“Clearly, gas causes warming.”
In the exact same way insulation heats your home for free, right?
Yes, in exactly the same way. It is the author's (and yours, I presume) thesis that since gasses do not create heat, they do not contribute in any way to the temperature of the Earth.
That is clearly a false conclusion.
To be clear, I do not believe that anthropogenic CO2 is causing catastrophic global warming. But I don't deny that gasses in our atmosphere do moderate our temperature swings between daytime and nighttime.