Greenhouse effect is caused by the absorption by greenhouse gases of low frequency/ high wavelength light being reflected from the Earth's surface.
Greenhouse effect is not caused by higher heat capacity for CO2/ other greenhouse gases (with ~400 ppm CO2 the heat capacity is negligibly different from 0 ppm CO2)
This is neither controversial nor political. Check out any scientific literature.
Heat capacity is not a reservoir. It is the amount of energy it takes to heat a certain amount of material by a certain temperature (calories/ (gram degree C)
well, you've got me thinking about this again. Following my last posts yesterday I got to thinking about microwave ovens. If you irradiate water molecules with just the right IR frequency, you can spin those little water molecules and specifically heat them. That frequency corresponds to the energy of that spin, stretch or whatever motion the molecule can take with that specific energy amount.
heat capacity has been studied a lot with almost every molecule of interest to engineers designing engines, or to chemists generally.
It is a property that is a consequence of mass and chemical structure as well as electronic bonding orbitals. It is empirical in the sense that it's value is experimentally determined.... but hey we can calculate it too from known relations just knowing the molecular structure and bonding possibilities (hydrogen bonding,etc)
Temperature might be the more correct measure of heat storage, if mathematically multiplied by heat capacity figures.
I think your concept of mere absorption of IR or "low frequency/high wavelength" light coming up from the earth surface is a simplification. Not exactly untrue, just part of the story. Maybe a big part. "Greenhouse Effect" or "Greenhouse Gases" function like a blanket.
But I think you underestimate the temperature/warmth content of CO2 and water molecules in the air. Sure, they will re-radiate the heat they absorb.... but not very quick.
Black body radiation is always a fact for anything above absolute zero K. 3 degree "heat" is a huge factor in our universe, and so is the zero K heat..... the amount of heat held by material that is at absolute zero. 3 degree heat is the heat radiated from objects at the temp of 3 K.
I'm not trying to minimize the radiation Earth gives off at it's average temps. If we had no atmosphere, it would all go directly out. Even oxygen and nitrogen are huge in containing heat to moderate our climate. Our atmosphere is the reason we don't have daily lows of -200 C and highs of +200 C.... well I didn't check those numbers, it's for sure an exaggeration. Maybe 100C/-100C.