• Baines, P. G., and C. K. Folland, 2007: Evidence for a rapid global climate shift across the late 1960s. J. Climate, 20 , 27212744.

  • Behl, R. J., and J. P. Kennett, 1996: Brief interstadial events in the Santa Barbara basin, NE Pacific, during the past 60 kyr. Nature, 379 , 243246.

    • Search Google Scholar
    • Export Citation
  • Broecker, W. S., 1987: The biggest chill. Nat. Hist., 96 , 7482.

  • Broecker, W. S., 1998: Paleocean circulation during the last deglaciation: A bipolar seesaw? Paleoceanography, 13 , 119121.

  • Bryden, H. L., H. R. Longworth, and S. A. Cunningham, 2005: Slowing of the Atlantic meridional overturning circulation at 25°N. Nature, 483 , 655657.

    • Search Google Scholar
    • Export Citation
  • Cessi, P., K. Bryan, and R. Zhang, 2004: Global seiching of thermocline waters between the Atlantic and the Indian–Pacific Ocean Basins. Geophys. Res. Lett., 31 , L04302. doi:10.1029/2003GL019091.

    • Search Google Scholar
    • Export Citation
  • Cronin, T. M., G. S. Dwyer, T. S. Kamiya, S. Schwede, and D. A. Willard, 2003: Medieval warm period, Little Ice Age and 20th century temperature variability from Chesapeake Bay. Global Planet. Change, 36 , 1729.

    • Search Google Scholar
    • Export Citation
  • Crowley, T. J., 1992: North Atlantic Deep Water cools the Southern Hemisphere. Paleoceanography, 7 , 489497.

  • Curry, R., and C. Mauritzen, 2005: Dilution of the northern North Atlantic Ocean in recent decades. Science, 308 , 17721774.

  • Curry, R., B. Dickson, and I. Yashayaev, 2003: A change in the freshwater balance of the Atlantic Ocean over the past four decades. Nature, 426 , 826829.

    • Search Google Scholar
    • Export Citation
  • Dansgaard, W., and Coauthors, 1993: Evidence for general instability of past climate from a 250-kyr ice-core record. Nature, 364 , 218220.

    • Search Google Scholar
    • Export Citation
  • Deser, C., and M. L. Blackmon, 1993: Surface climate variations over the North Atlantic Ocean during winter. J. Climate, 6 , 17431753.

    • Search Google Scholar
    • Export Citation
  • Dickson, R. R., J. Meincke, S. A. Malmberg, and A. J. Lee, 1988: The “great salinity anomaly” in the northern Atlantic 1968–1982. Prog. Oceanogr., 20 , 103151.

    • Search Google Scholar
    • Export Citation
  • Dickson, R. R., Y. Yashayaev, J. Meincke, B. Turrell, S. Dye, and J. Holfort, 2002: Rapid freshening of the deep North Atlantic Ocean over the past four decades. Nature, 416 , 832837.

    • Search Google Scholar
    • Export Citation
  • Dima, M., and G. Lohmann, 2007: A hemispheric mechanism for the Atlantic multidecadal oscillation. J. Climate, 20 , 27062719.

  • Ellison, C. R., M. R. Chapman, and I. R. Hall, 2006: Surface–deep ocean interactions during the cold climate event 8200 years ago. Science, 312 , 19291932.

    • Search Google Scholar
    • Export Citation
  • EPICA Community Members, 2006: One-to-one coupling of glacial climate variability in Greenland and Antarctica. Nature, 444 , 195198.

  • Flato, G. M., and G. J. Boer, 2001: Warming asymmetry in climate change simulations. Geophys. Res. Lett., 28 , 195198.

  • Goosse, H., and H. A. Renssen, 2001: Two-phase response of the Southern Ocean to an increase in greenhouse gas concentrations. Geophys. Res. Lett., 28 , 34693472.

    • Search Google Scholar
    • Export Citation
  • Goosse, H., H. Renssen, F. M. Selten, R. J. Haarsma, and J. D. Opsteegh, 2002: Potential causes of abrupt climate events: A numerical study with a three-dimensional climate model. Geophys. Res. Lett., 29 , 1860. doi:10.1029/2002GL014993.

    • Search Google Scholar
    • Export Citation
  • Gregory, J. M., and Coauthors, 2005: A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration. Geophys. Res. Lett., 32 , L12703. doi:10.1029/2005GL023209.

    • Search Google Scholar
    • Export Citation
  • Hansen, B., W. R. Turrell, and S. Osterhus, 2001: Decreasing overflow from the Nordic seas into the Atlantic Ocean through the Faroe Bank channel since 1950. Nature, 411 , 927930.

