Definition of Carbon Dioxide

What Is Carbon Dioxide?

Carbon dioxide (CO2) is a chemical compound that is comprised of two oxygen atoms and one carbon atom an exists naturally in our atmosphere at a rate of approximately 0.039%. It is perhaps the most notorious greenhouse gas that is being pumped into the earth’s atmosphere at alarming rates, causing great concern for those in the climate change sciences. Though carbon dioxide transmits visible light it also absorbs strongly infrared and near-infrared light. It therefore has a greenhouse effect on our atmosphere, trapping and holding the sun’s energy in the form of heat; warming the planet on a global scale.

Produced through a wide range of natural processes and human activities, carbon dioxide levels, in the past, have remained at a relatively stable on the earth. The natural processes and activities that add carbon dioxide to the atmosphere include:

  • Changes in orbital cycles
  • Seasonal cycles of carbon dioxide concentrations
  • Respiration of plants, animals, fungi, and other living organisms
  • Volcanic activity
  • Geothermal processes
  • Oceanic processes

But since the industrial revolution, the human-caused carbon dioxide emissions have risen rapidly. Human activities that add carbon dioxide to the atmosphere include:

  • Burning of fossil fuels and biomass
  • Deforestation
  • Raising of livestock for food

Many scientists argue that we need to keep the quantity of carbon dioxide in the atmosphere (in parts per million CO2) below 350 ppm – anything above that will mean widespread, uncontrollable climate change. Prehistoric CO2 levels are estimated to have been around 280 ppm. Unfortunately, the US NOAA reported in October 2010 that the concentration of carbon dioxide in the Earth's atmosphere has already reached 388 ppm.[1]


1. Recent Global CO2. (2010, October). Retrieved October 25, 2010, from NOAA:
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