Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model

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Urban, Nathan M. ; Keller, Klaus (2010)

How has the Atlantic Meridional Overturning Circulation (AMOC) varied over the past centuries and what is the risk of an anthropogenic AMOC collapse? We report probabilistic projections of the future climate which improve on previous AMOC projection studies by (i) greatly expanding the considered observational constraints and (ii) carefully sampling the tail areas of the parameter probability distribution function (pdf). We use a Bayesian inversion to constrain a simple model of the coupled climate, carbon cycle and AMOC systems using observations to derive multicentury hindcasts and projections. Our hindcasts show considerable skill in representing the observational constraints. We show that robust AMOC risk estimates can require carefully sampling the parameter pdfs. We find a low probability of experiencing an AMOC collapse within the 21st century for a business-as-usual emissions scenario. The probability of experiencing an AMOC collapse within two centuries is 1/10. The probability of crossing a forcing threshold and triggering a future AMOC collapse (by 2300) is approximately 1/30 in the 21st century and over 1/3 in the 22nd. Given the simplicity of the model structure and uncertainty in the forcing assumptions, our analysis should be considered a proof of concept and the quantitative conclusions subject to severe caveats.
  • References (73)
    73 references, page 1 of 8

    Adger, N., Aggarwal, P., Agrawala, S., Alcamo, J., Allali, A. and coauthors. 2007. Climate Change 2007: Impacts, Adaptation and Vulnerability, Summary for Policymakers. IPCC Secretariat, c/o WMO, 7bis, Avenue de la Paix, C.P. N ◦ 2300, 1211 Geneva 2, Switzerland.

    Alley, R., Berntsen, T., Bindoff, N. L., Chen, Z., Chidthaisong, A. and co-authors. 2007. Climate Change 2007: The Physical Science Basis, Summary for Policymakers. IPCC Secretariat, c/o WMO, 7bis, Avenue de la Paix, C.P. N ◦ 2300, 1211 Geneva 2, Switzerland.

    Annan, J. D. and Hargreaves, J. C. 2009. On the generation and interpretation of probabilistic estimates of climate sensitivity. Clim. Change. doi:10.1007/s10584-009-9715-y.

    Annan, J. D., Hargreaves, J. C., Ohgaito, R., Abe-Ouchi, A. and Emori, S. 2005. Efficiently constraining climate sensitivity with paleoclimate simulations. Scient. Online Lett. Atmos. 1, 181-184.

    Baumgartner, A. and Reichel, E. 1975. The World Water Balance. Elsevier, Amsterdam, the Netherlands, and New York.

    Bence, J. R. 1995. Analysis of short time series: correcting for autocorrelation. Ecology 76, 628-639.

    Boden, T. A., Marland, G. and Andres, R. J. 2009. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, TN, U.S.A. doi:10.3334/CDIAC/00001. Available electronically from: http://cdiac.ornl.gov/trends/emis/overview_2006.html.

    Broecker, W. S. 1991. The great ocean conveyor. Oceanography 4, 79-89.

    Brohan, P., Kennedy, J. J., Harris, I., Tett, S. F. B. and Jones, P. D. 2006. Uncertainty estimates in regional and global observed temperature changes: a new data set from 1850. J. Geophys. Res.-Atmos. 111, D12106, doi:10.1029/2005JD006548.

    Bryden, H. L., Longworth, H. R. and Cunningham, S. A. 2005. Slowing of the Atlantic meridional overturning circulation at 25◦ N. Nature 438(7068), 655-657.

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