As I indicated in an earlier blog, the natural variability at decadal time scales hinders the validation of
any projection against observations, as these observations reflect just one possible trend.
Not exact matches
It is of course true that careful
observation requires the use of controls, the elimination of the possibility of social cuing, guarding
against uncritical
projection of the observer's prejudices and presuppositions, etc. (MA 83 - 98).
I was interested to know whether it was appropriate to use successive 11 - year averages to test
observations against projections, and I accept your view that it's not.
Hansen
projections against satellite
observations.
In January 2008, I discussed here and here how Hansen's
projections compared
against the most recent RSS and MSU data, noting a downtick which resulted in a spread not merely between
observations and Scenario A, but between
observations and Scenario B, sometimes said to have been vindicated.
The fundamental objectionable switcheroo in such studies of sensitivity etc. is that the lead - in disclaimer is that these simulations are merely «
projections», using various what - if scenarios, and hence can not be falsified or tested
against observations.
Personally I don't expect the IPCC to find science that compares
observations against every single model
projection ever made, whereas you seem to think they ought to.