We thank Ronald Stouffer and two anonymous reviewers for their very helpful and constructive comments, which helped to significantly improve the manuscript. This work was supported by the German CLIVAR and European ENSEMBLES projects and the SFB 460. We acknowledge the international modeling groups for providing their data for analysis, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) for collecting and archiving the model data, the JSC/CLIVAR Working Group on coupled Modeling (WGCM) and their Coupled Model Intercomparison Project (CMIP) and Climate Simulation Panel for organizing the model data analysis activity, and the IPCC WG1 TSU for technical support. The IPCC Data Archive at Lawrence Livermore National Laboratory is supported by the Office of Science, U.S. Department of Energy.
Bryden, H. L., H. R. Longworth, and S. A. Cunningham, 2005: Slowing of the Atlantic meridional overturning circulation at 25°N. Nature, 438 , 655–657.
Conkright, M. E., R. A. Locarnini, H. E. Garcia, T. D. O’Brien, T. P. Boyer, C. Stephens, and J. I. Antonov, 2002: World Ocean Atlas 2001: Objective analyses, data statistics, and figures CD-ROM documentation, NOAA Internal Rep. 17, 17 pp.
Drijfhout, S. S., and W. Hazeleger, 2006: Changes in MOC and gyre-induced Atlantic Ocean heat transport. Geophys. Res. Lett., 33 .L07707, doi:10.1029/2006GL025807.
Ganachaud, A., 2003: Large-scale mass transports, water mass formation, and diffusivities estimated from World Ocean Circulation Experiment (WOCE) hydrographic data. J. Geophys. Res., 108 .3213, doi:10.1029/2002JC001565.
Ganachaud, A., and C. Wunsch, 2000: Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. Nature, 408 , 453–457.
Gnanadesikan, A., R. D. Slater, N. Gruber, and J. L. Sarmiento, 2002: Oceanic vertical exchange and new production: A comparison between models and observations. Deep-Sea Res. II, 49 , 363–401.
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.
Houghton, J. T., Y. Ding, D. J. Griggs, M. Noguer, P. J. van der Linden, X. Dai, K. Maskell, and C. A. Johnson, Eds. 2001: Climate Change 2001: The Scientific Basis. Cambridge University Press, 881 pp.
Knutti, R., T. F. Stocker, F. Joos, and G. K. Plattner, 2003: Probabilistic climate change projections using neural networks. Climate Dyn., 21 , 257–272.
Kuhlbrodt, T., A. Griesel, M. Montoya, A. Levermann, M. Hoffmann, and S. Rahmstorf, 2007: On the driving processes of the Atlantic Meridional Overturning Circulation. Rev. Geophys., in press.
Lumpkin, R., and K. Speer, 2003: Large-scale vertical and horizontal circulation in the North Atlantic Ocean. J. Phys. Oceanogr., 33 , 1902–1920.
Murphy, J. M., D. M. H. Sexton, D. N. Barnett, G. S. Jones, M. J. Webb, M. Collins, and D. A. Stainforth, 2004: Quantification of modelling uncertainties in a large ensemble of climate change simulations. Nature, 430 , 768–772.
Palmer, T. N., and Coauthors, 2004: Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER). Bull. Amer. Meteor. Soc., 85 , 853–872.
Schmittner, A., M. Latif, and B. Schneider, 2005: Model projections of the North Atlantic thermohaline circulation for the twenty-first century assessed by observations. Geophys. Res. Lett., 32 .L23710, doi:10.1029/2005GL024368.
Smethie, W. M., and R. A. Fine, 2001: Rates of North Atlantic deep water formation calculated from chlorofluorocarbon inventories. Deep-Sea Res. I, 48 , 189–215.
Stocker, T. F., and A. Schmittner, 1997: Influence of CO2 emission rates on the stability of the thermohaline circulation. Nature, 388 , 862–865.
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 , 1365–1387.
Swingedouw, D., P. Braconnot, and O. Marti, 2006: Sensitivity of the Atlantic Meridional Overturning Circulation to the melting from northern glaciers in climate change experiments. Geophys. Res. Lett., 33 .L07711, doi:10.1029/2006GL025765.
Talley, L. D., J. L. Reid, and P. E. Robbins, 2003: Data-based meridional overturning streamfunctions for the global ocean. J. Climate, 16 , 3213–3226.
Trenberth, K. E., and J. M. Caron, 2001: Estimates of meridional atmosphere and ocean heat transports. J. Climate, 14 , 3433–3443.