http://www.laconiadailysun.com/opinion/letters/87519-james-veverka-7-21-380
To the Daily Sun,
One of the most popular claims of climate change deniers is "CO2 is plant food". Attached to this will always be claims about how greenhouses grow bigger plants so more CO2 must be good for humans. This is an argument from ignorance (or deceit) because bigger plants isn't all you get. Worldwide field studies and controlled climate experiments have turned up some compelling data that can't be ignored. High levels of CO2 create hollow plants.[1] By hollow I mean the extra growth is in sugars and starches but there is a significant loss in the content of proteins and important minerals such as Iron and Zinc. Almost 3 Billion people rely on a variety of crops for their nutrition and some of these such as Wheat are hit by significant losses in vital nutrients. Studies have even shown that our present crops have less nutrition than crops grown in pre-industrial times. According to the NIH, "Iron deficiency ranked ninth among 26 risk factors included in the global burden of disease study, and accounted for 841,000 deaths and 35,057,000 disability adjusted life years lost. Large sections of populations in Africa and Asia are at risk of dietary zinc deficiency and resulting high rates of stunting."[2] Since 2 billion people are deficient in zinc and 1 billion have iron-deficiency anemia, why on Earth would anyone favor hollow food with less Iron and Zinc?[3]
On top of this is the problem of soil moisture evaporation which will increase in a warmer world. Drier soil due to higher evaporation rates will also create growing problems. While growing may improve in far northern latitudes, heat related soil evaporation will not only stress plants but whatever you get will have less nutritional value. High levels of CO2 also favors weeds over crops and trees.
Another growing problem presently is the increased range of insect pests and plant diseases. Warming has already caused important changes in species diversity and distribution.[4] One example is the destruction wrought on forests in North America by the Pine Bore Beetle which has significantly extended its range northward in the last century. With a changed environment, natural selection may also favor bigger more voracious insects. Insect borne diseases such as Malaria and Dengue are also likely to increase.
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