As for his question, if you use the forcings from AR5 AII Table 1.2 (which are a little higher than CO2 forcing alone), & the global numbers@359 (but assuming 0.86 W / m2 imbalance) you get an ECS = 2.8 ºC but most folk
consider energy balance methods do underestimate ECS.
But the point is that huge changes can happen that have local causes and are totally invisible to the
global energy balance method that is Webby's bread and butter and often used by climate scientists to argue about forcings.