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Modeling Climate Feedbacks Based on Short-Term Climate Variations
Koumoutsaris, S. 2013. What can we learn about climate feedbacks from short-term climate variations? Tellus A 65: 10.3402/tellusa.v65i0.18887.

The author writes that "currently, global climate models disagree in their estimates of feedbacks, and this is one of the main reasons for uncertainty in future climate projections," citing Bony et al. (2006). And he further indicates that "in order to unveil the origin of these inter-model differences, model simulations need to be evaluated against observations of present climate."

What was done
Koumoutsaris estimated, as he describes it, "the feedbacks from water vapor, lapse-rate, Planck, surface albedo and clouds, using models and observations based on the climate response over the last 30 years," which short-term feedbacks "result both from external changes in the forcing (due to greenhouse gas increases, volcanic and industrial aerosol emissions) and internal climate variations (mostly due to ENSO variability)."

What was learned
In the words of the Swiss scientist, "the CMIP3 models show a much larger interdecile range for all short-term feedbacks in comparison to the long-term ones," which he says "is also the case for the three models with the most realistic ENSO representation," citing van Oldenborgh et al. (2005)." He also indicates that the models have difficulty capturing "the position and magnitude of ENSO teleconnection patterns." In addition, he reports that "the uncertainty in the cloud feedback, using a combination of reanalysis and satellite data, is still very large."

What it means
Koumoutsaris concludes that his several analyses indicate that "important aspects of the ENSO variability are still poorly understood and/or simulated." And in the case of cloud feedback, he says that it is difficult to come to "any firm conclusion" ... even on the sign of the feedback. And when these phenomena are so poorly simulated - even to the point where the direction of change of one of them remains unknown - it should be clear to all that the climate-modeling enterprise still has a long, long way to go before it can be considered good enough to serve as a basis for energy policy decisions that are already dictating various aspects of human behavior.

Bony, S., Colman, R., Kattsov, V.M., Allan, R.P., Bretherton, C.S., Dufresne, J., Hall, A., Hallegatte, S., Ingram, W., Randall, D.A., Soden, B.J., Tselioudis, G. and Webb, M.J. 2006. How well do we understand and evaluate climate change feedback processes? Journal of Climate 19: 3445-3482.

Van Oldenborgh, G.J., Philip, S.Y. and Collins, M. 2005. El Niņo in a changing climate: a multi-model study. Ocean Science 1: 81-95.

Reviewed 19 June 2013