Santer, B. D., Painter, J. F. , Mears, C. A., Doutriaux, C., Caldwell, P., Arblaster, J. M., Cameron-Smith, P. J., Gillett, N. P., Gleckler, P. J., Lanzante, J., Perlwitz, J., Solomon, S., Stott, P. A., Taylor, K. E., Terray, L., Thorne, P. W., Wehner, M. F., Wentz, F. J., Wigley, T. M. L. , Wilcox, L. J. and Zou, C.-Z.
Identifying human influences on atmospheric temperature.
Proceedings of the National Academy of Sciences of the United States of America, 110 (1).
To link to this article DOI: 10.1073/pnas.1210514109
We perform a multimodel detection and attribution study with climate model simulation output and satellite-based measurements of tropospheric and stratospheric temperature change. We use simulation output from 20 climate models participating in phase 5 of the Coupled Model Intercomparison Project. This multimodel archive provides estimates of the signal pattern in response to combined anthropogenic and natural external forcing (the ﬁnger-print) and the noise of internally generated variability. Using these estimates, we calculate signal-to-noise (S/N) ratios to quantify the strength of the ﬁngerprint in the observations relative to ﬁngerprint strength in natural climate noise. For changes in lower stratospheric temperature between 1979 and 2011, S/N ratios vary from 26 to 36, depending on the choice of observational dataset. In the lower troposphere, the ﬁngerprint strength in observations is smaller, but S/N ratios are still signiﬁcant at the 1% level or better, and range from three to eight. We ﬁnd no evidence that these ratios are spuriously inﬂated by model variability errors. After removing all global mean signals, model ﬁngerprints remain identiﬁable in 70% of the tests involving tropospheric temperature changes. Despite such agreement in the large-scale features of model and observed geographical patterns of atmospheric temperature change, most models do not replicate the size of the observed changes. On average, the models analyzed underestimate the observed cooling of the lower stratosphere and overestimate the warming of the troposphere. Although the precise causes of such differences are unclear, model biases in lower stratospheric temperature trends are likely to be reduced by more realistic treatment of stratospheric ozone depletion and volcanic aerosol forcing.
|Date Deposited:||17 Dec 2012 09:33|
|Last Modified:||16 Jul 2015 07:53|
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