If by accurate, you mean that the GCM's predicted that dumping massive amounts of aersols into the atmosphere would cause cooling, I am not impressed. (realclimate.org)
2) More importantly, the virtual elimination of stratospheric aersols over that interval represents a strong positive forcing. (skepticalscience.com)
One typical approach is to adjust one parameter (say aersols) to get closure at TOA. (judithcurry.com)