The Stability of the Thermohaline Circulation in Global Warming Experiments

Andreas Schmittner Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland

Search for other papers by Andreas Schmittner in
Current site
Google Scholar
PubMed
Close
and
Thomas F. Stocker Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland

Search for other papers by Thomas F. Stocker in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

A simplified climate model of the coupled ocean–atmosphere system is used to perform extensive sensitivity studies concerning possible future climate change induced by anthropogenic greenhouse gas emissions. Supplemented with an active atmospheric hydrological cycle, experiments with different rates of CO2 increase and different climate sensitivities are performed. The model exhibits a threshold value of atmospheric CO2 concentration beyond which the North Atlantic Deep Water formation stops and never recovers. For a climate sensitivity that leads to an equilibrium warming of 3.6°C for a doubling of CO2 and a rate of CO2 increase of 1% yr−1, the threshold lies between 650 and 700 ppmv.

Moreover, it is shown that the stability of the thermohaline circulation depends on the rate of increase of greenhouse gases. For a slower increase of atmospheric pCO2 the final amount that can be reached without a shutdown of the circulation is considerably higher. This rate-sensitive response is due to the uptake of heat and excess freshwater from the uppermost layers to the deep ocean.

The increased equator-to-pole freshwater transport in a warmer atmosphere is mainly responsible for the cessation of deep water formation in the North Atlantic. Another consequence of the enhanced latent heat transport is a stronger warming at high latitudes. A model version with fixed water vapor transport exhibits uniform warming at all latitudes. The inclusion of a simple parameterization of the ice-albedo feedback increases the model sensitivity and further decreases the pole-to-equator temperature difference in a greenhouse climate. The possible range of CO2 threshold concentrations and its dependency on the rate of CO2 increase, on the climate sensitivity, and on other model parameters are discussed.

Corresponding author address: Andreas Schmittner, Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.

Email: schmittner@climate.unibe.ch

Abstract

A simplified climate model of the coupled ocean–atmosphere system is used to perform extensive sensitivity studies concerning possible future climate change induced by anthropogenic greenhouse gas emissions. Supplemented with an active atmospheric hydrological cycle, experiments with different rates of CO2 increase and different climate sensitivities are performed. The model exhibits a threshold value of atmospheric CO2 concentration beyond which the North Atlantic Deep Water formation stops and never recovers. For a climate sensitivity that leads to an equilibrium warming of 3.6°C for a doubling of CO2 and a rate of CO2 increase of 1% yr−1, the threshold lies between 650 and 700 ppmv.

Moreover, it is shown that the stability of the thermohaline circulation depends on the rate of increase of greenhouse gases. For a slower increase of atmospheric pCO2 the final amount that can be reached without a shutdown of the circulation is considerably higher. This rate-sensitive response is due to the uptake of heat and excess freshwater from the uppermost layers to the deep ocean.

The increased equator-to-pole freshwater transport in a warmer atmosphere is mainly responsible for the cessation of deep water formation in the North Atlantic. Another consequence of the enhanced latent heat transport is a stronger warming at high latitudes. A model version with fixed water vapor transport exhibits uniform warming at all latitudes. The inclusion of a simple parameterization of the ice-albedo feedback increases the model sensitivity and further decreases the pole-to-equator temperature difference in a greenhouse climate. The possible range of CO2 threshold concentrations and its dependency on the rate of CO2 increase, on the climate sensitivity, and on other model parameters are discussed.

Corresponding author address: Andreas Schmittner, Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.

Email: schmittner@climate.unibe.ch

Save
  • Arrhenius, S., 1896: On the influence of carbonic acid in the air upon the temperature of the ground. Philos. Mag.,41, 237–276.

  • Broecker, W. S., and G. H. Denton, 1989: The role of ocean–atmosphere reorganizations in glacial cycles. Geochim. Cosmochim. Acta,53, 2465–2501.

  • ——, D. Peteet, and D. Rind, 1985: Does the ocean–atmosphere system have more than one stable mode of operation? Nature,315, 21–25.

  • Bryan, F., 1986: High-latitude salinity effects and interhemispheric thermohaline circulations. Nature,323, 301–304.

