It was noted in previous posts that for crops with C3 photosynthetic pathway the current levels of atmospheric carbon dioxide are limiting to plant growth. Crops are currently starved of CO2 in a similar way to being starved of water, nitrogen, phosphorus, light etc. Current atmospheric levels of CO2 can thus be regarded as a plant stress, which weakens them and makes them inefficient. At higher levels of CO2 this stress is reduced, and the plant copes better with all other types of stress, including heat and cold, atmospheric pollution, root pathogens, as well as shortages of water, minerals etc.
Sylvan Wittwer (Professor emeritus at Michigan State University, who directed the Michigan Agricultural Experiment Station for 20 years and chaired the Board on Agriculture of the National Research Council) has remarked:
There has been and still remains, a great reluctance on the part of many climatologists and ecologists, and especially environmentalists, to accept the concept that the rising level of atmospheric CO2 could be more beneficial than harmful for plant growth, food production, and the overall biosphere…Yet the scientific evidence is overwhelming.
Summary data from 279 published studies is shown below in which plants of all types were grown under paired stress (red) and unstressed (blue) conditions. For resource-limited plants the benefits of increased CO2 are astounding.
Wittwer points out that of the hundreds of scientific reports documenting the benefits, Al Gore carefully selected five reports and a personal communication to emphasize possible negative aspects to enhanced CO2 on plants. Gore knew what he was doing, of course – he either deliberately rejected the facts, or gave instructions to researchers for his book only to cherry pick papers that support his alarmist agenda. Again we see him as a lying propagandist.