What is CO2 Gas?

By Lexa W. Lee; Updated April 24, 2017

CO2 or carbon dioxide is a colorless gas consisting of carbon and oxygen. It occurs naturally in the atmosphere. Plants use it and animals produce it in respiration. It is also a major greenhouse gas emitted by fossil fuel combustion, according to the Environmental Protection Agency (EPA).

The Carbon Cycle

The term carbon cycle refers to the natural exchange of carbon dioxide gas in the environment, consisting of a number of processes. Plants remove it from the atmosphere by using it, along with water and sunlight, to photosynthesize their food. Humans and animals exhale CO2 as a waste product. It is both absorbed and released at the ocean surface, and a relatively small amount is released in volcanic eruptions.

Fossil Fuel Combustion

Burning fossil fuels like oil, coal, and gas emits large quantities of CO2 gas into the atmosphere, according to the EPA. Cars, power plants, and industry around the world produce large amounts of CO2 and other gases, which are referred to as greenhouse gases, because they contribute to the gradual warming of the atmosphere.

Other Emissions

The manufacture of certain products like ammonia, steel and cement release CO2 gas. Also, the breakdown or evaporation of plastics, lubricants, solvents release CO2, according to the EPA.

About the Author

Lexa W. Lee is a New Orleans-based writer with more than 20 years of experience. She has contributed to "Central Nervous System News" and the "Journal of Naturopathic Medicine," as well as several online publications. Lee holds a Bachelor of Science in biology from Reed College, a naturopathic medical degree from the National College of Naturopathic Medicine and served as a postdoctoral researcher in immunology.