Carbon exists in the atmosphere primarily as the gas carbon dioxide. Carbon dioxide is essential to photosynthesis in plants and is also a prominent greenhouse gas. It is an important component of Earth's atmosphere because it absorbs and emits infrared radiation, thereby playing a role in the greenhouse effect.
Carbon emissions stem from all sources of fossil fuel burning, and the concentration of carbon dioxide in the atmosphere has increased by about 30% because of changes in human activity and practical use over the last 200 years.
Greenhouse gases are essential to maintaining the current temperature of the Earth, and it is important to be knowledgeable of their properties and their effects on the atmosphere.