I suspect that this obvious test
of the
validity of GCMs is not emphasized in public discussions because
of the considerable influence
of people who have an unshakable belief that the earth is 5000 or so years old, such that
paleoclimate evidence is unconvincing to them.
But the most critical point to remember, if you are concerned about this for its impact on the
validity of AGW theory, is that the fight is over a single study, published eight years ago, focused on
paleoclimate.