It's a problem if the folks DOING the systems modeling actually LOOK at all those things as "forcings".. In a complex system with feedbacks and storage and delays, that measure "energy balance" resulting in a surface temp change, the only primary energy ENTERING the system (in this case) is the solar forcing and some trivial contributions such as plate tectonics, atmospheric friction, and planetary "wobble". Then you have adjustments to "transfer functions" that change dynamically which affect HOW that primary energy gets, distributed, stored or delayed.
The best "handle" on transfer functions are the "solar constant" (which is NOT constant when searching for such small results) and the effect of the GHGases. Both of these are pretty well (but not completely) specified by basic chemistry and physics and observation. The OTHER things you mentioned are less well "modeled". Because of serious lack of knowledge about the feedbacks, delays, and storage.
For instance, the GHGases dont ADD any energy to the overall system other than what they put into storage. They IMPEDE the NET LOSS of energy to space. And if you look back at the "famous" Trenberth "energy" diagram where he took all of this on the back on an envelope (uncertainties and all) and MIRACULOUSLY discovered the EXACT amount of trivial energy to account for all the warming by the path thru the GHGases

, he left out one of the most IMPORTANT aspects of this transfer function. And that was "ocean storage" of the "excess heat" created by additional "atmospheric insulation". About 20 years LATER --- he co-authors a paper about "How the Oceans Ate My Global Warming" by making the claim that a full 90% of the EXCESS HEAT created by the heat retardardation to space ended up as storage in the DEEP oceans. Yet at the time he pulled off that miraculous envelope exercise -- he completely left that component OUT of his "balance".. He simply considered the "back radiation" of the GHGases as a simple "forcing" without accounting for complexity of that particular transfer function that ACTS on changes in that one variable.
In addition, because the GHG effect doesn't ADD any primary energy into the system -- you need to account for the ATMOSPHERIC storage of that energy as well as the ocean and any land storage. Because OBVIOUSLY if the effect of higher GHGases is to RETAIN ENERGY at the surface -- it must be "stored" somewhere right? Do you know the what the "storage capacity" is of an additional 120ppm of CO2 in the atmosphere is? What is the retention time of that storage. Etc, Etc..
Bottom line is --- it's not a forcing in the traditional "systems theory" terminology -- is it?
It's a technical observation. Not ready for public education. But it shows how juvenile and sloppy it was to allow the public to THINK for nearly 20 years --- that CO2/CH4 emissions was the MASTER TUNING KNOB for this complex system.. It isn't..
Since you said you have an engineering background -- I didn't hold back. Hope you understand my skepticism about some of the whackier "pronouncements" that have come from the AGW circus..
Okay, I've read that thing thrice now, and still don't really understand your problem.
If you add insulation to your house, and the heater (the sun) keeps running at the same rate, the new equilibrium will show there's more heat in the house (system). So, in that sense, GHGs (insulation) "add" energy to the system. I believe we agree on that, even if the process of heat retention is different from heat creation in, say, a stove.
Moreover, since you're perennially bashing poor Trenberth: The earth's heat content (let's leave out minor factors such as heating by the earth's molten core, etc.) is determined by solar irradiation minus the sum of all radiation to space. That alone gives you the changes in energy content. Where any excess heat ends up being stored affects the internal dynamics, but not the overall heat content. That's why Trenberth could leave out ocean storage and still come up with a pretty accurate figure. Moreover, the cleverly dubbed "How the Oceans Ate My Global Warming" forgets that the oceans are pretty much part of the globe, and thus a part of "Global Warming", very much so. So, when oceans are storing heat away in deeper regions, and land surface temperatures don't budge much, "global warming" still hasn't stopped. So, the much celebrated "Hiatus" or "Pause" was just bogus nonsense based on the difficulty to find the excess heat, and the ubiquitous reliance on cherry-picking beginning and end dates subsequent to the 1998 El Niño..
So, yes, heat retention by GHGs is somewhat different from solar irradiation. Unless you come up with another, better term for that former aspect of forcing (which I am convinced it is), I cannot see anything in this whole exercise other than nitpicking over mere words.
"But it shows how juvenile and sloppy it was to allow the public to THINK for nearly 20 years --- that CO2/CH4 emissions was the MASTER TUNING KNOB for this complex system.. It isn't.."
All I read points to CO
2 as the main driver of warming at the time, methane playing a comparatively minor role (for the time being). Whether that translates to "MASTER TUNING KNOB" I patently don't know. I also don't know whether in a complex system such as the earth's climate there is a MASTER TUNING KNOB, or whether it was actually sloppy to allow the public think there is one. Global warming is real, CO
2 is its main driver, reducing carbon emissions should be our main environmental policy aim, and it does not make one whit of a difference to me whether we call it a "MASTER TUNING KNOB" or humankind's self-destructive addiction to fossil fuels or whatever.
As to this:
"Do you know the what the "storage capacity" is of an additional 120ppm of CO2 in the atmosphere is?"
Of course, CO
2 molecules hit by IR radiation transfer energy by way of collisions to nearby N
2 or O
2 molecules, so the storage capacity of "an additional 120ppm of CO2 in the atmosphere" is of no import. Rather, raising the question appears to indicate a misunderstanding on your part.
I don't think I've ever spoken about my background, as I don't think that our contributions should be judged according to any such claimed, unverified background. As to being wary of wacky pronouncements, yep, there's something to that. You won't be surprised to learn that I am locating the predominant source of such pronouncements in the other corner, eh?