Carbon Cycle

Carbon is present in all living things, carbon dioxide in the atmosphere and dissolved in water, fossil fuels (coal, oil and gas) and dead organic matter (e.g. soil humus). Through the natural course of life and death this carbon moves through the environment in a process known as the carbon cycle.

The foundation of the carbon cycle lies with plants. During photosynthesis, a plant absorbs carbon dioxide (one carbon atom and two oxygen atoms) from the atmosphere. Carbon is used to form the organic body of the plant, while oxygen is released back into the atmosphere. Later, when the plant respires, decays or is burned, carbon is returned to the environment. In addition, it can be absorbed into the body of animals feeding upon the plant, whereupon the carbon will be passed up the length of the food chain, being released during respiration, and when the top predator dies.

Naturally, the carbon cycle circulates relatively quickly and released carbon is easily reabsorbed by the earth’s environment, leaving the process in a state of equilibrium. However, burning of fossil fuels unbalances this.

Fossil fuels are formed from animals and plants that died millions of years ago. When they are extracted and burned they release carbon atoms that were absorbed in ancient times, adding volumes of carbon that would not naturally be present in the atmosphere today. The environment is unable to absorb this excess carbon, which consequently builds up, contributing to climate change.

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