12. Detection of Climate Change and Attribution of Causes
Contents
Executive Summary
12.1 Introduction
12.1.1 The Meaning of Detection and Attribution
12.1.2 Summary of the First and Second Assessment Reports
12.1.3 Developments since the Second Assessment Report
12.2 The Elements of Detection and Attribution
12.2.1 Observed Data
12.2.2 Internal Climate Variability
12.2.3 Climate Forcings and Responses
12.2.3.1 Natural climate forcing
12.2.3.2 Climatic response to natural forcing
12.2.3.3 Anthropogenic forcing
12.2.3.4 Climatic response to anthropogenic forcing
12.2.4 Some Important Statistical Considerations
12.3 Qualitative Comparison of Observed and Modelled Climate
Change
12.3.1 Introduction
12.3.2 Thermal Indicators
12.3.3 Hydrological Indicators
12.3.4 Circulation
12.3.5 Combined Evidence
12.4 Quantitative Comparison of Observed and Modelled Climate
Change
12.4.1 Simple Indices and Time-series Methods
12.4.2 Pattern Correlation Methods
12.4.2.1 Horizontal patterns
12.4.2.2 Vertical patterns
12.4.3 Optimal Fingerprint Methods
12.4.3.1 Single pattern studies
12.4.3.2 Optimal detection studies that use multiple fixed
signal patterns
12.4.3.3 Space-time studies
12.4.3.4 Summary of optimal fingerprinting studies
12.5 Remaining Uncertainties
12.6 Concluding Remarks
Appendix 12.1: Optimal Detection is Regression
Appendix 12.2: Three Approaches to Optimal Detection
Appendix 12.3: Pattern Correlation Methods
Appendix 12.4: Dimension Reduction
Appendix 12.5: Determining the Likelihood of Outcomes (p-values)
References
Co-ordinating Lead Authors
J.F.B. Mitchell, D.J. Karoly
Lead Authors
G.C. Hegerl, F.W. Zwiers, M.R. Allen, J. Marengo
Contributing Authors
V. Barros, M. Berliner, G. Boer, T. Crowley, C. Folland, M. Free, N. Gillett,
P. Groisman, J. Haigh, K. Hasselmann, P. Jones, M. Kandlikar, V. Kharin, H.
Kheshgi, T. Knutson, M. MacCracken, M. Mann, G. North, J. Risbey, A. Robock,
B. Santer, R. Schnur, C. Schönwiese, D. Sexton, P. Stott, S. Tett, K. Vinnikov,
T. Wigley
Review Editors
F. Semazzi, J. Zillman
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