Why is climate sensitivity so unpredictable?

Science

Volumn 318, Issue 5850, 2007, Pages 629-632

  Roe, Gerard H ^a   Baker, Marcia B ^a  

^a UNIVERSITY OF WASHINGTON   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON DIOXIDE; CLIMATE CHANGE; CLIMATE CONDITIONS; CLIMATE MODELING; UNCERTAINTY ANALYSIS;

ACCURACY; ARTICLE; CLIMATE; CLIMATE CHANGE; FORECASTING; METEOROLOGY; PREDICTION; PRIORITY JOURNAL; TEMPERATURE;

EID: 35548966746     PISSN: 00368075     EISSN: 10959203     Source Type: Journal    
DOI: 10.1126/science.1144735     Document Type: Article

References (30)

1. S. Solomon et al., Eds. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge Univ. Press, 2007).
2. Climate sensitivity is a measure of equilibrium climate change. During the adjustment to the new equilibrium, time-dependent factors, in particular ocean heat uptake, are also important.
3. M. R. Allen et al., in Avoiding Dangerous Climate Change, H. J. Schellnhuber, W. Cramer, N. Nakicenovic, T. Wigley, G. Yohe, Eds. (Cambridge Univ. Press, 2006), pp. 281-289.
4. N. G. Andronova, M. E. Schlesinger, J. Geophys. Res. 106, 22605 (2001).
5. J. M. Gregory, R. J. Stouffer, S. C. B. Raper, P. A. Stott, N. A. Rayner, J. Clim. 15, 3117 (2002).
6. C. E. Forest, P. H. Stone, A. P. Sokolov, M. R. Allen, M. D. Webster, Science 295, 113 (2002).
7. D. J. Frame et al., Geophys. Res. Lett. 32, L09702 (2005).
8. J. M. Murphy et al., Nature 430, 768 (2004).
9. D. A. Stainforth et al., Nature 433, 403 (2005).
10. B. M. Sanderson, C. Piani, W. J. Ingram, D. A. Stone, M. R. Allen, Clim. Dyn. published online 3 July 2007; 10.1007/s00382-007-0280-7, in press.
11. G. C. Hegerl, T. J. Crowley, W. T. Hyde, D. J. Frame, Nature 440, 1029 (2006).
12. D. L. Royer, R. A. Berner, J. Park, Nature 446, 530 (2007).
13. C. Piani, D. J. Frame, D. A. Stainforth, M. R. Allen, Geophys. Res. Lett. 32, L23825 (2005).
14. S. Bony et al., J. Clim. 19, 3445 (2006).
15. There are ambiguities surrounding feedback terminology in the climate literature. Hansen et al. (22) reversed the definition of feedback factor and gain from what is conventional in electronics (23-25). The convention adopted by Hansen et al. (22) has permeated much, but not all, of the climate literature [compare with (26-28)]. For the standard electronics definitions, it can be shown that the feedback factor is proportional to the fraction of the system response fed back into the system input and that the gain is the proportion by which the output has gained (i.e., been amplified) by the inclusion of the feedbacks. In this study, we retain the traditional electronics definitions. See also the SOM.
16. 0 is found by calculating the climate response to forcing, allowing only surface temperature to change (17, 18, 22).
17. R. Colman, Clim. Dyn. 20, 865 (2003).
18. B. J. Soden, I. M. Held, J. Clim. 19, 3354 (2006).
19. Researchers (17, 18) estimated mean and SD of feedback factors calculated from two different suites of climate models. First, Colman (17) found a mean and SD of (0.11, 0.06) for the albedo feedback factor; (0.17, 0.11) for the cloud feedback factor; and (0.42, 0.06) for the water vapor and lapse rate feedbacks combined. Second, Soden and Held (18) found a mean and SD of (0.09, 0.02) for the albedo feedback factor; (0.22, 0.12) for the cloud feedback factor; and (0.31, 0.04) for the water vapor and lapse rate feedbacks combined. The water vapor and lapse rate feedbacks are typically combined because models show a strong negative correlation between the two. Although the combined feedback for water vapor and lapse rate has the largest magnitude, the greatest contributor to uncertainty is the cloud feedback.
20. P. F. Hoffman, D. P. Schrag, Terra Nova 14, 129 (2002).
21. L. C. Sloan, D. K. Rea, Palaeogeogr. Palaeoclimatol. Palaeoecol. 119, 275 (1996).
22. J. E. Hansen et al., in Climate Processes and Climate Sensitivity, J. E. Hansen, T. Takahashi, Eds. (Geophysical Monograph 29, American Geophysical Union, Washington, DC, 1984), pp. 130-163.
23. H. W. Bode, Network Analysis and Feedback Amplifier Design (Van Nostrand, New York, 1945).
24. R. Kories, H. Schmidt-Walter, Electrical Engineering: A Pocket Reference (Springer, Berlin, 2003).
25. J. G. Graeme, Optimizing Op-Amp Performance (McGraw-Hill, New York, 1997).
26. National Research Council, Understanding Climate Change Feedbacks (National Academies Press, Washington, DC, 2003).
27. R. S. Lindzen, M.-D. Chou, A. Y. Hou, Bull. Am. Meteorol. Soc. 82, 417 (2001).
28. J. M. Wallace, P. V. Hobbs, Atmospheric Science: An Introductory Survey (Academic Press, San Diego, ed. 2, 2006).
29. The curve from (5) is a numerical calculation from climate observations and uses an equation isomorphic to Eq. 3.
30. We thank P. Guttorp, J. M. Wallace, D. Hartmann, D. Battisti, C. Bretherton, E. Steig, D. Stolar, and S. Warren for insightful comments on drafts of the manuscript; M. R. Allen, M. Cane, and one anonymous reviewer for constructive suggestions that substantially improved the manuscript; and H. J. Smith, the editor. G.H.R. thanks Yale University for support as a Flint Visiting Professor.