Ray, I hate to keep calling you out about this statement but it bears repeating that enhanced plant growth is meaningless without improved nutrient production.
Meaningless to AGW alarmists perhaps, but not meaningless to more rational and practical people.
The nutritional value of food is far more influenced by the food processing industry than by modest increases in the levels of CO2 in the atmosphere, and far more influenced by the type of farming techniques used and the soil quality, than by the levels of CO2.
I'll repeat, because you seem to have missed the point, increased levels of atmospheric CO2
increase both the quantity of biomass and the quantity of nutritional elements in the crops.However, the increase in nutritional elements
is not as great as the increase in biomass, unless greater quantities of those nutritional elements are added to the soil in order to reduce the dilution effect.In other words, (in case some readers are having difficulty in grasping the point), if all conditions remain the same, the same amount of water used in the same type of soil with the same amount of artificial fertilizers applied, and the same temperatures and degree of sunlight, and so on, then increased levels of CO2 will tend to increase biomass at a greater rate than the increase in the uptake of nutritional elements. Got it?
We are not animals who can convert cellulose to sugar for further metabolism so if the plant growth is solely biomass it is near worthless to humans.
I wasn't aware that plants can grow without essential nutrients. Are you sure you know what you are talking about, Alan?
From
https://en.wikipedia.org/wiki/Plant_nutrition"There are seventeen most important nutrients for plants. Plants must obtain the following mineral nutrients from their growing medium:-
the macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), carbon (C), oxygen(O), hydrogen (H)
the micronutrients (or trace minerals): iron (Fe), boron (B), chlorine (Cl), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni)"There are other micronutrients which might not be essential for plant growth but are essential for the good health of humans. Selenium is one example. There are many crops that are claimed to be good sources of Selenium, such as Brazil Nuts, Brown Rice, Sunflower Seeds, Mushrooms, Spinach, Oatmeal.
If there is no Selenium in the soil, it will not prevent the above-mentioned plants from growing, so one can't be certain what the levels of selenium might be whenever one buys one of the above foods.
Enhanced CO2 may also lead to increased growth of weeds that compete with food crops for nutrients and may necessitate increased use of herbicides. We know that CO2 is necessary for plant growth but in isolation, the statement that higher levels are good is near worthless.
The are basically two types of plants, C3 and C4. Most food crops are C3. Most weeds are C4. C3 plants respond more to elevated levels of CO2. C4 plants respond less. Therefore, logically, weeds should be less of a problem in elevated levels of CO2, on average. Okay?