One of the defenses often used by climate modelers against charges that climate is simple to complex to model accurately is that “they do it all the time in finance and economics.” This comes today from Megan McArdle on economic forecasting:
I find this pretty underwhelming, since private forecasters also unanimously think they can make forecasts, a belief which turns out to be not very well supported. More than one analysis of these sorts of forecasts has found them not much better than random chance, and especially prone to miss major structural changes in the economy. Just because toggling a given variable in their model means that you produce a given outcome, does not mean you can assume that these results will be replicated in the real world. The poor history of forecasting definitionally means that these models are missing a lot of information, and poorly understood feedback effects.
Sounds familiar, huh? I echoed these sentiments in a comparison of economic and climate forecasting here.