Abstract
Abstract
Analyses of ocean observations and model simulations suggest that there have been considerable changes in the thermohaline circulation (THC) during the last century. These changes are likely to be the result of natural multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection. Indications of a sustained THC weakening are not seen during the last few decades. Instead, a strengthening since the 1980s is observed. The combined assessment of ocean hydrography data and model results indicates that the expected anthropogenic weakening of the THC will remain within the range of natural variability during the next several decades.
Topics

No keywords indexed for this article. Browse by subject →

References
45
[1]
Beckmann "A method for improved representation of dense water spreading over topography in geopotential-coordinate models." J. Phys. Oceanogr. (1997) 10.1175/1520-0485(1997)027<0581:amfiro>2.0.co;2
[2]
Beismann "Variability of the meridional overturning circulation of the North Atlantic: Sensitivity to overflows of dense water masses." Ocean Dyn. (2004) 10.1007/s10236-003-0088-x
[3]
Bentsen "Simulated variability of the Atlantic meridional overturning circulation." Climate Dyn. (2004) 10.1007/s00382-004-0397-x
[4]
Bjerknes, J. , 1964: Atlantic air-sea interactions. Advances in Geophysics, Vol. 10, Academic Press, 1–82. 10.1016/s0065-2687(08)60005-9
[5]
Böning "Modeling CFC inventories and formation rates of Labrador Sea Water." Geophys. Res. Lett. (2003) 10.1029/2002gl014855
[6]
Bryden "Slowing of the Atlantic meridional overturning circulation at 25°N." Nature (2005) 10.1038/nature04385
[7]
Curry "Dilution of the northern North Atlantic Ocean in recent decades." Science (2005) 10.1126/science.1109477
[8]
Curry "Oceanic transport of subpolar climate signals to mid-depth subtropical waters." Nature (1998) 10.1038/35356
[9]
da Silva, A., A. C.Young, and S.Levitus, 1994: Algorithms and Procedures. Vol. 1, Atlas of Surface Marine Data 1994, NOAA Atlas NESDIS 6, 83 pp.
[10]
Delworth "Implications of the recent trend in the Arctic/North Atlantic Oscillation for the North Atlantic thermohaline circulation." J. Climate (2000) 10.1175/1520-0442(2000)013<3721:iotrti>2.0.co;2
[11]
Dengg, J., C. W.Böning, U.Ernst, R.Redler, and A.Beckmann, 1999: Effects of an improved model representation of overflow water on the subpolar North Atlantic. International WOCE Newsletter, Vol. 37, WOCE International Project Office, Southampton, United Kingdom, 10–15.
[12]
Dickson "Rapid freshening of the deep North Atlantic Ocean over the past four decades." Nature (2002) 10.1038/416832a
[13]
Dickson "The North Atlantic Oscillation and the ocean’s response in the 1990s." ICES Mar. Sci. Symp. (2003)
[14]
Döscher "The relative importance of northern overflow and subpolar deep convection for the North Atlantic thermohaline circulation." J. Phys. Oceanogr. (1997) 10.1175/1520-0485(1997)027<1894:triono>2.0.co;2
[15]
Eden "North Atlantic interdecadal variability: Oceanic response to the North Atlantic Oscillation (1865–1997)." J. Climate (2001) 10.1175/1520-0442(2001)014<0676:naivor>2.0.co;2
[16]
Eden "Mechanism of interannual to decadal variability of the North Atlantic circulation." J. Climate (2001) 10.1175/1520-0442(2001)014<2266:moitdv>2.0.co;2
[17]
Folland "Sahel rainfall and worldwide sea temperature 1901-85." Nature (1986) 10.1038/320602a0
[18]
Gent "Isopycnal mixing in ocean circulation models." J. Phys. Oceanogr. (1990) 10.1175/1520-0485(1990)020<0150:imiocm>2.0.co;2
[19]
Getzlaff "Signal propagation related to the North Atlantic overturning." Geophys. Res. Lett. (2005) 10.1029/2004gl021002
[20]
Gregory "A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration." Geophys. Res. Lett. (2005) 10.1029/2005gl023209
[21]
Haak "Formation and propagation of great salinity anomalies." Geophys. Res. Lett. (2003) 10.1029/2003gl017065
[22]
Häkkinen "Variability of the simulated meridional heat transport in the North Atlantic for the period 1951–1993." J. Geophys. Res. (1999) 10.1029/1999jc900034
