Advertisement

Hydrological Cycle Scenarios, Deep Ocean Circulation, and Century/Millennium Climate Change: A Simulation Study Using an Ocean-Atmosphere-Ice Sheet Model

  • Huaxiao Wang
  • G. Edward Birchfield
  • Jonathan J. Rich
Part of the NATO ASI Series book series (volume 12)

Abstract

Rapid climate changes (Dansgaard-Oeschger events) during most of the last glaciation and during the last deglaciation, seen in the Greenland ice cores and a deep sea sediment core in the North Atlantic, are likely caused by dynamical instability of the climate system itself. Here we present, with a simple coupled ocean-atmosphere-ice sheet energy-salt balance model (ESBM), oscillatory feedback mechanisms to explain these climate changes. The major physical mechanisms active in the model are latitudinal heat and salt transports by the thermohaline circulation in the North Atlantic, surface ocean freshwater fluxes associated with melting and growing continental ice sheets in the Northern Hemisphere and with Atlantic to Pacific water vapor transport. The primary positive feedback is between the production of North Atlantic Deep Water (NADW) and the meridional salinity flux to the high latitude North Atlantic Ocean. The principal negative feedback is between the freshwater flux either to or from the continental ice sheets and meridional heat flux to the high-latitude North Atlantic accomplished by the thermohaline circulation.

Water vapor for growing ice sheets is assumed to be transported from the subtropical ocean to the ice sheets around the periphery of the North Atlantic by a ‘baroclinic mass flux’ process-a parameterization of the mechanism of feeding water vapor to continental ice sheets by intense cyclone eddies seen in GCM simulations of the last glacial maximum (Manabe and Broccoli, 1985). Meltwater from the ice sheets is returned to the subtropical Atlantic or to the high-latitude North Atlantic.

Model oscillations are characterized by periods on the order of a few hundred to a thousand years, alternating rates of, NADW production, heat flux from ocean to atmosphere in the high-latitude North Atlantic (and hence the air temperature), and the strength of the global thermohaline circulation as measured by deep outflow from the Atlantic basin to the Southern Ocean. Robust over a wide range of model parameters, the oscillations tend to substantiate the conceptual salt oscillator model proposed by Broecker et al. (1990a) and Birchfield and Broecker (1990).

Inter-basin transport of water vapor in the simulations acts, through the salinity balance for the Atlantic and the basic feedback mechanisms, as a major control process, not only on the climate oscillatory state but on the longer time scale waxing and waning of the continental ice sheets themselves. For a net water vapor flux from the Atlantic to Pacific Ocean, the oscillatory feedback mechanism results in a ‘deglaciation’ scenario in which the entire volume of Northern Hemisphere ice sheets can potentially be dissipated within a few oscillations. If the flux is from the Pacific to Atlantic Ocean, a ’glaciation’ scenario ensues in which large increases in mean ice volume can occur.

