[Buckeye McFrog]

I believe a fact check will reveal it actually peaked in some prehistoric era when dinosaurs roamed the Earth.

[thackney]

If the CO2 is released from burning fossil fuels,

and the fossil fuels are from decayed biological matter,

and that biological matter gathered the carbon by pulling it out of the CO2 in the atmosphere,

it is pretty tough to follow that argument anywhere but to conclude the CO2 levels in the air used to be far higher.