[23]
Houghton "Climate Change 2001: The Scientific Basis." (2001)
[24]
Hughes "Multiple equilibria of an asymmetric two-basin ocean model." J. Phys. Oceanogr. (1994) 10.1175/1520-0485(1994)024<0619:meoaat>2.0.co;2
[25]
Hurrell "Decadal trends in the North Atlantic Oscillation: Regional temperatures and precipitation." Science (1995) 10.1126/science.269.5224.676
[26]
Kalnay "the NCEP/NCAR 40-Year Reanalysis Project." Bull. Amer. Meteor. Soc. (1996) 10.1175/1520-0477(1996)077<0437:tnyrp>2.0.co;2
[27]
Kerr "The Atlantic conveyor may have slowed, but don’t panic yet." Science (2005) 10.1126/science.310.5753.1403
[28]
Knight "A signature of persistent natural thermohaline circulation cycles in observed climate." Geophys. Res. Lett. (2005) 10.1029/2005gl024233
[29]
Kushnir "Interdecadal variations in North Atlantic sea surface temperature and associated atmospheric conditions." J. Climate (1994) 10.1175/1520-0442(1994)007<0141:ivinas>2.0.co;2
[30]
Large, W. G., and S. G.Yeager, 2004: Diurnal to decadal global forcing for ocean and sea-ice models: The data sets and flux climatologies. NCAR Tech. Note NCAR/TN-460+STR, 105 pp.
[31]
Latif "Reconstructing, monitoring, and predicting decadal-scale changes in the North Atlantic thermohaline circulation with sea surface temperature." J. Climate (2004) 10.1175/1520-0442(2004)017<1605:rmapmc>2.0.co;2
[32]
Madec, G., P.Delecluse, M.Imbard, and C.Levy, 1998: OPA 8.1 ocean general circulation model reference manual. Note de l’IPSL, Université Pierre et Marie Curie Tech. Note 11, 91 pp. [Available from B102 T15-E5, 4 Place Jussieu, 75252 Paris CEDEX 5, France.].
[33]
Manabe "Two stable eqilibria of a coupled ocean-atmosphere model." J. Climate (1988) 10.1175/1520-0442(1988)001<0841:tseoac>2.0.co;2
[34]
Manabe "The role of thermohaline circulation in climate." Tellus (1999)
[35]
Manabe "Transient response of a coupled ocean-atmosphere model to gradual changes of atmospheric CO2. Part I: Annual mean response." J. Climate (1991) 10.1175/1520-0442(1991)004<0785:troaco>2.0.co;2
[36]
Mantua "A Pacific interdecadal climate oscillation with impacts on salmon production." Bull. Amer. Meteor. Soc. (1997) 10.1175/1520-0477(1997)078<1069:apicow>2.0.co;2
[37]
Mestaz-Nuñez "Rotated global modes of non-ENSO sea surface temperature variability." J. Climate (1999) 10.1175/1520-0442(1999)012<2734:rgmone>2.0.co;2
[38]
Pacanowski, R. , 1995: User’s guide and reference manual. GFDL Ocean Group Tech. Rep. 3, 232 pp.
[39]
Rahmstorf "On the freshwater forcing and transport of the Atlantic thermohaline circulation." Climate Dyn. (1996) 10.1007/s003820050144
[40]
Rayner "Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century." J. Geophys. Res. (2003) 10.1029/2002jd002670
[41]
Schweckendiek "Mechanisms affecting the overturning response in global warming simulations." J. Climate (2005) 10.1175/jcli3550.1
[42]
Thorpe "Mechanisms determining the Atlantic thermohaline circulation response to greenhouse gas forcing in a non-flux-adjusted coupled climate model." J. Climate (2001) 10.1175/1520-0442(2001)014<3102:mdtatc>2.0.co;2
[43]
Vellinga "Global climatic impacts of a collapse of the Atlantic thermohaline circulation." Climate Change (2002) 10.1023/a:1016168827653
[44]
Visbeck "An ocean model’s response to North Atlantic Oscillation-like wind forcing." Geophys. Res. Lett. (1998) 10.1029/1998gl900162
[45]
Wood "Changing spatial structure of the thermohaline circulation in response to atmospheric CO2 forcing in a climate model." Nature (1999) 10.1038/21170
Related

You May Also Like

Robust Responses of the Hydrological Cycle to Global Warming

Isaac M. Held, Brian J. Soden · 2006

4,119 citations

Daily High-Resolution-Blended Analyses for Sea Surface Temperature

Richard W. Reynolds, Thomas M. Smith · 2007

3,646 citations

An Improved In Situ and Satellite SST Analysis for Climate

Richard W. Reynolds, Nick A. Rayner · 2002

2,772 citations