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

• Published in: Global Biogeochemical Cycles
• Main Authors: Orr, J., Maier-Reimer, E., Mikolajewicz, U., Monfray, P., Sarmiento, J., Toggweiler, J., Taylor, N., Palmer, J., Gruber, N., Sabine, C., Le Quéré, C., Key, R., Boutin, J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2001
• Subjects: Southern Ocean
• Online Access: http://hdl.handle.net/11858/00-001M-0000-000E-CE25-6; http://hdl.handle.net/11858/00-001M-0000-000E-CE24-8

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 (OCMIP), as a means to identify their major differences. Simulated global uptake agrees to within +/- 19%, giving a range of 1.85 +/-0.35 Pg C yr(-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 occurring south of 30 degreesS. 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 C-14. Column inventories of bomb C-14 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. [References: 64]