But if the Sun burns fuel and produces heat, and then radiates that heat to Earth, then the Earth's temperature is not quite a closed system. Certainly it could be a system in equilibrium if the heat added to Earth by the Sun equals the heat lost to radiation into space. But that's the issue, isn't it?
If man does something to increase our heat retention, then the constant addition of solar radiation might cause global temperatures to rise. I do not see how the Second Law of Thermodynamics would make such a possibility impossible.
Now, let me be clear: I do not believe that mankind is capable of increasing the heat retention of the world. I think we are in equilibrium and that we will stay in equilibrium. That's my opinion.
I don't see why the Second Law is relevant at all -- but perhaps I'm missing something.
Like I said, I may be wrong. I don't quite see the correlation and he certainly didn't provide any. I gave it my best shot.
The Earth can only 'retain' so much heat, and the ozone holes might have an influence on that retention variable, and they are controlled solely by the output of the Sun. Too much, they get smaller, too little they get bigger. Self-regulating and not based on CO2.
So, like you, IMHO the effects of CO2 are insignificant compared to the changes in energy from the Sun, and the self-regulating operation of the ozone holes, and the movement of moisture from the ground to air to ground caused by... the Sun.