• Aumont, O., and L. Bopp, 2006: Globalizing results from ocean in situ iron fertilization studies. Global Biogeochem. Cycles, 20, GB2017, doi:10.1029/2005GB002591.

    • Search Google Scholar
    • Export Citation
  • Barbero, L., J. Boutin, L. Merlivat, N. Martin, T. Takahashi, S. Sutherland, and R. Wanninkhof, 2011: Importance of water mass formation regions for the air-sea CO2 flux estimate in the Southern Ocean. Global Biogeochem. Cycles, 25, GB1005, doi:10.1029/2010GB003818.

    • Search Google Scholar
    • Export Citation
  • Beckmann, A., and R. Döscher, 1997: A method for improved representation of dense water spreading over topography in geopotential-coordinate models. J. Phys. Oceanogr., 27, 581591.

    • Search Google Scholar
    • Export Citation
  • Blanke, B., and P. Delecluse, 1993: Variability of the tropical Atlantic Ocean simulated by a general circulation model with two different mixed-layer physics. J. Phys. Oceanogr., 23, 13631388.

    • Search Google Scholar
    • Export Citation
  • Böning, C. W., A. Dispert, M. Visbeck, S. R. Rintoul, and F. U. Schwarzkopf, 2008: The response of the Antarctic Circumpolar Current to recent climate change. Nat. Geosci., 1, 864869, doi:10.1038/ngeo362.

    • Search Google Scholar
    • Export Citation
  • Broecker, W., 1991: The great ocean conveyor. Oceanography, 4, 7989.

  • Cadule, P., 2008: Modélisation des interactions entre le système climatique et le cycle du carbone. Ph.D. thesis, University of Paris VI, 375 pp.

  • Crueger, T., E. Roeckner, T. Raddatz, R. Schnur, and P. Wetzel, 2008: Ocean dynamics determine the response of oceanic CO2 uptake to climate change. Climate Dyn., 31, 151168, doi:10.1007/s00382-007-0342-x.

    • Search Google Scholar
    • Export Citation
  • d’Orgeville, M., W. P. Sijp, M. H. England, and K. J. Meissner, 2010: On the control of glacial-interglacial atmospheric CO2 variations by the Southern Hemisphere westerlies. Geophys. Res. Lett., 37, L21703, doi:10.1029/2010GL045261.

    • Search Google Scholar
    • Export Citation
  • Downes, S., N. Bindoff, and S. Rintoul, 2009: Impacts of climate change on the subduction of mode and intermediate water masses in the Southern Ocean. J. Climate, 22, 32893302.

    • Search Google Scholar
    • Export Citation
  • Farneti, R., and T. L. Delworth, 2010: The role of mesoscale eddies in the remote oceanic response to altered Southern Hemisphere winds. J. Phys. Oceanogr., 40, 23482354.

    • Search Google Scholar
    • Export Citation
  • Friedlingstein, P., J.-L. Dufresne, P. M. Cox, and P. Rayner, 2003: How positive is the feedback between climate change and the carbon cycle. Tellus, 55B, 692700, doi:10.1034/j.1600-0889.2003.01461.x.

    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20, 150155.

  • González-Dávila, M., J. M. Santana-Casiano, R. A. Fine, J. Happell, B. Delille, and S. Speich, 2011: Carbonate system in the water masses of the southeast Atlantic sector of the Southern Ocean during February and March 2008. Biogeosciences, 8, 14011413, doi:10.5194/bg-8-1401-2011.

    • Search Google Scholar
    • Export Citation
  • Gregory, J. M., C. D. Jones, P. Cadule, and P. Friedlingstein, 2009: Quantifying carbon cycle feedbacks. J. Climate, 22, 52325250.

  • Ito, T., M. Woloszyn, and M. Mazloff, 2010: Anthropogenic carbon dioxide transport in the Southern Ocean driven by Ekman flow. Nature, 463, 8083, doi:10.1038/nature08687.

    • Search Google Scholar
    • Export Citation
  • Iudicone, D., G. Madec, and T. J. McDougall, 2008: Water-mass transformations in a neutral density framework and the key role of light penetration. J. Phys. Oceanogr., 38, 13571376.

