A recent post on the climate skeptic blog climateaudit.org showed some comparisons of the relationship between world temperature and CO₂ over the 20th century from a simple model originally published in the 1930s and a recent complex model from the UK Met Office. The simple model seemed to do a better job of predicting temperature given the CO₂ level.

The comparison chart is shown below:

Climateaudit then compared the results from many other models using a measure of predictive skill and concluded:

In addition to calculating the skill score of HadGEM2, I also calculated skill scores for the 12 CMIP5 RCP4.5 averages on file at KNMI. ... Remarkably, none of the 12 CMIP5 have any “skill” in reconstructing GLB temperature relative to the simple GCM-Q formula. Indeed, 10 of 12 do dramatically worse....

Note that this comparison is not being used here to deny climate change: the simple model predicts significant warming in the world climate (though with a lower sensitivity than typical modern models). The issue is whether complicated models of climate change do a better job than simple models.

So, is climateaudit right? Are, as many (non-climate) modellers might intuit, simple models better than complex ones in predicting average climate?