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Another Test of CMIP5 Models: What Problems Were Detected?

Reference
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. 2013. Identifying human influences on atmospheric temperature. Proceedings of the National Academy of Sciences USA 110: 26-33.
Authors Santer et al. (2013) performed "a multimodel detection and attribution study with climate model simulation output and satellite-based measurements of tropospheric and stratospheric temperature change," using "simulation output from 20 climate models participating in phase 5 of the Coupled Model Intercomparison Project [CMIP5]," which "provides estimates of the signal pattern in response to combined anthropogenic and natural external forcing and the noise of internally generated variability."

Among other things, the 21 researchers report that "most models do not replicate the size of the observed changes," in that "the models analyzed underestimate the observed cooling of the lower stratosphere and overestimate the warming of the troposphere," where warming, in their opinion (Santer et al., 2003; Hansen et al., 2005), "is mainly driven by human-caused increases in well-mixed greenhouse gases," and where "CMIP5 estimates of variability on 5- to 20-year timescales are (on average) 55-69% larger than in observations."

Speculating somewhat, one could well conclude that the models are not quite there yet, in terms of where one would logically hope they would be, in light of the tremendous amount of time, money, and effort that has been spent on their development and testing over the past several decades.

Additional References
Hansen, J.E., Sato M., Ruedy, R., Nazarenko, L., Lacis, A., Schmidt, G.A., Russell, G., Aleinov, I., Bauer, S., Bell, N., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Del Genio, A., Faluvegi, G., Fleming, E., Friend, A., Hall, T., Jackman, C., Kelley, M., Kiang, N., Koch, D., Lean, J., Lerner, J., Lo, K., Menon, S., Miller, R., Minnis, P., Novakov, T., Oinas, V., Perlwitz, Ja., Perlwitz, Ju., Rind, D., Romanou, A., Shindell, D., Stone, P., Sun, S., Tausnev, N., Thresher, D., Wielicki, B., Wong, T., Yao, M. and Zhang, S. 2005. Efficacy of climate forcings. Journal of Geophysical Research 110: 10.1029/2005JD005776.

Santer, B.D., Wehner, M.F., Wigley, T.M.L., Sausen, R., Meehl, G.A., Taylor, K.E., Ammann, C., Arblaster, J., Washington, W.M., Boyle, J.S. and Bruggemann, W. 2003. Contributions of anthropogenic and natural forcing to recent tropopause height changes. Science 301: 479-483.

Archived 18 June 2013