As noted in an earlier post, I’ve now managed to synchronize 48 of 49 Santer tropo series with KNMI surface temperature series and have looked at versions of some key figures in CCSP 1-1 and previously inaccessible figures in Santer.
First here is an important figure from CCP 1-1 showing a histogram of relative trends (surface minus T2LT) for models, together with observations (RSS and UAH T2LT versus CRU and NOAA/GISS). CCSP stated in the caption that “each histogram is based on results from 49 individual realizations of the 20CEN experiment, performed with 19 different models (Table
5.1)”. These are the same numbers as in Santer et al 2005 and Santer et al 2008. The “Convening Lead Author” of this CCSP section, to no surprise, turns out to be Santer himself. So I think that we can prima facie assume that Santer did the same amount of “independent” due diligence on Santer et al 2005 as Mann, in his capacity as IPCC TAR lead author, did on MBH98.
Figure 1. CCSP 1.1 Figure 5.3G, showing a histogram of T_surface minus T2LT trends, against corresponding observed trends for RSS and UAH T2LT versus CRU (lowest line) and NOAA (upper line). GISS said by CCSP to be close to NOAA.
Next here is my attempt to replicate this figure from my laborious matching of surface and Santer T2LT information. It’s quite close, but it’s a bit different. I’ve used 48 models as opposed to 49 – I was unable to match one CCSM3.0 model with a KNMI surface series; I truncated the Santer-screwed up version of CNM3.0 before 1965. I got a few more outliers than shown in the CCSP report. I got three runs with trends in lapse rate more negative than -0.1 deg C/decade – these result from highly positive model runs in the singleton Canadian CGCM3.1 run, in the singleton HadGEM1 run and in a GFDL2.1 run. I didn’t get a run above 0.05 and only got three positive runs i.e. runs with low T2LT trends relative to surface: a singleton run from INM CM3, a singleton from MRI hi-res and a MRI med-res run. As bridge players know, singletons are not incidental. No models overlap CRU minus UAH T2LT (or UAH T2) in my calculation – CCSP shows one overlap. My observational trends show differences up to 2009 (while model trends are only to 1999). As Santer says in his SI, it’s reasonable to project the model trends forward. (AIB runs where available may be another alternative.)
As an exercise, I did a similar plot for the T2 lapse rate, which proved to yield less favorable results for the CCSP consistency argument, as you can see below. In this case, no models overlapped GISS minus RSS_T2 and only one model (INM CM3.0) overlapped CRU minus RSS_T2.
It definitely seems odd that they argue so strenuously that there is no “statistical” inconsistency between models and observations.
Tomorrow I’ll continue the parsing of these results for individuals models, re-visiting Santer et al 2008.