    • Search Google Scholar
    • Export Citation
  • Iudicone, D., K. B. Rodgers, I. Stendardo, O. Aumont, G. Madec, L. Bopp, O. Mangoni, and M. Ribera d’Alcala, 2011: Water masses as a unifying framework for understanding the Southern Ocean carbon cycle. Biogeosciences, 8, 10311052, doi:10.5194/bg-8-1031-2011.

    • Search Google Scholar
    • Export Citation
  • Jackett, D. R., and T. J. McDougall, 1997: A neutral density variable for the world’s oceans. J. Phys. Oceanogr., 27, 237263.

  • Lenton, A., and R. J. Matear, 2007: Role of the southern annular mode (SAM) in Southern Ocean CO2 uptake. Global Biogeochem. Cycles, 21, GB2016, doi:10.1029/2006GB002714.

    • Search Google Scholar
    • Export Citation
  • Lenton, A., F. Codron, L. Bopp, N. Metzl, P. Cadule, A. Tagliabue, and J. Le Sommer, 2009: Stratospheric ozone depletion reduces ocean carbon uptake and enhances ocean acidification. Geophys. Res. Lett., 36, L12606, doi:10.1029/2009GL038227.

    • Search Google Scholar
    • Export Citation
  • Le Quéré, C., and Coauthors, 2007: Saturation of the Southern Ocean CO2 sink due to recent climate change. Science, 316, 17351738, doi:10.1126/science.1136188.

    • Search Google Scholar
    • Export Citation
  • Le Quéré, C., and Coauthors, 2009: Trends in the sources and sinks of carbon dioxide. Nat. Geosci., 2, 831836, doi:10.1038/ngeo689.

    • Search Google Scholar
    • Export Citation
  • Lovenduski, N. S., and T. Ito, 2009: The future evolution of the Southern Ocean CO2 sink. J. Mar. Res., 67, 597617, doi:10.1357/002224009791218832.

    • Search Google Scholar
    • Export Citation
  • Lovenduski, N. S., N. Gruber, and S. C. Doney, 2008: Toward a mechanistic understanding of the decadal trends in the Southern Ocean carbon sink. Global Biogeochem. Cycles, 22, GB3016, doi:10.1029/2007GB003139.

    • Search Google Scholar
    • Export Citation
  • Madec, G., 2008: NEMO ocean engine. IPSL Note du Pole de Modélisation 27, 321 pp.

  • Marinov, I., and A. Gnanadesikan, 2011: Changes in ocean circulation and carbon storage are decoupled from air-sea CO2 fluxes. Biogeosciences, 8, 505513, doi:10.5194/bg-8-505-2011.

    • Search Google Scholar
    • Export Citation
  • Marinov, I., M. Follows, A. Gnanadesikan, J. L. Sarmiento, and R. D. Slater, 2008a: How does ocean biology affect atmospheric pCO2? Theory and models. J. Geophys. Res., 113, C07032, doi:10.1029/2007JC004598.

    • Search Google Scholar
    • Export Citation
  • Marinov, I., A. Gnanadesikan, J. L. Sarmiento, J. R. Toggweiler, M. Follows, and B. K. Mignone, 2008b: Impact of oceanic circulation on biological carbon storage in the ocean and atmospheric pCO2. Global Biogeochem. Cycles, 22, GB3007, doi:10.1029/2007GB002958.

    • Search Google Scholar
    • Export Citation
  • Marti, O., and Coauthors, 2010: Key features of the IPSL ocean atmosphere model and its sensitivity to atmospheric resolution. Climate Dyn., 34, 126, doi:10.1007/s00382-009-0640-6.

    • Search Google Scholar
    • Export Citation
  • Mikalhof-Fletcher, S. E., and Coauthors, 2007: Inverse estimates of the oceanic sources and sinks of natural CO2 and the implied oceanic carbon transport. Global Biogeochem. Cycles, 21, GB1010, doi:10.1029/2006GB002751.

    • Search Google Scholar
    • Export Citation
  • Murnane, R., J. L. Sarmiento, and C. Le Quéré, 1999: Spatial distribution of air-sea CO2 fluxes and the interhemispheric transport of carbon by the oceans. Global Biogeochem. Cycles, 13, 287305.

    • Search Google Scholar
    • Export Citation
  • Orsi, A. H., G. C. Johnson, and J. L. Bullister, 1999: Circulation, mixing, and production of Antarctic Bottom Water. Prog. Oceanogr., 43, 55109, doi:10.1016/S0079-6611(99)00004-X.

