The Carbon Cycle
Carbon dioxide has always been a part of our atmosphere, with carbon constantly circulating in a natural cycle between the atmosphere and the plants and animals on Earth. This cycle has been in place for millions of years and does not have any long-term effects on the carbon dioxide levels in the atmosphere.
The carbon cycle is, however, disturbed when humans pull out carbon in the form of fossil fuels such as coal, oil and gas from underground. When we extract energy from fossil fuels through combustion processes, carbon dioxide is emitted as a residue. This means that a carbon source is created. A consequence of such sources emerging has been that the level of carbon dioxide in the air is much higher today than it was three hundred years ago. Unless this trend is reversed, increasing levels of carbon dioxide risk leading to extensive climate changes across the globe.