RealClimate: Evaluation of GCM simulations with a regional focus.

Do the global climate models (GCMs) we use for describing future climate change really capture the change and variations in the region that we want to study? There are widely used tools for evaluating global climate models, such as the ESMValTool, but they don’t provide the answers that I seek.

I use GCMs to provide information about large-scale conditions, processes and phenomena in the atmosphere that I can use as predictors in downscaling future climate projections. I also want to know whether the ensemble of GCM simulations that I use provides representative statistics of the actual regional climate I’m interested in. 

We need to use ensembles of many climate model simulations

The reason for using large ensembles, rather than individual simulations, can be explained by the findings of Deser et al. (2012) who demonstrated that one model with slight differences in the atmospheric initial conditions can give widely different decadal regional outlooks due to pronounced chaotic variability. 

We cannot use traditional regression, correlations or…