The problem is this: if there is no significant radiative transfer of heat from the lower troposphere to the stratosphere, then any changes in CO2 concentration in the lower troposphere would not affect the temperature of the stratosphere.
Precisely.
The "standard" view is that increasing CO2 concentrations in the lower troposphere absorb increasing amounts of longwave (IR) radiation, preventing it from being radiated to the stratosphere.
Which should give rise to Tropospheric warming according to the "standard" view, NO substantial warming in the Troposphere is occuring.
That process would result in stratospheric cooling. Stratospheric cooling is, in fact, observed. Thus, you have to account for the observed stratospheric cooling. Some of it, but not all, is attributable to ozone depletion.
Nothing to prevent additional water vapor from storing latent heat, it very efficiently picks up heat in evaporation as well as broadband IR absorption. Water Vapor is a couple of orders of magnitude better heat resevoir than CO2 is, as well as the fact that most of the heat held by water vapor is latent heat of vaporization & and fusion.
CO2 is a narrow band IR absorber and its latent heat characteristics are nul as far ast the atmosphere is concerned, which is why is fails do the job.
Stored as latent heat by water vapor, there is minimal temperature rise in the Troposphere,(could even fall under some conditions), allowing the Stratosphere to cool. Which is what we observe.
For Hug and Barrett's work to be applicable, an alternative explanation for stratospheric cooling must also be provided.
All that is needed is a mechanism for heat storage, water serves quite well and can explain why the Troposphere is not heating as expected in the "standard" view, and why the Stratosphere can cool, should ozone depletion not even required to explain cooling of the Stratosphere.
The stratosphere loses heat to space, and it is to thin to absorb radiant energy released from blackbody radiation and from release of latent heat of water vapor transported to the upper atmosphere.
To which I replied via query about the observed warming of the stratosphere after the Mt. Pinatubo eruption.
Your reply: The effect of volcanoes on the stratosphere has nothing to do with hypothetical CO2 concentrations increasing forcing in the Troposphere. It has a great deal to do with the aerosols injected into the stratosphere which absorb radiant energy inducing higher molecular motion(i.e. raising temperature) of the stratosphere.
So first you've said that the stratosphere is too thin to absorb radiant energy, and then you note that it isn't, i.e., the injected aerosols impart a warming via greater molecular motion. I prefer the latter. The stratosphere warms and cools radiatively. You're a physical chemist, and while I couldn't pass the maths required for Berkeley graduate school P-chem, I know enough to say this: temperature is a measurement of the kinetic energy of the molecules in a gas, liquid, or solid. Right?
OK. Now you've proposed something quite interesting, which is that water vapor can explain a lot of what's not explained. That's quite consistent with the current state of knowledge regarding clouds and water vapor in the atmosphere.
All that is needed is a mechanism for heat storage, water serves quite well and can explain why the Troposphere is not heating as expected in the "standard" view, and why the Stratosphere can cool, should ozone depletion not even required to explain cooling of the Stratosphere.
The interesting thing about this to me is that the water vapor feedback is one of the primary positive feedbacks of GHG-induced warming. So, if you've got GHG-induced warming, and a water vapor feedback, then that's pretty much in-line with the mainstream view. Your major contention is still with the CO2 energy absorption.