  • Chen, D., R. Gerdes, and G. Lohmann, 1995: A 1-D atmospheric energy balance model developed for ocean modelling. Theor. Appl. Climatol.,51, 25–38.

  • Crowley, T. J., 1992: North Atlantic deep water cools the Southern Hemisphere. Paleoceanography,7 (4), 489–497.

  • ——, and G. R. North, 1991: Paleoclimatology. Oxford Monogr. on Geol. and Geophys., No. 18, Oxford University Press, 16 pp.

  • Cubasch, U., K. Hasselmann, H. Hoeck, E. Maier-Reimer, U. Mikolajewicz, B. D. Santer, and R. Sausen, 1992: Time-dependent greenhouse warming computations with a coupled ocean–atmosphere model. Climate Dyn.,8, 55–69.

  • ——, B. D. Santer, A. Hellbach, G. Hegerl, H. Hoeck, E. Maier-Reimer, U. Mikolajewicz, A. Stössel, and R. Voss, 1994: Monte Carlo climate change forecasts with a global coupled ocean–atmosphere model. Climate Dyn.,10, 1–19.

  • ——, G. C. Hegerl, A. Hellbach, H. Hoeck, U. Mikolajewicz, B. D. Santer, and R. Voss, 1995: A climate change simulation starting 1935. Climate Dyn.,11, 71–84.

  • Egger, J., 1995: Flux correction: Tests with a simple ocean–atmosphere model. Climate Dyn.,13, 285–292.

  • Fanning, A. F., and A. J. Weaver, 1996: An atmospheric energy–moisture balance model: Climatology, interpentadal climate change, and coupling to an oceanic general circulation model. J. Geophys. Res.,101, 15 111–15 128.

  • ——, and ——, 1997: Temporal-geographical meltwater influences on the North Atlantic conveyor: Implications for the Younger Dryas. Paleoceanography,12, 307–320.

  • Fourier, J.-B. J., 1824: Remarques générales sur les températures du globe terrestre et des espaces planétaires. Ann. Chim. Phys.,27, 136–167.

  • Ghil, M., 1976: Climate stability for a Sellers-type model. J. Atmos. Sci.,33, 3–20.

  • ——, 1985: Theoretical climate dynamics: An introduction. Turbulence and Predictability in Geophysical Fluid Dynamics and Climate Dynamics, M. Ghil, Ed., North-Holland, 347–402.

  • Gill, A. E., 1982: Atmosphere–Ocean Dynamics. International Geophysics Series, Vol. 30, Academic Press, 662 pp.

  • Gregory, J. M., and J. F. B. Mitchell, 1997: The climate response to CO2 of the Hadley Centre coupled AOGCM with and without flux adjustment. Geophys. Res. Lett.,24, 1943–1946.

  • Harvey, L. D. D., 1988: A semianalytic energy balance climate model with explicit sea ice and snow physics. J. Climate,1, 1065–1084.

  • Houghton, J. T., L. G. Meira Filho, B. A. Callander, N. Harris, A. Kattenberg, and K. Maskell, Eds., 1996: Climate Change 1995:The Science of Climate Change. Cambridge University Press, 285 pp.

  • James, I. N., 1994: Introduction to Circulating Atmospheres. Cambridge University Press, 246 pp.

  • Keeling, C. D., and T. P. Whorf, 1994: Atmospheric CO2 records from sites in the SIO network. Trends93: A Compendium of Data on Global Change, T. Boden, D. Kaiser, R. Sepanski, and F. Stoss, Eds., Carbon Dioxide Information Analysis Center, 16–26.

  • Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Paper 13, U.S. Government Printing Office, Washington, DC, 173 pp.

  • ——, and T. P. Boyer, 1994: NOAA Atlas NESDIS 4, World Ocean Atlas 1994. Vol. 4, Temperature, U.S. Department of Commerce, 117 pp.

  • ——, R. Burgett, and T. P. Boyer, 1994: NOAA Atlas NESDIS 3, World Ocean Atlas 1994. Vol. 3, Salinity, U.S. Department of Commerce, 99 pp.

  • Lorenz, E. N., 1979: Forced and free variations of weather and climate. J. Atmos. Sci.,36, 1367–1376.

