in press with Princeton University Press) together with my old post doc and now UCLA faculty member (soon to be ETH faculty member), Nicolas Gruber.  We have reviewed the galley proofs, and the book is scheduled to come out in May.  It is of course difficult to anticipate how it will be received, but there are already quite a few colleagues who have been happily using earlier versions of the book in their courses for some years.

The book represents much more than just a synthesis of our present knowledge and understanding.  One of the reasons it took so long to complete (10 years) is because there was a great deal of new research we needed to do in areas that were just not adequately understood.  I estimate that I published more than two-dozen papers over the past decade that grew primarily out my attempts to fill in the gaps in our understanding.  The gathering of several major new data sets as part of the WOCE and JGOFS programs in the decade of the 1990’s provided a basis for a new look at the field, but much of the analysis of these data had not been done when I started writing during an earlier sabbatical.  In addition, while some areas had a great deal of exciting new research that we could base our book on, no one had successfully attempted to pull all of this together into a new synthesis since Broecker and Peng’s magnum opus of 1982, Tracers in the Sea.  Our ambition was to provide a modern analogue to that wonderful textbook that has served as an introduction for a whole generation of ocean biogeochemists.  We will be delighted if we succeed even partially in accomplishing that goal.

As a result of the exceptional efforts required to finish up the book over the last year, my journal publications dropped from a high of nine achieved in 2004 to one in 2005.  However, I have eight journal articles in press or submitted that reflect the culmination of several ongoing projects that carried over from previous years, as well as reflecting my ever-deepening interest in understanding the critical role of the Southern Ocean in controlling ocean biogeochemistry and its carbon cycle.  These new journal articles can be categorized into three broad areas: (1) ocean biogeochemical processes and modeling, (2) modeling and observational constraints on ocean and land carbon sinks for anthropogenic carbon, and (3) Southern Ocean biogeochemistry and circulation.  Each of these areas is discussed briefly below, with reference to the in press and submitted papers.

Ocean Biogeochemical Processes and Modeling: The Orr et al. (2005) Science paper, my only 2005 journal publication, discusses the impact of ocean acidification by anthropogenic carbon on the depth of the saturation horizon of aragonite, and its likely outcropping at the surface of the Southern Ocean during the middle of this century.  The possible consequences of this are very disturbing.  The in press and submitted articles (1) and (2) by Dunne et al. and Jin et al. present results from our latest efforts to develop new ocean biogeochemistry models.  This is ongoing research aimed at model development with the goal of providing new analyses of the impact of global warming on ocean biology and the ocean carbon cycle.  Article (3) (Behrenfeld et al., submitted) is a byproduct of a parallel effort to develop empirically based ocean ecosystem models based on a new analysis of satellite color observations.

Modeling and Observational Constraints on Carbon Sinks:  A major research directions that my group has taken in the past years is estimation of the magnitude, spatial distribution, and temporal variability of carbon sources and sinks by inverse modeling of atmospheric and oceanic CO2 observations and by evaluation of models with the major new data sets that were gathered by the global surveys of the past decade.  This work culminated during previous years in several papers that converged on an estimate for the oceanic carbon sink of 2.0 ± 0.3 Pg C yr—1 for the 1990’s.  In a series of new papers (references (4) to (6) by Fletcher et al., and Jacobson et al, a and b) my group has explored the implications of this oceanic constraint for our estimates of land carbon sources and sinks.  The submitted papers by Jacobson et al., a and b suggest that the large anthropogenic carbon sink postulated to exist in tropical rain forests is probably a chimera.  The absence of this CO2 fertilization sink has major negative implications for the future growth rate of atmospheric CO2 – mitigation will be much more difficult than had been previously been thought.

Southern Ocean Circulation and Biogeochemistry: Reference (7) (Marinov et al., submitted) demonstrates that there is a clear separation in the Southern Ocean between regions that control the air-sea balance of CO2 (confined primarily to high latitude regions of deep-water formation), and regions that control the return of nutrients from the deep ocean to the surface (lower latitude areas where Subantarctic Mode Water forms; see Sarmiento et al.,, 2004a).  In Mignone et al., in press (reference (9)), we show that major differences in the representation of Southern Ocean circulation previously identified and analyzed by Matsumoto et al. (2004) can be explained as resulting from differences in the representation of wind forcing and mixing in the ocean models.  These differences have major consequences for the rate of CO2 uptake estimated by these models.  We are developing a new ocean model in collaboration with colleagues at GFDL that we hope will provide us with an improved simulation of processes in this region.

Two-Year Bibliography

Books:
Sarmiento, J. L., and N. Gruber, Ocean Biogeochemical Dynamics, Princeton University Press, in press.

Refereed articles:
Doney, S. C., K. Lindsay, K. Caldeira, J.-M. Campin,  H. Drange, J.-C. Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, G. Madec, E. Maier-Reimer, J.C. Marshall, R.J. Matear, P. Monfray, A. Mouchet, R. Najjar, J.C. Orr, G.-K. Plattner, J. Sarmiento, R. Schlitzer, R. Slater, I.J. Totterdell, M.-F. Weirig, Y. Yamanaka, and A. Yool, 2004. Evaluating global ocean carbon models: The importance of realistic physics, Global Biogeochem. Cycles, 18, GB3017, doi:10.1029/2003GB002150.