    • Search Google Scholar
    • Export Citation
  • Roy, T., and Coauthors, 2011: Regional impacts of climate change and atmospheric CO2 on future ocean carbon uptake: A multimodel linear feedback analysis. J. Climate, 24, 23002318.

    • Search Google Scholar
    • Export Citation
  • Sabine, C. L., and Coauthors, 2004: The oceanic sink for anthropogenic CO2. Science, 305, 367371, doi:10.1126/science.1097403.

  • Sallée, J.-B., K. Speer, S. Rintoul, and S. Wijffels, 2011: Southern Ocean thermocline ventilation. J. Phys. Oceanogr., 40, 509529.

  • Sarmiento, J. L., and N. Gruber, 2006: Ocean Biogeochemical Dynamics. Princeton University Press, 503 pp.

  • Sarmiento, J. L., P. Monfray, E. Maier-Reimer, O. Aumont, R. J. Murnane, and J. C. Orr, 2000: Sea-air CO2 fluxes and carbon transport: A comparison of three ocean general circulation models. Global Biogeochem. Cycles, 14, 12671281.

    • Search Google Scholar
    • Export Citation
  • Sarmiento, J. L., N. Gruber, M. A. Brzezinski, and J. P. Dunne, 2004: High-latitude controls of thermocline nutrients and low latitude biological productivity. Nature, 479, 556, doi:10.1038/nature10605.

    • Search Google Scholar
    • Export Citation
  • Sloyan, B., and S. Rintoul, 2001: The Southern Ocean limb of the global deep overturning circulation. J. Phys. Oceanogr., 31, 143173.

    • Search Google Scholar
    • Export Citation
  • Sørensen, J., J. Ribbe, and G. Shaffer, 2001: Antarctic Intermediate Water mass formation in ocean general circulation models. J. Phys. Oceanogr., 31, 32953311.

    • Search Google Scholar
    • Export Citation
  • Taylor, K. E., R. J. Stouffer, and G. A. Meehl, 2012: An overview of CMIP5 and the experiment design. Bull. Amer. Meteor. Soc., 93, 485–498.

    • Search Google Scholar
    • Export Citation
  • Tjiputra, J. F., K. Assmann, M. Bentsen, I. Bethke, O. H. Otterå, C. Sturm, and C. Heinze, 2010: Bergen earth system model (BCM-C): Model description and regional climate-carbon cycle feedbacks assessment. Geosci. Model Dev., 3, 123141, doi:10.5194/gmd-3-123-2010.

    • Search Google Scholar
    • Export Citation
  • Toggweiler, J. R., J. L. Russell, and S. R. Carson, 2006: Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages. Paleoceanography, 21, PA2005, doi:10.1029/2005PA001154.

    • Search Google Scholar
    • Export Citation
  • Tomczak, M., and S. Liefrink, 2005: Interannual variations of water mass volumes in the Southern Ocean. J. Atmos. Ocean Sci., 10, 3142.

    • Search Google Scholar
    • Export Citation
  • Treguier, A. M., I. M. Held, and V. D. Larichev, 1997: Parameterization of quasigeostrophic eddies in primitive equation ocean models. J. Phys. Oceanogr., 27, 567580.

    • Search Google Scholar
    • Export Citation
  • Tschumi, T., F. Joos, and P. Parekh, 2008: How important are Southern Hemisphere wind changes for low glacial carbon dioxide? A model study. Paleoceanography, 23, PA4208, doi:10.1029/2008PA001592.

    • Search Google Scholar
    • Export Citation
  • Verdy, A., S. Dutkiewicz, M. J. Follows, J. Marshall, and A. Czaja, 2007: Carbon dioxide and oxygen fluxes in the Southern Ocean: Mechanisms of interannual variability. Global Biogeochem. Cycles, 21, GB2020, doi:10.1029/2006GB002916.

