Reply #73: The models are not validated simply by looking forward

[OKIsItJustMe]

They are also validated by "predicting" the past. If they appear to predict the past relatively well, then that indicates that they will also do a good job of predicting the future.

The models in question are not (as you suggest) 1 year old. That would be like saying Microsoft Word 2010 is untested, because it’s only one year old. Microsoft Word 2010 is simply the latest version of a 25 year old program. It’s got some new features, but at its heart it’s still the same old program.

The same goes for these computer programs. They’re based on AlGoreRhythms that have been under development for decades. 30 years ago, they gave us an idea of how much warming to expect in the future, and to date, those 30 year old predictions have proven pretty good. Since then, the models have been fleshed out more, taking more variables into account, but they’re not really giving us radically different results from what they were 30 years ago.