How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Another Test of CMIP5 Models: What Problems Were Detected?
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.

What was done
The authors 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."

What was learned
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."

What it means
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 ungodly amount of money that has been spent on their development and testing over the past several decades.

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.

Reviewed 12 June 2013