Are you sure you didn't mean 250 ppm? That's a lot closer to what it was 200 years ago. 350 ppm is around 1990 levels and it is hard to see how 1990 levels woul

Are you sure you didn't mean 250 ppm? That's a lot closer to what it was 200 years ago. 350 ppm is around 1990 levels and it is hard to see how 1990 levels would be what life was made for.