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Hot air, greenhouse gases and plant productivity

POSTED: November 4, 2009 12:42 p.m.
Washington is debating how tough legislation should be to reduce carbon emissions and slow global warming. Doomsayers are predicting the 21st-century rise in carbon dioxide will bring heating of the earth, flooding of coastal cities, increases in hurricane strength and frequency, proliferation of tropical diseases, extinction of species and more.
Yet the pessimistic prophets dare not weaken their revelations with one certainty: Rising CO2 will make fields and forests more productive.
CO2 really is a “greenhouse gas.” It is used in greenhouses to make plants grow better. Biology students learn early that CO2 and water combine in photosynthesis to produce organic compounds and make plants grow. Higher CO2 levels stimulate photosynthesis and plant growth. In, “How a Greenhouse Works,” Julia Mahler writes: “CO2 is essential to photosynthesis and thus it must be present in the air at least in at least 300 ppm in order for plants to grow properly. When CO2 is deficient in the air plants simply do not grow, their growth is very slow and stunted. It is also actually possible to speed plant growth up by increasing CO2 levels in the air. The simple addition of CO2 to the air is as good as adding fertilizer to your plants.”
It is a cruel irony that the best documented effect of rising CO2 is lost in the “climate change” debate. Monumental good news is hidden under an avalanche of semi-documented gloom. Any other change that promised increases in plant growth and food production would be considered a miracle.
Government agencies who warn about global warming acknowledge the benefit. An assessment from the U.S. Global Change Research Information Office said in 2000, “Within the next 50 years, forest productivity is likely to increase with the fertilizing effect of atmospheric carbon dioxide.” Hundreds of actual experiments in field and greenhouses show that growth and yield will increase by 25-50 percent if CO2 rises to double the present levels.
Even well-fed Americans can see the benefit of producing food on 25-50 percent less land compared to what would be needed at today’s CO2 level. That excess farmland could revert to precious habitat for the thousands (some say millions) of species that are supposed to go extinct.
Regardless of attempts by the EPA to declare CO2 an air pollutant, it is an absolute requirement for plant life and thus for every creature that eats plants or animals. Imagine the clamor if CO2 was at 19th-century levels and decreasing. .
Horticulturists know the benefit. The Ontario (Canada) Ministry of Agriculture, Food and Rural Affairs recommends 1,000 ppm CO2 (as opposed to about 380 ppm outside) during daytime when a greenhouse is closed, and says “Increased CO2 levels will shorten the growing period (5-10 percent), improve crop quality and yield, as well as increase leaf size and leaf thickness.”
Not only does rising CO2 increase plant growth, it increases the efficient use of water. The stimulation of plant growth by CO2 was twice as large in drought as with sufficient water.
Humans sometimes manage the earth poorly because they lack knowledge of the countless effects and interactions; many simple systems we claim to know well are managed poorly. The Katrina tragedy fell under this category; it was not a result of global warming.
Biosphere II, the three-acre experimental glasshouse in the Arizona desert publicized in the ’90s was a giant white elephant that some called an experiment. The New York Times reported its failure; “The would-be Eden became a nightmare. ... Not only did oxygen levels plummet from 21 percent to 14 percent, barely sufficient to keep the Biospherians alive, but carbon dioxide skyrocketed ... .” Plants no doubt grew faster there than in their natural habitat, because CO2 inside averaged about 1,000 ppm in summer and up to 4,000-4,500 ppm in winter.
Management complexity of Biosphere II pales beside the grand experiment now under way to cool the earth. Undeterred, the bold Earth prophets propose a cap-and-trade program that taxes the assumed detrimental effects of rising CO2, while ignoring proven benefits.
The proposed carbon tax is unique; it taxes a free and productive natural resource to solve a distant and doubtful problem. It is like taxing the worship of God to insure the final result.

A University of Georgia professor emeritus, Brown is an adjunct scholar with the Georgia Public Policy Foundation and author of “The Greening of Georgia: The Improvement of the Environment in the Twentieth Century.”
 

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