There are two notions of ECS. The first is without feedbacks (mainly water vapor and clouds). It estimates a simple non-condensing gas CO2 doubling. AR4 implicitly had that at a 1.1C. Lindzen’s 2012 curve reproduced below used ~1.2C. Using Monckton’s equation and his parameters yields 1.16C, so one can legitimately argue Lindzen’s following curve merely rounds up given uncertainty.