Although below the model ECS of 2.3 C, that is very close to the GISS - E2 - R effective climate sensitivity of ~ 2 C, which is what this method would estimate if the forcing were purely from CO2. (climateaudit.org)
But what I actually wrote was that in GISS - E2 - R effective climate sensitivity increases with time since the forcing was applied, as it does in many GCMs. (climateaudit.org)
In particular, «[t] hese 19 tuned simple model versions have effective climate sensitivities in the range 1.9 °C to 5.9 °C.» (climateaudit.org)