The different forms and compounds in which carbon atoms are found are considered chemical reservoirs of carbon. These reservoirs include atmospheric carbon dioxide, calcium carbonate (in limestone), natural gas, and organic molecules, to name a few.

: Plants use carbon dioxide and energy from the sun to form carbohydrates in photosynthesis. The carbohydrates are consumed by other organisms, and are eventually broken down, or “oxidized”.

: The process of respiration. The chemical representation of how carbohydrates are broken down, or oxidized, thereby releasing energy for use by the consuming organisms. The carbon used and circulated in photosynthesis represents only a tiny portion of the available global carbon.

Atmospheric carbon dioxide levels have increased by 30% since the 1800’s (industrial revolution).This increase can be explained, primarily, but several human activities. The most significant of these activities is the burning of fossil fuels.