Keywords

Southern Ocean Latent Heat Flux Vapor Flux Thermohaline Circulation Freshwater Flux 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Birchfield, G.E. (1989). A coupled ocean-atmosphere climate model: temperature versus salinity effects on the thermohaline circulation, Climate Dynamics, 4, 57–71.CrossRefGoogle Scholar
  2. Birchfield, G.E. and W.S. Broecker (1990) A salt oscillator in the glacial Atlantic? 2. A “scale analysis” model, Paleoceanography, 5, 835–843.CrossRefGoogle Scholar
  3. Birchfield, G.E. and M. Ghil (1993) Climate evolution in the Pliocene-Pleistocene as seen in deep sea 81 80 records and in simulations: internal variability versus orbital forcing, J. Geophys. Res., (in press).Google Scholar
  4. Birchfield, G.E., H. Wang, and J. Rich (1993) Century/millennium internal climate variability: an ocean-atmosphere-continental ice sheet model study, submitted to J. Geophys. Res.Google Scholar
  5. Birchfield, G.E., H. Wang, M. Wyant (1990) A bimodal climate response controlled by water vapor transport in a coupled ocean-atmosphere box model, Paleoceanography, 5, 383–395.CrossRefGoogle Scholar
  6. Boyle, E.A., and L. Keigwin (1987) North Atlantic thermohaline circulation during the past 20,000 years linked to high-latitude surface temperature, Nature, 330, 35–40.CrossRefGoogle Scholar
  7. Broecker, W.S. (1992) The great ocean conveyor, Oceanography, 4, 79–89.Google Scholar
  8. Broecker, W.S., G. Bond, M. Klas, G. Bonani and W. Wolfli (1990a) A salt oscillator in the glacial Atlantic? 1, The concept, Paleoceanography, 5, 469–478.CrossRefGoogle Scholar
  9. Broecker, W.S., T-H Peng, J. Jouzel and G. Russell (1990b) The magnitude of global fresh-water transports of importance to ocean circulation, Clim. Dyn., 4, 73–79.CrossRefGoogle Scholar
  10. Broecker, W.S. (1989) The salinity contrast between the Atlantic and Pacific Oceans during glacial time, Paleoceanography, 4, 207–212.CrossRefGoogle Scholar
  11. Bryan, F. (1986) High-latitude salinity effects and interhemispheric thermohaline circulations, Nature, 323, 301–304.CrossRefGoogle Scholar
  12. Charles, C. and R. Fairbanks (1992) Evidence from Southern Ocean sediments for the effect of North Atlantic deep-water flux on climate, Nature, 355, 416–419.CrossRefGoogle Scholar
  13. Dansgaard W, Clausen HB, Gundestrup N, Hammer CU, Johnsen SJ, Kristinsdottir P, Reeh N (1982) A new Greenland deep ice core, Science, 218, 1273–1277.CrossRefGoogle Scholar
  14. Dansgaard W, S.J. Johnsen, H.B. Clausen, C.C. Langway (1971) Climatic record revealed by the Camp Century ice core, in: Turekian KK (ed) Late Cenozoic Glacial Ages. Hartford Connecticut, Yale Univ. Press, 606 pp.Google Scholar
  15. Duplessy, J.C., L. Labeyrie, M. Arnold, M. Paterne, J. Duprat and T.C.E. van Weering (1992) Changes in surface salinity of the North Atlantic Ocean during the last deglaciation, Nature, 358, 485–488.CrossRefGoogle Scholar
  16. Duplessy JC, Shackleton NJ, Fairbanks RG, Labeyrie L, Oppo D, Kallel N (1988) Deepwater source variations during the last climatic cycle and their impact on the global deepwater circulation, Paleoceanography, 3, 343–360.CrossRefGoogle Scholar
  17. Fairbanks, R.G. (1989) A 17,000-year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation, Nature, 342, 637–642.CrossRefGoogle Scholar
  18. Hammer CU, Clausen HB, Dansgaard W, Neftel A, Kristinsdottir P, Johnson E (1985) Continuous impurity analysis along the Dye 3 deep core. In Langway CC, Oeschger H, Dansgaard W (eds) Geophysics, Geochemistry and the Environment. Amer Geophys Union Mon 33: 90–94.Google Scholar
  19. Keigwin, L.D., Jones, G.A., Lehman, S.J., & Boyle, E.A. (1991) Deglacial meltwater discharge, north Atlantic deep circulation, and abrupt climate change, J. Geophys. Res., 96, 16,811–16, 826.Google Scholar
  20. Lehman, S. and L. Keigwin (1992) Sudden changes in North Atlantic circulation during the last deglaciation, Nature, 356, 757–762.CrossRefGoogle Scholar
  21. LeTreut, H. and Ghil, M. (1983) Orbital forcing, climatic interactions, and glaciation cycles, J. Geophys. Rev., 88, 5167–5190.CrossRefGoogle Scholar
  22. Manabe, S. and A.J. Broccoli (1985) The influence of continental ice sheets on the climate of an ice age, J. Geophys. Res., 90, 2167–2190.CrossRefGoogle Scholar
  23. Manabe, S., R.J. Stouffer (1988) Two stable equilibria of a coupled ocean-atmosphere model, J. Climate, 1, 841–866.CrossRefGoogle Scholar
  24. Marotzke, J., and J. Willebrand (1991) Multiple equilibria of the global thermohaline circulation, J. Phys. Oceanogr., 21, 1372–1385.CrossRefGoogle Scholar
  25. Miller, J.R. and G.L. Russell (1990) Oceanic fresh water transport during the last glacial maximum, Paleoceanography, 5, 397–407.CrossRefGoogle Scholar
  26. Oort, A.H. (1983) Global atmospheric circulation statistics, 1958–1973, NOAA Prof Paper No. 14, US Gov. Print. Office, 180 pp.Google Scholar
  27. Peixoto, J.P., & Oort A.H. (1992) Physics of Climate, American Institute of Physics, New York, 520 pp.Google Scholar
  28. Peixoto, J.P., & Oort A.H. (1983) The atmospheric branch of the hydrological cycle and climate, in Variations in the Global Water Budget (eds A. Street-Perrott et al.) 5–65, D. Reidel, Hingham, Mass., 1983.Google Scholar
  29. Rooth, C. (1982) Hydrology and ocean circulation. Progress in Oceanography., 11, 131–149.CrossRefGoogle Scholar
  30. Stocker, T.F., DG Wright and LA Mysak (1992) A zonally averaged, coupled ocean-atmosphere model for paleoclimate studies, J. Climate, 5, 773–797.CrossRefGoogle Scholar
  31. Stommel, H. (1961) Thermohaline convection with two stable regimes of flow. Tellus, 13, 224–228.CrossRefGoogle Scholar
  32. Wang H, and Birchfield G.E. (1992a) An energy-salinity balance climate model: water vapor transport as a cause of changes in the global thermohaline circulation, J. Geophys. Res., 97, 2335–2346.CrossRefGoogle Scholar
  33. Wang H, and Birchfield G.E. (1992b) Atmospheric water vapor flux, bifurcation of the thermohaline circulation, and climate change, Climate Dynamics, 4, 49–53.Google Scholar
  34. Welander, P. (1986) Thermohaline effects in the ocean circulation and related simple models, in Large-scale transport processes in oceans and atmosphere, eds, J. Willebrand, D.L.T.Anderson, D. Reidel (Dordrecht), 379pp., 1986.Google Scholar
  35. Zaucker F, and Broecker WS, The influence of atmospheric moisture transport on the fresh water balance of the Atlantic drainage basin: general circulation model simulations and observations. J Geophys Res, 97: 2765–2773, 1992.Google Scholar
  36. Zaucker, F, Observed versus modelled freshwater fluxes and their impact on the global thermohaline circulation, Ph.D. dissertation, Ruprecht-KarlsUniversitat, Heidelberg, 90 pp, 1992.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1993

Authors and Affiliations

  • Huaxiao Wang
    • 1
  • G. Edward Birchfield
    • 1
  • Jonathan J. Rich
    • 1
  1. 1.Department of Geological SciencesNorthwestern UniversityEvanstonUSA

Personalised recommendations