Liebig's Law of the Minimum describes why you can't count on plant growth to save us. Any given plant's growth is constrained by something. Might be sunlight,

Liebig's Law of the Minimum describes why you can't count on plant growth to save us. Any given plant's growth is constrained by something. Might be sunlight, water, phosphorous, nitrogen, or potassium. The last 3 are of course the main ingredients in fertilizers. If a plant needs phosphorous to speed its growth, adding nitrogen won't help. And vise versa. What ever the Liebig Minimum, that's what you have to add to increase the growth, and you have to add enough of it for another factor to become the Liebig minimum. Very few plants out there are CO2-constrained.