My thanks to Roger Andrews for this succinct examination of the model-data comparisons from the leaked draft of IPCC AR5. He is absolutely right to draw attention to how poorly the models do in terms of tracking changes in sea surface temperature (SST). This metric is indicative of ocean heat content (OHC), which is the more important indicator of global change (though poorly understood and measured), because the ocean is the climate object with nearly all the heat capacity.
THE IPCC’S AR5 CLIMATE MODELS – ANOTHER BUST
Roger Andrews – 1-2-2013
In each of its Assessment Reports the IPCC presents a global model-versus-observations comparison to show how good its climate models are. Its latest offering, reproduced below, appears in Figure TS-7(a) of the AR5 Draft. The Figure compares four “global mean temperature” series (HadCRUT4, GISS, NCDC and Japan Meteorological Agency) against the CMIP3 and CMIP5 climate models. At a glance, which is about all the IPCC’s average Policymaker will give it, the fit looks pretty good.
But when we dig deeper – and we don’t have to dig very far – we find that the fit is actually pretty bad.