[PeterPrinciple]

Happer explained, among other points, that most plants were actually designed to exist in an atmosphere much richer in CO2, which he described as a wonderful and beneficial molecule. Almost all plant life would benefit from more CO2, which is why farmers pump it into their greenhouses, Happer explained.  

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Learned that in college. Plants are c02 starved. It is a limiting growth factor. There are two chemical paths in a plant to capture the sunlight. One is relatively efficient, the other requires much more energy to capture the CO2 and is used most of the time.

Injecting CO2 in a green house is used to stimulate growth of high value crops.

Finally some common sense. But I explained this to a “smart” graduate student once and the response? “See, that proves my point, I wouldn’t want to walk in that greenhouse.” I shook my head and walked away. CO2 is such a small percentage of the atmosphere..................

[central_va]

At the current level of 400ppm we are at an historical low point in CO₂ levels. During the Jurassic Period (200 mya), average CO₂ concentrations were about 1800 ppm or about 4.7 times higher than today.