• Cubasch, U., and Coauthors, 2001: Projections of future climate change. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, J. T. Houghton et al., Eds., Cambridge University Press, 526–582.

    • Search Google Scholar
    • Export Citation
  • Dixon, K. W., , J. L. Bullister, , R. H. Gammon, , and R. J. Stouffer, 1996: Examining a coupled climate model using CFC-11 as an ocean tracer. Geophys. Res. Lett., 23 , 19571960.

    • Search Google Scholar
    • Export Citation
  • Dixon, K. W., , T. L. Delworth, , M. J. Spelman, , and R. J. Stouffer, 1999: The influence of transient surface fluxes on North Atlantic overturning in a coupled GCM climate change experiment. Geophys. Res. Lett., 26 , 27492752.

    • Search Google Scholar
    • Export Citation
  • England, M. H., 1995: Using chlorofluorocarbons to assess ocean climate models. Geophys. Res. Lett., 22 , 30513054.

  • England, M. H., , and S. Rahmstorf, 1999: Sensitivity of ventilation rates and radiocarbon uptake to subsurface mixing parameterization in ocean models. J. Phys. Oceanogr., 29 , 28022827.

    • Search Google Scholar
    • Export Citation
  • Ganopolski, A., , S. Rahmstorf, , V. Petoukov, , and M. Claussen, 1998: Simulation of modern and glacial climate with a coupled model of intermediate complexity. Nature, 391 , 351356.

    • Search Google Scholar
    • Export Citation
  • Gordon, C. T., , and W. F. Stern, 1982: A description of the GFDL spectral model. Mon. Wea. Rev., 110 , 625644.

  • Manabe, S., 1969: Climate and the ocean circulation. I. The atmospheric circulation and the hydrology of the earth's surface. Mon. Wea. Rev., 97 , 739774.

    • Search Google Scholar
    • Export Citation
  • Manabe, S., , R. J. Stouffer, , M. J. Spelman, , and K. Bryan, 1991: Transient responses of a coupled ocean–atmosphere model to gradual changes of atmospheric CO2. Part I. Annual mean response. J. Climate, 4 , 785817.

    • Search Google Scholar
    • Export Citation
  • Ostlund, H. G., , H. Graig, , W. S. Broecker, , and D. Spencer, 1987: Shore Based Data and Graphics. Vol. 7, GEOSECS Atlantic, Pacific and Indian Ocean Expeditions, National Science Foundation, 230 pp.

    • Search Google Scholar
    • Export Citation
  • Redi, M. H., 1982: Oceanic isopycnal mixing by coordinate rotation. J. Phys. Oceanogr., 12 , 11541158.

  • Robitaille, D. Y., , and A. J. Weaver, 1995: Validation of sub-grid-scale mixing schemes using CFCs in a global ocean model. Geophys. Res. Lett., 22 , 28172920.

    • Search Google Scholar
    • Export Citation
  • Spelman, M. J., , and S. Manabe, 1984: Influence of oceanic heat transport upon the sensitivity of a model climate. J. Geophys. Res., 89 , 571586.

    • Search Google Scholar
    • Export Citation
  • Stouffer, R. J., , and S. Manabe, 1999: Response of a coupled ocean–atmosphere model to increasing atmospheric carbon dioxide: Sensitivity to the rate of increase. J. Climate, 12 , 22242237.

    • Search Google Scholar
    • Export Citation
  • Stouffer, R. J., , and S. Manabe, 2003: Equilibrium response of thermohaline circulation to large changes in atmospheric CO2 concentration. Climate Dyn., 20 , 759773.

    • Search Google Scholar
    • Export Citation
  • Toggweiler, J. R., , and B. Samuels, 1993: New radiocarbon constraints on the upwelling of abyssal water to the ocean's surface. Global Carbon Cycle, Springer-Verlag, 333–366.

    • Search Google Scholar
    • Export Citation
  • Toggweiler, J. R., , K. Dixon, , and K. Bryan, 1989: Simulations of radiocarbon in a course-resolution world ocean model, Part 1: Steady state prebomb distributions. J. Geophys. Res., 94 , 82178242.