    • Search Google Scholar
    • Export Citation
  • Haywood, J. M., R. J. Stouffer, R. T. Wetherald, S. Manabe, and V. Ramaswamy, 1997: Transient response of a coupled model to estimated changes in greenhouse gas and sulfate concentrations. Geophys. Res. Lett., 24 , 13351338.

    • Search Google Scholar
    • Export Citation
  • Kiefer, T., M. Sarnthein, H. Erlenkeuser, P. M. Grootes, and A. P. Roberts, 2001: North Pacific response to millennial-scale changes in ocean circulation over the last 60 kyr. Paleoceanography, 16 , 179189.

    • Search Google Scholar
    • Export Citation
  • Kim, J-H., N. Rimbu, S. J. Lorentz, G. Lohmann, S-I. Nam, S. Schouten, C. Ruhlemann, and R. R. Schneider, 2004: Pacific and North Atlantic sea-surface temperature variability during Holocene. Quat. Sci. Rev., 23 , 21412154.

    • Search Google Scholar
    • Export Citation
  • Knight, R. A., R. J. Allan, C. K. Folland, M. Vellinga, and M. E. A. Mann, 2005: A signature of persistent natural thermohaline circulation cycles in observed climate. Geophys. Res. Lett., 32 , L20708. doi:10.1029/2005GL024233.

    • Search Google Scholar
    • Export Citation
  • Latif, M., and Coauthors, 2004: Reconstructing, monitoring, and predicting multidecadal-scale changes in the North Atlantic thermohaline circulation with sea surface temperature. J. Climate, 17 , 16051614.

    • Search Google Scholar
    • Export Citation
  • Latif, M., C. Boning, J. Willebrand, A. Biastoch, J. Dengg, N. Keenlyside, U. Schweckendiek, and G. Madec, 2006: Is the thermohaline circulation changing? J. Climate, 19 , 46314637.

    • Search Google Scholar
    • Export Citation
  • LeGrande, A. N., G. A. Schmidt, D. T. Shindell, C. V. Field, R. L. Miller, D. M. Koch, G. Faluvegi, and G. Hoffmann, 2006: Consistent simulations of multiple proxy responses to an abrupt climate change event. Proc. Natl. Acad. Sci. USA, 103 , 837842.

    • Search Google Scholar
    • Export Citation
  • Lohmann, G., 2003: Atmospheric and oceanic freshwater transport during weak Atlantic overturning circulation. Tellus, 55A , 438449.

  • Lohmann, G., H. Haak, and J. H. Jungclaus, 2008: Estimating trends of Atlantic meridional overturning circulation from long-term hydrografic data and model simulations. Ocean Dyn., 58 , 127138.

    • Search Google Scholar
    • Export Citation
  • Lorentz, E. N., 1956: Empirical orthogonal functions and statistical weather prediction. Statistical Forecasting Project Scientific Rep. 1, Defense Doc. Center 110268, Massachusetts Institute of Technology, 49 pp.

    • Search Google Scholar
    • Export Citation
  • Manabe, S., and R. J. Stouffer, 1997: Coupled ocean–atmosphere model response to freshwater input: Comparison to Younger Dryas event. Paleoceanography, 12 , 321336.

    • Search Google Scholar
    • Export Citation
  • Manabe, S., and R. J. Stouffer, 2007: Role of ocean in global warming. J. Meteor. Soc. Japan, 85 , 385403.

  • Manabe, S., K. Bryan, and M. J. Spelman, 1990: Transient response of a global ocean–atmosphere model to a doubling of atmospheric carbon dioxide. J. Phys. Oceanogr., 20 , 722749.

    • 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 , 785818.

    • Search Google Scholar
    • Export Citation
  • Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace, and R. C. Francis, 1997: A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Amer. Meteor. Soc., 78 , 10691079.

    • Search Google Scholar
    • Export Citation
  • McManus, J. F., R. Francois, J-M. Gherardi, L. D. Kelgwin, and S. Brown-Leger, 2004: Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes. Nature, 428 , 834837.

    • Search Google Scholar
    • Export Citation
  • Preisendorfer, R. H., 1988: Principal Component Analysis in Meteorology and Oceanography. Elsevier, 425 pp.

  • Rahmstorf, S., 2002: Ocean circulation and climate during the past 120,000 years. Nature, 419 , 207214.

  • Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108 , 4407. doi:10.1029/2002JD002670.

    • Search Google Scholar
    • Export Citation
  • Renssen, H., H. Goosse, and T. Fichefet, 2002: Modeling the effect of freshwater pulses on the early Holocene climate: The influence of high-frequency climate variability. Paleoceanography, 17 , 1020. doi:10.1029/2001PA000649.

