Carbon Dioxide (CO) is a chemical compound composed of two oxygen atoms bonded to a single carbon atom

It is a gas (at standard temperature & pressure) and exists in the Earth's atmosphere

Carbon Dioxide is currently at a globally averaged concentration of approximately 383 ppm (by volume) in the Earth's atmosphere, although this varies both by location and time

Carbon dioxide is an important greenhouse gas because it transmits visible light but absorbs infrared light

Carbon dioxide is produced by all animals, plants, fungi and microorganisms during respiration and is used by plants during photosynthesis to make sugars which may either be consumed again in respiration or used as the raw material for plant growth

It is, therefore, a major component of the carbon cycle

Carbon dioxide is generated as a byproduct of the combustion of fossil fuels or vegetable matter, among other chemical processes

Inorganic carbon dioxide is generated by volcanoes and other geothermal processes such as hot springs

Carbon dioxide is a solid at temperatures below -78°C

In its solid state, carbon dioxide is commonly called dry ice

It is possible to increase the growth rate of a plant by increasing CO concentrations above standard atmospheric levels, a process called CO enrichment

There are several conditions that must be met for the plants to be able to use the increased CO levels properly

The most important factor is light. Light levels must be very high (more than 20 watts per square foot) or there will be little or no increase in plant growth rates

Plants being enriched with CO will also benefit from slightly higher temperatures than normal (approximately 3 - 5 degrees)

Plants can absorb and process very large amounts of CO

There is usually about 300 to 600 ppm (parts per million) of CO in the atmosphere

Most plants can use up to 1500 ppm of CO (optimum growing conditions)

When using elevated levels of CO research indicates plant growth may increase between 40% - 50%