Edmonds, J., F. Joos, N. Nakicenovic, R. G. Richels, and J. L. Sarmiento, Scenarios, targets, gaps, and costs.  In: The Global Carbon Cycle, ed. C. B. Field and M. R. Raupach, Island Press, Washington, D.C., pp. 77-102. 2004.

Gnanadesikan, A., J. P. Dunne, R. M. Key, K. Matsumoto, J. L. Sarmiento, R. D. Slater, and P, S. Swathi, Oceanic ventilation and biogeochemical cycling: Understanding the physical mechanisms that produce realistic distributions of tracers and productivity.  Global Biogeochem. Cycles, 18, GB4010, doi:10.1029/2003GB002097, 2004.

Greenblatt, J. B., and J. L. Sarmiento, Variability and climate feedback mechanisms in ocean uptake of CO2.  In: The Global Carbon Cycle, ed. C. B. Field and M. R. Raupach, Island Press, Washington, D.C., pp. 257-275, 2004.

Marinov, I., and J. L. Sarmiento, The role of the oceans in the global carbon cycle: An overview.  In: The Ocean Carbon Cycle and Climate, ed. M. Follows and T. Oguz, NATO ASI, Ankara, Turkey, Kluwer Academic Publishers, pp. 251-295, 2004.

Matsumoto, K., J.L. Sarmiento, R.M. Key, O. Aumont, J.L. Bullister, K. Caldeira, J.-M. Campin, S.C. Doney, H. Drange, J.-C. Dutay, M. Follows, Y. Gao, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, K. Lindsay, E. Maier-Reimer, J.C. Marshall, R.J. Matear, P. Monfray, A. Mouchet, R. Najjar, G.-K. Plattner, R. Schlitzer, R. Slater, P.S. Swathi, I.J. Totterdell, M.-F. Weirig, Y. Yamanaka, A. Yool, J.C. Orr, Evaluation of ocean carbon cycle models with data-based metrics.  Geophys. Res. Lett., 31, L07303, doi:10.1029/2003GL018970, 2004.

Mignone, B. K., J. L. Sarmiento, R. D. Slater, and A. Gnanadesikan, Sensitivity of sequestration efficiency to mixing processes in the global ocean.  Energy, 29: 1467-1478, 2004.

Sarmiento, J. L., N. Gruber, M. A. Brzezinski, and J. P. Dunne, High latitude controls of the global nutricline and low latitude biological productivity.  Nature, 427: 56-60, 2004a.

Sarmiento, J. L., R. Slater, R. Barber, L. Bopp, S. C. Doney, A. C. Hirst, J. Kleypas,R. Matear, U. Mikolajewicz, P. Monfray, V. Soldatov, S. A. Spall, and R. Stouffer, Response of ocean ecosystems to climate warming.  Global Biogeochem . Cycles, 18, GB3003, doi:1029/2003GB002134, 2004b.

Orr, J. C., V. J. Fabry, O. Aumont, L. Bopp, S. C. Doney, R. M. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R. M. Key, K. Lindsay, E. Maier-Reimer, R. Matear, P. Monfray, A. Mouchet, R. G. Najjar, G.-K.Plattner, K. B. Rodgers, C. L. Sabine, J. L. Sarmiento, R. Schlitzer, R. D. Slater, I. J. Totterdell, M.-F. Weirig, Y. Yamanaka, and A. Yool, Anthropogenic ocean acidification over the 21st century and its impact on marine calcifying organisms.  Nature, 437: 681-686, 2005.

Articles in press or submitted:
Dunne, J. P., R. A. Armstrong, A. Gnanadesikan, and J. L. Sarmiento, Empirical and mechanistic models for the particle export, Global Biogeochem. Cycles, in press.

Jin, X., N. Gruber, J. P. Dunne, J. L. Sarmiento, and R. A. Armstrong, Diagnosing CaCO3 and opal export and phytoplankton functional groups from global nutrient and alkalinity distributions, Global Biogeochem. Cycles, in press.

Behrenfeld, M., R. O’Malley, D. A. Siegel, C. McClain, J. Sarmiento, G. Feldman, P. Falkowski, E. Boss, and A. Milligan, Climate-driven trends in contemporary ocean productivity, Science, submitted.

Fletcher, S. E., N. Gruber, A. R. Jacobson, S. C. Doney, S. Dutkiewicz, M. Follows, K. Lindsay,  D. Menemenlis, A. Mouchet, and J. Sarmiento, Inverse estimates of anthropogenic carbon uptake, transport, and storage by the ocean, Global Biogeochem. Cycles, in press.

Jacobson, A. R., S. E. Mikaloff-Fletcher, N. Gruber, J. L. Sarmiento, M. Gloor, and TransCom Modelers, A joint atmosphere-ocean inversion for surface fluxes of carbon dioxide: I. Methods and global-scale fluxes, Global Biogeochem Cycles, submitted.

Jacobson, A. R., S. E. Mikaloff-Fletcher, N. Gruber, J. L. Sarmiento, M. Gloor, and TransCom Modelers, A joint atmosphere-ocean inversion for surface fluxes of carbon dioxide: II. Regional results, Global Biogeochem Cycles, submitted.

Marinov, I. A. Gnanadesikan, J. R. Toggweiler, and J. L. Sarmiento, The Southern Ocean biogeochemical divide, Nature, submitted.

Mignone, B. K., A. Gnanadesikan, J. L. Sarmiento, R. D. Slater, Central role of southern hemisphere winds and eddies in modulating the oceanic uptake of anthropogenic carbon,
Geophys. Res. Lett., in press.