[dragonwriter]

> CO2 is fairly innocuous, and already makes up a large percent of the volume of air.

Its fairly innocuous at naturally occurring levels, which are not a "large percent" of the air. Nitrogen, Oxygen, and -- if you want to be extremely generous and say that "almost 1%" is "a large percent" -- Argon are the only things that have a remotely plausible case for being a large percent of the atmosphere, and together make up around 99.9%.

Carbon dioxide makes up a large percent of the remaining ~0.1%, but...