Amazing. One would think that a biologist would be aware of the carbon basis of all life, and have encountered some discussion of the carbon cycle along the way.
What I would like to see are some studies determining the minimum concentration of carbon dioxide that plants can extract from the air. When carbon dioxide drops to that minimum level, the total mass of plant life will drop so that the minimum level will be maintained. When plant biomass decreases, animal biomass will necessarily decrease.
The Earth itself is sequestering carbon dioxide and has been throughout its history; do we really, out of stupid fear of "global warming", want to hasten that process?
Strange that with all the hype about increased CO2, there is not a word about a corresponding DECREASE in O2.
Broach that to an AGW Worshiper and watch for the reaction. Priceless.