This consequence has long been recognized by agricultural scientists. As early as 1979, for example, Gifford suggested that a significant part of the upward trend of Australia's wheat yields over the period 1958-1977 "may be due to atmospheric [CO2] change rather than to managerial or genetic causes." Three years later, Wittwer (1982) noted that "the 'green revolution' has coincided with the period of recorded rapid increase in concentration of atmospheric carbon dioxide, and it seems likely that some credit for the improved yields should be laid at the door of the CO2 buildup." Based on the voluminous data summarized by Idso and Idso (2000) for the world's major food crops, for example, it can be calculated that the past 150-year increase in atmospheric CO2 concentration has resulted in mean yield increases of 70% for C3 cereals, 28% for C4 cereals, 33% for fruits and melons, 62% for legumes, 67% for root and tuber crops, and 51% for vegetables. What is more, the future benefits of atmospheric CO2 enrichment on agriculture look brighter still, as evidenced by the mean percentage yield increases listed in the Table below for an additional 300 ppm rise in CO2.
Similar sentiments have been expresses by other scientists, as they look forward to the future with great anticipation of the CO2-induced benefits likely to accrue to agriculture. Still others cannot wait for the future. Today in Holland, for example, growers produce crops, vegetables and ornamentals in glass greenhouses with air enriched to as much as 1,000 ppm CO2 during daylight hours, experiencing yield enhancements on the order of 20 to 40% for this multi-billion dollar industry.
Wittwer (1995) sums up the CO2-induced benefits to agriculture thusly:
"The rising level of atmospheric CO2 could be the one global natural resource that is progressively increasing food production and total biological output, in a world of otherwise diminishing natural resources of land, water, energy, minerals, and fertilizer. It is a means of inadvertently increasing the productivity of farming systems and other photosynthetically active ecosystems. The effects know no boundaries and both developing and developed countries are, and will be, sharing equally."
Gifford, R.M. 1979. Growth and yield of CO2-enriched wheat under water-limited conditions. Australian Journal of Plant Physiology 6: 367-378.
Idso, C.D. and Idso, K.E. 2000. Forecasting world food supplies: The impact of the rising atmospheric CO2 concentration. Technology 7S: 33-55.
Wittwer, S.H. 1982. Carbon dioxide and crop productivity. New Scientist 95: 233-234.
Wittwer, S.H. 1995. Food, climate, and carbon dioxide: The global environment and world food production. Lewis publishers, Boca Raton.