CARBON dioxide is not an air pollutant. It is plant food. All life on Earth depends on it. It is natural. It forms the bubbles in bread, champagne, and Coca-Cola. You breathe it out, and plants breathe it in.
The Earth contains a lot of CO2, but the atmosphere contains so little that the United Nations’ Intergovernmental Panel on Climate Change (IPCC) rightly calls CO2 a “trace gas”. A scientific mystery is why the air does not hold more CO2 than it does. Half a billion years ago, there was almost 20 times today’s CO2 concentration.
Most farmers would prefer to grow crops under much-higher concentrations of CO2 than today’s 385 parts per million—less than 1/25 of 1 percent of the atmosphere. To feed the world, low CO2 concentration is not such a great idea. High concentrations are better, and they cause no harm. Experiments have shown that even delicate plants such as orchids thrive at CO2 concentrations of 10,000 ppm.
That is why U.S. Supreme Court Justice Anthony Scalia has declared that if CO2 is to be labeled an “air pollutant”, then so must Frisbees and flatulence.
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.