Critics point to the now-acknowledged shortcomings of models that were considered authoritative as recently as three years ago. By this standard, global climate models still have some way to go. The models are getting better. Computer technology is advancing, and human understanding of how the atmosphere works is nudging forward. New factors, like clouds, water vapor, aerosols, and oceans are being factored in, and these are honing the models' accuracy.
Some people are surprised to learn that the climate is in a constant state of flux.
There was no Edenic steady state before man came along. Rather, Earth has cycled through ice ages, mini-ice ages, and epochs much hotter than even the direst warming prediction. What matters for purposes of the climate change debate is the extent to which human activity is affecting the rate of any changes in the atmospheric system. We are currently living in a relatively warm interlude in what has been a predominantly cold era. Based on current understanding of these cycles, we have passed the most recent warm crest, and we can expect another ice age within the next one to three thousand years.