    • Search Google Scholar
    • Export Citation
  • Schlesinger, M. E., and N. Ramankutty, 1994: An oscillation in the global climate system of period 65–70 years. Nature, 367 , 723726.

    • Search Google Scholar
    • Export Citation
  • Smith, T. M., and R. W. Reynolds, 2004: Improved extended reconstruction of SST (1854–1997). J. Climate, 17 , 24662477.

  • Smith, T. M., R. W. Reynolds, T. C. Peterson, and J. Lawrimore, 2008: Improvements to NOAA’s historical merged land–ocean surface temperature analysis (1880–2006). J. Climate, 21 , 22832296.

    • Search Google Scholar
    • Export Citation
  • Steig, E. J., and Coauthors, 1998: Synchronous climate changes in Antarctica and the North Atlantic. Science, 282 , 9295.

  • Stocker, T. F., and D. C. Wright, 1991: Rapid transitions of the ocean’s deep circulation induced by changes in surface water fluxes. Nature, 27 , 729732.

    • Search Google Scholar
    • Export Citation
  • Stocker, T. F., and S. J. Johnsen, 2003: A minimum thermodynamic model for the bipolar seesaw. Paleoceanography, 18 , 1087. doi:10.1029/2003PA000920.

    • Search Google Scholar
    • Export Citation
  • Stommel, H., 1961: Thermohaline convection with two stable regimes of flow. Tellus, 13 , 224230.

  • Stouffer, R. J., S. Manabe, and K. Bryan, 1989: Interhemispheric asymmetry in climate response to a gradual increase of atmospheric CO2. Nature, 342 , 660662.

    • Search Google Scholar
    • Export Citation
  • Stouffer, R. J., and Coauthors, 2006: Investigating the causes of the response of the thermohaline circulation to past and future climate changes. J. Climate, 19 , 13651387.

    • Search Google Scholar
    • Export Citation
  • Tziperman, E., 1997: Inherently unstable climate behaviour due to weak thermohaline ocean circulation. Nature, 386 , 592595.

  • von Storch, H. V., and F. W. Zwiers, 1999: Statistical Analysis in Climate Research. Cambridge University Press, 484 pp.

  • Yu, E-F., R. Francois, and M. P. Bacon, 1996: Similar rates of modern and last-glacial ocean thermohaline circulation inferred from radiochemical data. Nature, 379 , 689694.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 21 21 21
PDF Downloads 12 12 12

Evidence for Two Distinct Modes of Large-Scale Ocean Circulation Changes over the Last Century

View More View Less
  • 1 Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany, and Faculty of Physics, University of Bucharest, Bucharest, Romania
  • | 2 Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Restricted access

Abstract

Through its nonlinear dynamics and involvement in past abrupt climate shifts the thermohaline circulation (THC) represents a key element for the understanding of rapid climate changes. The expected THC weakening under global warming is characterized by large uncertainties, and it is therefore of significant importance to identify ocean circulation changes over the last century. By applying various statistical techniques on two global sea surface temperature datasets two THC-related modes are separated. The first one involves relatively slow adjustment of the whole conveyor belt circulation and has an interhemispherically symmetric pattern. The second mode is associated with the relatively fast adjustment of the North Atlantic overturning cell and has the seesaw structure. Based on the separation of these two patterns the authors show that the global conveyor has been weakening since the late 1930s and that the North Atlantic overturning cell suffered an abrupt shift around 1970. The distinction between the two modes provides also a new frame for interpreting past abrupt climate changes.

Corresponding author address: Dr. Mihai Dima, University of Bucharest, Faculty of Physics, Department of Atmospheric Physics, CP MG-11, Magurele, Str. Atomistilor 405, Bucharest, Romania. Email: mihai@dmn.ro

Abstract

Through its nonlinear dynamics and involvement in past abrupt climate shifts the thermohaline circulation (THC) represents a key element for the understanding of rapid climate changes. The expected THC weakening under global warming is characterized by large uncertainties, and it is therefore of significant importance to identify ocean circulation changes over the last century. By applying various statistical techniques on two global sea surface temperature datasets two THC-related modes are separated. The first one involves relatively slow adjustment of the whole conveyor belt circulation and has an interhemispherically symmetric pattern. The second mode is associated with the relatively fast adjustment of the North Atlantic overturning cell and has the seesaw structure. Based on the separation of these two patterns the authors show that the global conveyor has been weakening since the late 1930s and that the North Atlantic overturning cell suffered an abrupt shift around 1970. The distinction between the two modes provides also a new frame for interpreting past abrupt climate changes.

Corresponding author address: Dr. Mihai Dima, University of Bucharest, Faculty of Physics, Department of Atmospheric Physics, CP MG-11, Magurele, Str. Atomistilor 405, Bucharest, Romania. Email: mihai@dmn.ro

Save