  • Manabe, S., and R. J. Stouffer, 1988: Two stable equilibria of a coupled ocean–atmosphere model. J. Climate,1, 841–866.

  • ——, and ——, 1993: Century-scale effects of increased atmospheric CO2 on the ocean–atmosphere system. Nature,364, 215–218.

  • ——, and ——, 1994: Multiple-century response of a coupled ocean–atmosphere model to an increase of atmospheric carbon dioxide. J. Climate,7, 5–23.

  • ——, ——, M. J. Spelman, and K. Bryan, 1991: Transient responses of a coupled ocean–atmosphere model to gradual changes of atmospheric CO2. J. Climate,4, 785–818.

  • Marchal, O., T. F. Stocker, and F. Joos, 1998: A latitude-depth, circulation-biogeochemical ocean model for paleoclimate studies: Development and sensitivities. Tellus,50B, 290–316.

  • Neftel, A., H. Oeschger, T. Staffelbach, and B. Stauffer, 1988: CO2 record in the Byrd ice core 50,000–5,000 years BP. Nature,331, 609–611.

  • Oeschger, H., J. Beer, U. Siegenthaler, B. Stauffer, W. Dansgaard, and C. C. Langway, 1984: Late glacial climate history from ice cores. Climate Processes and Climate Sensitivity, Geophys. Monogr., No. 29, Amer. Geophys. Union, 299–306.

  • Oort, A. H., 1983: Global atmosphere circulation statistics, 1958–1973. NOAA Prof. Paper 14, U.S. Government Printing Office, Washington, DC, 180 pp.

  • Peixoto, J. P., and A. H. Oort, 1992: Physics of Climate. American Institute of Physics, 195 pp.

  • Rahmstorf, S., J. Marotzke, and J. Willebrand, 1996: Stability of the thermohaline circulation. The Warmwatersphere of the North Atlantic Ocean, W. Krauss, Ed., Gebrüder Borntraeger, 129–158.

  • Revelle, R., 1985: The scientific history of carbon dioxide. The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present, Geophys. Monogr., No. 32, Amer. Geophys. Union, 1–4.

  • Sausen, R., K. Barthel, and K. Hasselmann, 1988: Coupled ocean–atmosphere models with flux correction. Climate Dyn.,2, 145–163.

  • Sellers, W. D., 1969: A global climate model based on the energy balance of the earth–atmosphere system. J. Appl. Meteor.,8, 392–400.

  • Shine, K. P., R. G. Derwent, D. J. Wuebbles, and J.-J. Morcrette, 1995: Radiative forcing of climate. Climate Change: The IPCC Scientific Assessment, J. Y. Houghton, G. J. Jenkins, and J. J. Ephraums, Eds., Cambridge University Press, 41–68.

  • Stephens, G. L., G. G. Campbell, and T. H. von der Haar, 1981: Earth radiation budgets. J. Geophys. Res.,86, 9739–9760.

  • Stocker, T. F., and D. G. Wright, 1996: Rapid changes in ocean circulation and atmospheric radiocarbon. Paleoceanography,11, 773–796.

  • ——, and A. Schmittner, 1997: Influence of CO2 emission rates on the stability of the thermohaline circulation. Nature,388, 862–865.

  • ——, D. G. Wright, and L. A. Mysak, 1992: A zonally averaged, coupled ocean–atmosphere model for paleoclimate studies. J. Climate,5, 773–797.

  • Syktus, J., J. Chappel, R. Oglesby, J. Larson, S. Marshall, and B. Saltzman, 1997: Latitudinal dependence of signal-to-noise patterns from two general circulation models with CO2 forcing. Climate Dyn.,13, 293–302.

  • Wright, D. G., and T. F. Stocker, 1991: A zonally averaged ocean model for the thermohaline circulation. Part I: Model development and flow dynamics. J. Phys. Oceanogr.,21, 1713–1724.

  • ——, and ——, 1993: Younger Dryas experiments. Ice in the Climate System, W. R. Peltier, Ed., NATO ASI Series, Vol. 12, Springer-Verlag, 395–416.

  • ——, ——, and D. Mercer, 1998: Closures used in zonally averaged ocean models. J. Phys. Oceanogr.,28, 791–804.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 875 309 11
PDF Downloads 547 181 7