This is a little summary of some climate stuff that it is important to get right. If you are a cynic like me, you also need to accept facts. The things below are facts. There may be poorly explained items, but the Bold Bits Be Facts.
Green House Gases DON’T violate the second law of thermodynamics
The second law of thermodynamics states that net heat flow can only move from hot to cold. All bodies radiate energy. If there is a warm body next to a cooler body, both radiate heat. The warm body will radiate more heat than the cooler body, hence there will be a net flow from warm to cold, hence there is no violation of the second law. As it can be shown that all bodies radiate heat, were it true that this fact violated the second law of thermodynamics, then the second law would be wrong, not the (provable) fact that all bodies radiate heat. Seeing as no one is contesting the validity of the second law, it is safe to say there is no violation.
CO2 has a real and significant greenhouse effect
I believe that the level of CO2 in the atmosphere, though seemingly small, is enough that further additions of CO2 no longer impact on climate. That is, from a climate point of view, there is a lot of CO2 in the atmosphere. The irony of this misconception is that if there were indeed “too little” CO2 in the atmosphere, small changes would have a drastic effect. This is why methane is such an important greenhouse gas.
Water DOES NOT overwhelm the effect of CO2
While water is the main reason that there are noticeable differences in day to day greenhouse effects, the impact of CO2 is additive. The massive effect of water on the greenhouse effect is seen by everyone on a humid summer night when the temperature hardly drops after the sun sets. Or on a very dry summer night when it starts to get cool even before sunset. The effect of CO2 adds to this, but CO2 does not vary as much as water does. The impact of CO2 is also less, but by no means trivial. If there were no CO2 in the atmosphere, the planet would be colder. At low levels of CO2 (lower than any the earth has likely ever seen), increases in CO2 would have a very noticeable effect on temperature, no matter how much water was present.