Of course it is BS...CO2 levels were at 5,000+ ppm during the Dino ages, today it is 385 ppm. And we're heading for an ice age LONG before we see 5,000ppm again.
It was warm, full of life and we owe almosrt all our oil and coal resources to that age. CO2 = plenty plant growth. Any commercial hot house operator can tell you about it,