The absolute percentage of the atmosphere being what you consider to be a small number is not actually relevant to what the impact of that would be. If I were t

The absolute percentage of the atmosphere being what you consider to be a small number is not actually relevant to what the impact of that would be. If I were to give you a pill of cyanide, I don’t know how comforted you’d be by me assuring you that the pill was less than 0.1% of your body mass. I’m not calling CO2 cyanide, I’m saying “because this sounds like a small absolute percentage to me” is not a salient argument. This atmospheric gas which makes up a fraction of our atmosphere is responsible for virtually all the organic mass in plant life on the planet, and consequently all animal life. If we agree that [the existence of all biomass on the planet] is not insignificant, then we agree that the small absolute percentage that CO2 represents in the total atmosphere is clearly already sufficient to be highly consequential.