    • Search Google Scholar
    • Export Citation
  • Yoshikawa, C., M. Kawamiya, T. Kato, Y. Yamanaka, and T. Matsuno, 2008: Geographical distribution of the feedback between future climate change and the carbon cycle. J. Geophys. Res., 113, G03002, doi:10.1029/2007JG000570.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 371 182 8
PDF Downloads 254 109 2

Water Mass Analysis of Effect of Climate Change on Air–Sea CO2 Fluxes: The Southern Ocean

View More View Less
  • 1 LSCE/IPSL, Paris, France, and CNRM–GAME, Météo-France, CNRS, Toulouse, France
  • | 2 Stazione Zoologica Anton Dohrn, Naples, Italy
  • | 3 LSCE/IPSL, Paris, France
  • | 4 IPSL/LOCEAN, Paris, France, and NOC, Southampton, United Kingdom
Restricted access

Abstract

Impacts of climate change on air–sea CO2 exchange are strongly region dependent, particularly in the Southern Ocean. Yet, in the Southern Ocean the role of water masses in the uptake of anthropogenic carbon is still debated. Here, a methodology is applied that tracks the carbon flux of each Southern Ocean water mass in response to climate change. A global marine biogeochemical model was coupled to a climate model, making 140-yr Coupled Model Intercomparison Project phase 5 (CMIP5)-type simulations, where atmospheric CO2 increased by 1% yr−1 to 4 times the preindustrial concentration (4 × CO2). Impacts of atmospheric CO2 (carbon-induced sensitivity) and climate change (climate-induced sensitivity) on the water mass carbon fluxes have been isolated performing two sensitivity simulations. In the first simulation, the atmospheric CO2 influences solely the marine carbon cycle, while in the second simulation, it influences both the marine carbon cycle and earth’s climate. At 4 × CO2, the cumulative carbon uptake by the Southern Ocean reaches 278 PgC, 53% of which is taken up by modal and intermediate water masses. The carbon-induced and climate-induced sensitivities vary significantly between the water masses. The carbon-induced sensitivities enhance the carbon uptake of the water masses, particularly for the denser classes. But, enhancement strongly depends on the water mass structure. The climate-induced sensitivities either strengthen or weaken the carbon uptake and are influenced by local processes through changes in CO2 solubility and stratification, and by large-scale changes in outcrop surface (OS) areas. Changes in OS areas account for 45% of the climate-induced reduction in the Southern Ocean carbon uptake and are a key factor in understanding the future carbon uptake of the Southern Ocean.

Corresponding author address: Roland Séférian, Laboratoire des Sciences du Climat et de L’Environnement, Bâtiment 712, F-91191 Gif sur Yvette CEDEX, France. E-mail: roland.seferian@lsce.ipsl.fr

Abstract

Impacts of climate change on air–sea CO2 exchange are strongly region dependent, particularly in the Southern Ocean. Yet, in the Southern Ocean the role of water masses in the uptake of anthropogenic carbon is still debated. Here, a methodology is applied that tracks the carbon flux of each Southern Ocean water mass in response to climate change. A global marine biogeochemical model was coupled to a climate model, making 140-yr Coupled Model Intercomparison Project phase 5 (CMIP5)-type simulations, where atmospheric CO2 increased by 1% yr−1 to 4 times the preindustrial concentration (4 × CO2). Impacts of atmospheric CO2 (carbon-induced sensitivity) and climate change (climate-induced sensitivity) on the water mass carbon fluxes have been isolated performing two sensitivity simulations. In the first simulation, the atmospheric CO2 influences solely the marine carbon cycle, while in the second simulation, it influences both the marine carbon cycle and earth’s climate. At 4 × CO2, the cumulative carbon uptake by the Southern Ocean reaches 278 PgC, 53% of which is taken up by modal and intermediate water masses. The carbon-induced and climate-induced sensitivities vary significantly between the water masses. The carbon-induced sensitivities enhance the carbon uptake of the water masses, particularly for the denser classes. But, enhancement strongly depends on the water mass structure. The climate-induced sensitivities either strengthen or weaken the carbon uptake and are influenced by local processes through changes in CO2 solubility and stratification, and by large-scale changes in outcrop surface (OS) areas. Changes in OS areas account for 45% of the climate-induced reduction in the Southern Ocean carbon uptake and are a key factor in understanding the future carbon uptake of the Southern Ocean.

Corresponding author address: Roland Séférian, Laboratoire des Sciences du Climat et de L’Environnement, Bâtiment 712, F-91191 Gif sur Yvette CEDEX, France. E-mail: roland.seferian@lsce.ipsl.fr
Save