First of all, CSALT has little to do with what I am doing with fitting the ENSO factors via differential equations, so I don't want to conflate the two.

CSALT is more of a phenomenological approach to explaining the global temperature record trends by composing via known factors, and one of these happens to be an ENSO index.

The LOD factor (the L in CSALT) is an interesting one, because we know that any changes in the earth's rotational speed has to impact the internal energy in some way. It was the idea of J. Dickey and others at JPL to associate those changes with long-term changes in the surface temperature. No one had tried incorporating that as a variate along with the other known variates, which is what makes it a bit different than what other climatologuists such as Foster/Rahmsdorf and Lean were doing with their multivariate approach.

J. O. Dickey, S. L. Marcus, and O. de Viron, “Air Temperature and Anthropogenic Forcing: Insights from the Solid Earth,” Journal of Climate, vol. 24, no. 2, pp. 569–574, 2011.

And the reason that I started looking at ENSO was that I realized that CSALT had less of a predictive capability as long as we could not predict ENSO. So after figuring out this ENSO thing, perhaps I will try to look in to what is causing the LOD and whether that is in fact somehow related to the multidecadal variability in temperature.

Secondly, as far as the mystery of thermodynamics, this is what Peter Ván said

"The basic mystery in thermodynamics is the universality. The validity of thermodynamic equations and theories regularly exceed the expectations."

P. Ván, “Thermodynamics of continua: the challenge of universality,” arXiv preprint arXiv:1305.3582, 2013.

Scientists routinely apply thermodynamics as a first-order approximation, and it seems to work ins spite of everyone's realization that much of the details are buried. Consider just the connection between entropy and heat capacity. I do think that nad's idea of applying the free energy of biotic activity in this formulation is a good one, unfortunately I don't have the measure for that, unlike the other factors.