Climate Change, Effect of Carbon Dioxide

 

Climate Change, Scientific Considerations: CO2

Much of the discussion about the effects of green vegetation centers on the advantageous effects of trees because they provide shade and they “sequester carbon” by absorbing CO2, which is deemed to be a greenhouse gas. This line of thinking leads to the logical conclusion that the ideal goal is an atmosphere entirely devoid of CO2. Actually, if that goal were achieved we would all die. And anyone who passed his high school course in biology should know that. Green plants cannot exist without the CO2 that is emitted by animals, and we cannot breathe without the O2 that is emitted by the plants. Furthermore the food that we eat ultimately derives from vegetation. Even if we don't eat the plants themselves, we eat the herbivores that eat the plants, or the carnivores that eat the herbivores that eat the plants, or the carnivores that eat the carnivores that eat. . . etc.

However, at present (2019) it appears that world governments are preparing to spend billions, possibly trillions, of dollars in an attempt to achieve two mutually exclusive results: increase vegetation while decreasing CO2. The truth is that CO2 promotes plant growth. For any individual plant one would expect that the greater the area of leaf exposure to the sunlight the greater the amount of solar energy the plant will absorb. Therefore, in general, larger plants should absorb more radiated energy than small ones. The point of overriding importance is that relatively small variations in the concentration of CO2 affect the plant growth significantly. Extensive experimental data demonstrates that even small increases in CO2 have a large effect on plant growth, as shown here, for example: http://www.science.poorter.eu/1993_poorter_vegetatio.pdf, and: http://www.co2science.org/data/plant_growth/plantgrowth.php

Thus, any excess of CO2 in the atmosphere tends to be self-correcting: when there is an excess the plants grow faster, and thereby absorb more CO2.

The cooling effect of vegetation has been verified by controlled experiments as reported, for example, here: http://nargeo.geo.uni.lodz.pl/~icuc5/text/O_26_4.pdf

Some of the climate change literature displays a misunderstanding that plants either reflect sunlight or absorb it only to convert that energy into heat energy. But that is not what happens. The absorbed energy is converted into chemical energy through the process of photosynthesis. Some estimate of the degree of energy absorption by plants can be had by noting the amount of chemical energy produced from sunlight by green grass, which we often don’t consider as having any significant nutritional value, because we, as humans can't digest it – but herbivorous animals can. A good milk cow produces as much as 6-10 gallons of milk daily (at 2400 kcal./gallon). That is a tremendous amount of chemical energy, just from one day’s grass consumption. Trees and bushes also cool the atmosphere by photosynthesis, besides having the additional cooling benefit of providing shade. And they provide food for sheep, goats, deer, horses, camels, certain fish, etc.

Taller plants also provide an additional cooling effect by shading surfaces like concrete, asphalt, and brick, that would otherwise absorb and re-radiate solar energy, especially at night when the sky is cooler than the earthbound surfaces. There is also the consideration of the energy absorbed by the plants that is not transferred to animals; i.e. uneaten leaves. They decompose, but much of this exothermic process takes place during the fall and winter when the extra heat becomes an advantage.

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