"Off course noncomputer handwaiving based models that predict plant growth will absorb excess CO2 are better despite actual data indicating otherwise."
It's not an issue of better. Plant growth is a variable which must be included

"While I typically dislike Bowser's right versus left slant on things (they're both wrong much of the time) he is quite correct that models are NEVER exact. One among many issues you have repeatedly ignored. "

No, Bowser is simply wrong, it's got nothing to do with Left vs Right. Models must be accurate enough to predict the real world, otherwise they are simply video games.

"What should be debated is the degree of accuracy required and how to weigh the risks of taking action versus the risks of inaction, but to do that you and others would actually have to admit that there are real risks associated with global warming."

The degree of accuracy required is the ability of the computer model to predict (not simply depict) the real world. Now even if the computer model isn't that accurate, it can help by pointing information which could be found in the real world. E.g. In studying computer models of thunderstorms researchers can find out possible phenomena in which to look for in real thunderstorms. This process of using of using computer models lowers the cost of studying things, and helps to improve the computer models.