I get it now PDQ, You think that since CO2 in the atmosphere causes a "greenhouse effect" that it would be like pumping more CO2, into the greenhouse. Two words "closed system." A green house is, from the point of view of individual plants. The whole outdoors is not.

The limitations on plant growth and agriculture OUTDOORS are nutrients and water. I have no doubt that increasing CO2, where water and nutrients are optimized will increase plant production. But assuming that in entire Earth's ecosystem, water and nutrients ARE optimized, it frankly, ignorant and not worthy of a man of your obvious educational attainment.

Here is something to consider. Clearly your interpretation of "the carbon cycle" is not working because the amount of atmospheric CO2 is increasing. If what you are saying was true, wouldn't we have the same amount of atmospheric CO2 and more plants?