On the Fact that the Cambrian Explosion Took Place at a Time When the Atmospheric CO2 Levels Were Close to 7,000 Parts-per-Million (17.5 Times Higher than They Currently Are) - https://www.youtube.com/watch?v=vrJRmIvHF0k&t=180s

So much for life not being able to flourish on earth due to high CO levels. Ouch, huh?