    • Search Google Scholar
    • Export Citation
  • Tziperman, E., , and K. Bryan, 1993: Estimating global air–sea fluxes from surface properties and from climatological flux data using an ocean general circulation model. J. Geophys. Res., 98 , 2262922644.

    • Search Google Scholar
    • Export Citation
  • Weaver, A. J., , A. F. Fanning, , M. Ebby, , and E. C. Wiebe, 1998: The climate of the last glacial maximum in a coupled ocean GCM/energy-moisture balance atmosphere model. Nature, 394 , 847853.

    • Search Google Scholar
    • Export Citation
  • Weaver, A. J., , P. B. Duffy, , M. Ebby, , and E. C. Wiebe, 2000: Evaluation of ocean and climate models using present-day observations and forcing. Atmos.–Ocean, 38 , 271301.

    • Search Google Scholar
    • Export Citation
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Time Scales of Climate Response

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  • 1 NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey
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Abstract

A coupled atmosphere–ocean general circulation model (AOGCM) is integrated to a near-equilibrium state with the normal, half-normal, and twice-normal amounts of carbon dioxide in the atmosphere. Most of the ocean below the surface layers achieves 70% of the total response almost twice as fast when the changes in radiative forcing are cooling as compared to the case when they are warming the climate system. In the cooling case, the time to achieve 70% of the equilibrium response in the midoceanic depths is about 500–1000 yr. In the warming case, this response time is 1300–1700 yr. In the Pacific Ocean and the bottom half of the Atlantic Ocean basins, the response is similar to the global response in that the cooling case results in a shorter response time scale. In the upper half of the Atlantic basin, the cooling response time scales are somewhat longer than in the warming case due to changes in the oceanic thermohaline circulation. In the oceanic surface mixed layer and atmosphere, the response time scale is closely coupled. In the Southern Hemisphere, the near-surface response time is slightly faster in the cooling case. However in the Northern Hemisphere, the near-surface response times are faster in the warming case by more than 500 yr at times during the integrations. In the Northern Hemisphere, both the cooling and warming cases have much shorter response time scales than found in the Southern Hemisphere. Oceanic mixing of heat is the key in determining these time scales. It is shown that the model's simulation of present-day radiocarbon and chlorofluorocarbon (CFC) distributions compares favorably to the observations indicating that the quantitative time scales may be realistic.

Corresponding author address: R. J. Stouffer, NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08542. Email: Ronald.Stouffer@noaa.gov

Abstract

A coupled atmosphere–ocean general circulation model (AOGCM) is integrated to a near-equilibrium state with the normal, half-normal, and twice-normal amounts of carbon dioxide in the atmosphere. Most of the ocean below the surface layers achieves 70% of the total response almost twice as fast when the changes in radiative forcing are cooling as compared to the case when they are warming the climate system. In the cooling case, the time to achieve 70% of the equilibrium response in the midoceanic depths is about 500–1000 yr. In the warming case, this response time is 1300–1700 yr. In the Pacific Ocean and the bottom half of the Atlantic Ocean basins, the response is similar to the global response in that the cooling case results in a shorter response time scale. In the upper half of the Atlantic basin, the cooling response time scales are somewhat longer than in the warming case due to changes in the oceanic thermohaline circulation. In the oceanic surface mixed layer and atmosphere, the response time scale is closely coupled. In the Southern Hemisphere, the near-surface response time is slightly faster in the cooling case. However in the Northern Hemisphere, the near-surface response times are faster in the warming case by more than 500 yr at times during the integrations. In the Northern Hemisphere, both the cooling and warming cases have much shorter response time scales than found in the Southern Hemisphere. Oceanic mixing of heat is the key in determining these time scales. It is shown that the model's simulation of present-day radiocarbon and chlorofluorocarbon (CFC) distributions compares favorably to the observations indicating that the quantitative time scales may be realistic.

Corresponding author address: R. J. Stouffer, NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08542. Email: Ronald.Stouffer@noaa.gov

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