More Carbon Dioxide is Good for Plants and Agriculture

Skeptics claim that the Carbon Dioxide that is being released by the burning of fossil fuels is actually good for the environment. Their argument is based on the logic that, if plants need CO2 for their growth, then more of it should be better. We should expect our crops to be more abundant and our garden flowers to grow taller and bloom brighter.

However, this “more is better” philosophy is not the way things work in the real world. There is an old, wise saying that goes, “Too much of a good thing can be a bad thing.” For example, if a doctor tells you to take one pill of a certain medicine, taking four is not likely to heal you four times faster or make you four times better. It’s more likely to make you sick.

It is possible to help increase the growth of some plants with extra CO2, under controlled conditions, inside of greenhouses. It is based on this that Skeptics make their claims. However, such claims are simplistic.

Skeptics fail to take into account that a warmer earth will have an increase in deserts and other arid lands which would reduce the land there is available for crops. The corn in Kansas isn’t going to prosper from an increase in CO2. Cactus, though, will be very happy growing where corn used to grow.

Also, because of Global Warming, some areas of the world are receiving intense storms with increased rain. One would think that this should be good for agriculture. Unfortunately, when rain falls down very quickly, it does not have time to soak into the ground. Instead, it builds up above the soil then starts flowing to the lowest level. It then quickly floods into creeks, then rivers, and finally out into the ocean carrying off large amounts of soil and fertilizer.

Yet another problem is that increasing CO2 can harm certain plants. The soybean plants below (Soybean is a major crop in many countries) have grown bigger than ordinary but its defenses against insects are so low that they are heavily damaged.

Enhanced CO2 soybean plant

Figure 1: Plant defenses go down as CO2 levels go up. Soybeans grown at elevated CO2 levels attract many more beetles than plants grown at current atmospheric CO2 levels. Science Daily; March 25, 2008 (Credit: Photo courtesy of Evan Delucia)

Fossil leaf 

Figure 2: More than 55 million years ago, the Earth experienced a rapid jump in global CO2 levels that raised temperatures across the planet. Researchers studying thousands of fossilized plants from that time have found that the rising temperatures may have boosted the foraging of insects. As modern temperatures continue to rise, the researchers believe the planet could see increasing crop damage and forest devastation. Science Daily; Feb. 15, 2008 .

In conclusion, it would be reckless to add CO2 into the atmosphere expecting that it would create wondrous miracles with plant growth. It is only inside of highly controlled areas like greenhouses that it may have a benefit.

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