Some of this sugar is stored, while most of it gets used by the tree for other purposes such as energy and structure. For instance, a great deal of the sugar is linked together to form cellulose, which provides the structure for the tree.

If we look at this sugar from a mass standpoint, we see that a large fraction of it is due to the carbon. Taking into account the other types of molecules that are found in a tree (proteins, lipids, etc.), approximately 45% of the dry mass (not including the water) of a tree comes just from carbon. In other words, a 100 kilogram log of a tree that has been completely dried contains about 45 kilograms of stored carbon.

While each kilogram of dried tree is storing .45 kilograms of carbon, it is removing more than a kilogram of carbon dioxide from the atmosphere. This is because each carbon dioxide molecule contains two oxygen atoms.

This large of an amount gives the idea of using trees to remove carbon from the atmosphere a lot of validity. However, it should also be pointed out that this equation works in reverse. When a tree is burned or allowed to decay completely, the carbon in the tree is put back into the atmosphere as carbon dioxide. Worldwide, we are actually losing forest, and this relationship shows why we should be concerned.

Source: ESA21. Trees and Carbon. Retrieved from http://esa21.kennesaw.edu/activities/trees-carbon/trees-carbon.pdf on October 13, 2010.