The Carbon Cycle
Carbon is an important element to living things. As we learned earlier, the most abundant substance in organisms is water. The second most abundant substance is carbon. Much of the solid portions of lifeforms is made up of great amounts of carbon.
How do living things obtain carbon?
Carbon is extracted from the atmosphere by plants through the process known as photosynthesis. This carbon is combined with other elements in complex ways to form organic molecules important to life.
This carbon is later transferred to animals who consume, or eat plants. When plants and animals die, much of their carbon is returned to the atmosphere as the organisms decompose.
Every so often, a plant or animal does not decompose right away. Their bodies are trapped in locations where decomposition can simply not take place. This is most common at the bottom of oceans and seas where the lifeforms become buried by sand.
Instead of returning to the atmosphere, the carbon from these lifeforms is trapped within the Earth. Over millions of years, more and more of the carbon on Earth has been trapped in this manner. Today, almost 99% of all the carbon on Earth has been locked up deep within the Earth.
As rocks weather, this carbon is slowly released back into the atmosphere, creating a balance. For the past several hundred million years, the amount of carbon being locked up in the Earth and the amount being released by weathering rocks was almost perfectly balanced.
This important balance has been altered significantly in the past century as humans have begun using fossil fuels to produce energy. By burning the Earth’s store of carbon, mankind is able to create the energy needed to operate our communities. However, we must be careful as we do so. By releasing more carbon into the atmosphere than is being locked up, we risk causing damage to the delicate carbon cycle.