A. Are there Agricultural Benefits from Higher CO2?
NASA has observed via satellites that the Earth’s green vegetation has expanded “significantly” since the last 35 years in direct relation to increasing CO2 concentration. Research by 32 authors and 24 institutions in eight countries has shown that 70 percent of the greening was due to increased carbon dioxide fertilization. The remaining 30 percent is driven by nitrogen. However, nitrogen fixation is increased by certain plants known as legumes, which in turn are increased by the carbon dioxide levels. The other major sources of nitrates are lightening and chemical fertilizers. Even climate change advocates acknowledge that a doubling of CO2 since pre-industrial levels boosts the productivity of food crops like wheat, rice, soybeans, etc. by 11.5 percent and more. [Sneed, A (Jan 23, 2018) Ask the Experts: Does Rising CO2 benefit Plants?, Scientific American.]
The United States Department of Agriculture provided data for the US Corn production since 1866. Figure 4 below is a plot of corn production for the years 1970 to 2007 alongside the CO2 concentration for that period. The same kind of plot could be made for each of the various plant related agricultural products.
The upward slope of the corn production is remarkably similar to the slope of the CO2 rise. The R squared for the yearly corn production using a linear line is 79%. This indicates there are numerous significant variables that are not included. Some may include the amount of cloud cover during the growing period, the temperature, the amount of nitrogen based fertilizer, the amount of rain or watering, and other factors. The R squared for the CO2 verses year was a linear line with an accuracy of 99.4%. This indicates that only one or two minor variables are missing.
Based on this curve, the amount of increase in tonnage of corn was 4.91 tonnes/hectare while the CO2 increased 57 ppmv during the same time period or 0.0861tonnes/hectare-ppmv. There are 36.9 million hectare of agricultural land in the world. This means that for every 1 ppmv increase in CO2, the world production would increase sufficiently to feed 3.58 million people for a year. Laboratory experiments have shown that increasing CO2 also reduces the amount of water and nitrogen needed.