I was playing with so simple linear regressions more to aggravate some of the minions than to really accomplish anything. I am pretty positive there is a fairly larger range of undecipherable climate noise. Some might call it chaos, but any simple control system has a range around a set point. If you want to reduce that range you are looking at big bucks and potential instability. It is simpler and more cost effective to "live" with a reasonable amount of fluctuation unless you have a very temperamental process. Having worked with "novel" new control schemes like PDI feed forward, I have witness some spectacular initial failures. Most of these types of control systems are viable now with more and faster computing power, but for simple things like HVAC control at the time they were a huge waste of money. The average person cannot sense a temperature change of less than 2 F and there is no "ideal" temperature range for all people so a half degree to degree of "slop" for indoor air temperature control is perfectly acceptable. Even a larger range of humidity control is acceptable and with proper system sizing, pretty much takes care of itself.
There are cases where more precision is required and the cost is justified, but proper load sizing as staging can reduced the complexity required for even those cases. Simple isn't a bad thing.
Since I am fairly certain that tropical convection and cloud cover trigger around 28C to produce significant negative feedback, the intersect of the linear regression and pre-LIA range are a pretty good illustration of what I expect climate to do. That would be crab sideways with a fluctuation of around +/-0.5 C degrees. So this is my prediction of the month.
So there is the title of the post, "circumstantial" evidence of a secular trend related to LIA recovery.