Via Nic Lewis and Frank Bosse comes a link to a page at the Berkeley Earth Surface Temperature project (BEST). Richard Muller and his team have compared their results to the output of a series of GCMs and the results are not exactly pretty, as one of the headlines explains
Many models still struggle with overall warming; none replicate regional warming well.
As Nic explains in an email:
...the only GCM to match the BEST 20th century land trend accurately is inmcm4. It's almost spot on, whereas all the other models are out by at least 10% apart from GISS-E2-H, and far more in many cases, with the most sensitive models often showing the lowest increases (I suspect due to very high aerosol forcing and maybe low GHG forcing and/or high ocean heat uptake). The models that get the land trend most wrong are HadGEM2-ES and a model based on it, ACCESS-1.3, CSIRO-Mk3-6 and MIROC5 - all* highly sensitive models that underestimate the land trend by a factor of 2 of more - a factor of nearly 5 out in CSIRO-Mk3-6's case!
I'm unsure why BEST say that GISS-E2-H performs best for the overall trend: it is 2nd best after inmcm4 and far less accurate. Anyway, GISS-E2-H is only a bit more sensitive (ECS) than inmcm4: 2.3 vs 2.1 C, against a model average of 3.4-3.5 C.
Richard Muller once wrote a very successful book called Physics for Future Presidents; this is a man who has been at the sharp edge of the science/policy interface and at the very highest levels of government to boot.
So in the light of what BEST have found, I wonder what he would tell future presidents about GCMs. Do they have any role in the policy process at all?
*In a further email, Nic corrects himself, noting that although MIROC-ESM is the most sensitive model of all (ECS 4.7C),MIROC5 is not actually highly sensitive, having an ECS of ~2.9C.