By Melanie Friedel, American Forests
Look at all that carbon sinking! Credit: Max Pixel
Don’t be fooled by the name; a carbon sink is not where we go to wash carbon. Actually, it’s something found in nature that holds or stores carbon — technically anything that absorbs more carbon that it releases.
Forests are great examples. In fact, U.S. forests alone store 14 percent of all annual carbon dioxide (CO2) emissions from the national economy. But how does it happen? You may know that trees survive by performing a process called photosynthesis, in which the tree actually consumes CO2. Being absorbed by trees is just one way that carbon moves through forests as part of the carbon cycle. This cycle is the process by which carbon travels from the atmosphere into the Earth and its organisms, and then travels back into the atmosphere.
During photosynthesis, trees and plants “sequester,” or absorb, carbon from the atmosphere in the form of CO2, using it as food. The chemical equation for photosynthesis is: 6 CO2 (the carbon they take in) + 6 H2O (the water they absorb) + sunlight = C6H12O6 (a sugar called glucose) + 6 O2 (the oxygen they release). The carbon from the CO2 becomes part of the plant and is stored as wood. Eventually, when the plant or tree dies, the carbon it has been storing is released into the atmosphere. This, however, is not the only route carbon can take back into the atmosphere.
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