Climate science deniers in the main, do not understand why models are used in science. Nor do they typically understand how they are used, or how they are constructed.
Today Wondering Willis Eschenbach demonstrated this quite well (archived here). He wrote about a recent article in Science, by Professor Alex Hall. The article was discussing the merits and limitations of using General Circulation Models (GCMs) to model regional climate change, through a process known as down-scaling.
In his article, Dr Hall describes downscaling as follows:
The concept behind downscaling is to take a coarsely resolved climate field and determine what the finer-scale structures in that field ought to be. In dynamical downscaling, GCM data are fed directly to regional models. Apart from their finer grids and regional domain, these models are similar to GCMs in that they solve Earth system equations directly with numerical techniques. Downscaling techniques also include statistical downscaling, in which empirical relationships are established between the GCM grid scale and finer scales of interest using some training data set. The relationships are then used to derive finerscale fields from the GCM data.
