"That, of course, doesn't negate the clear and well understood impact of greenhouse gasses, to create warming, and the impact of that on climate broadly and on factors like precipitation, glacier loss and sea level rise. Even simple models from 30 or more years ago make pretty good predictions of temperature rise that we've seen to date. "
Well, that may be true as a general assumption but is it useful for predicting real world regional climate ? Anyone can make the broad statement that IF the level of forcing for GHG theory is valid then all sorts of climate changes will occur, varying depending on regional factors.
However, for example, should those in Nth America or UK or Europe be preparing for unprecedented warming in Summer and unprecedented cold snaps in Winter ? Existing climate models suggested that along with general global warming would be a reduction in the severity of Winters. This is now recognized as a false assumption. In those regions, severe cold snaps pose a greater threat than reasonably warmer Summers.
I recently read a paper claiming to show how early models were more accurate than appeared .. after adjustments were made for real world parameter assumptions ... which were wrongly ascribed. That may be a mathematical validation but what use are models for prediction, if they are so limited by "confidence" and assumptions as to be nothing but a guess interpreted according to bias ?
This would not be an issue except the predictions of the models are used to formulate very expensive public policy regarding GHG emissions.
