Estimates of anthropogenic carbon uptake from four three-dimensional global ocean models

James C. Orr, Ernst Maier-Reimer, Uwe Mikolajewicz, Patrick Monfray, Jorge Louis Sarmiento, J. R. Toggweiler, Nicholas K. Taylor, Jonathan Palmer, Nicolas Gruber, Christopher L. Sabine, Corinne Le Quéré, Robert M. Key, Jacqueline Boutin

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246 Scopus citations


We have compared simulations of anthropogenic CO 2 in the four three-dimensional ocean models that participated in the first phase of the Ocean Carbon-Cycle Model Intercomparison Project (OCMP), as means to identify their major differences. Simulated global uptake agrees to within ±19‰, giving a range of 1.85±0.35 Pg Cyr 1 for the 1980-1989 average. Regionally, the Southern Ocean dominates the present-day air-sea flux of anthropogenic CO 2 in all models, with one third to one half of the global uptake occuring south of 30°S. The highest simulated total uptake in the Southern Ocean was 70‰ larger than the lowest. Comparison with recent data-based estimates of anthropogenic CO 2 suggest that most of the models substantially overestimate storage in the Southern Ocean; elsewhere they generally underestimate storage by less than 20‰. Globally, the OCMIP models appear to bracket the real ocean's present uptake, based on comparison of regional data-based estimates of anthropogenic CO 2 and bomb 14C. Column inventories of bomb 14C have become more similar to those for anthropogenic CO 2 with the time that has elapsed between the Geochemical Ocean Sections Study (1970s) and World Ocean Circulation Experiment (1990s) global sampling campaigns. Our ability to evaluate simulated anthropogenic CO 2 would improve if systematic errors associated with the data-based estimates could be provided regionally.

Original languageEnglish (US)
Pages (from-to)43-60
Number of pages18
JournalGlobal Biogeochemical Cycles
Issue number1
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • General Environmental Science
  • Atmospheric Science


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