Maybe You Didn't Notice
But Climate models are among if not the most complicated computer models out there for the very reasons you site. Yet the naysayers will turn around and use this trait against them claiming you can fake anything with that many variables. It is also fundamentyally ignorant or dishonest to act like the phrase "they're just computer models" as if that alone invalidated their value isn't a catch phrase for a large part of the anti-GW crowd.
see ya