Carbon Dioxide

CARBON DIOXIDE IS a naturally occurring gas. Chemically, it is stated as CO2, which means that each carbon dioxide molecule has two oxygen atoms bonded to a single carbon atom. CO2 has many practical applications. CO2 measurements are now being used as a way to test the cardiovascular system. This new tool has the promise of not being as invasive as other diagnostic methods. CO2 can be frozen into dry ice, and has numerous chemical uses. It is often a byproduct from chemical reactions. It has a number of common uses, such as providing the fizz in soft drinks.

Humans and other animals also expel CO2 when they exhale. In the respiratory processes of humans, mammals, birds, reptiles, and fish, oxygen is breathed into the lungs and CO2 is exhaled. Their breath contributes to the CO2 cycle. In the CO2 cycle, plants take in CO2 and in the photosynthesis process make chlorophyll and oxygen from the CO2 as it combines with water, minerals, and other products in the plant's chemistry.

Plants are able to store huge quantities of carbon in hydrocarbon compounds. CO2 plays a vital role in plant growth. There are also tremendous quantities of CO2 locked in fossilized hydrocarbons, such as coal and oil. In addition, peat bogs and the plant material frozen in the Arctic tundra are repositories of vast quantities of organic material and, thus, of carbon and CO2.

The Earth's atmosphere is composed of a number of gases, including: nitrogen, oxygen, CO2, water vapor, argon (an inert gas), methane, varying amounts of ozone, and other gases such as nitrous oxide. The greenhouse effect is a natural phenomenon that is caused by these gases. Without the greenhouse effect, the biosphere of Earth would either never have existed, or it would die because the Earth's climate would be too cold. CO2 and other gases such as methane, ozone, and others act as a thin blanket that retains heat that would otherwise be radiated out into space. Instead, these gases capture some of the long-wave infrared radiation and return it to the Earth's surface.

Sunlight enters the Earth's atmosphere as white light of all wavelengths, from ultraviolet to infrared waves. Some wavelengths of energy, such as gamma rays and x-rays, are adsorbed or reflected in the upper levels of the atmosphere and do not affect the surface of the Earth. Most of the sunshine that strikes the surface of the Earth is white light sunshine. It is in the visible light spectrum, which is seen by human eyes, and ranges from purple to red in a spectrum of increasing wavelengths. Just beyond the visible red spectrum is infrared radiation. About 60 percent of the sun's radiation is infrared, which is radiation invisible to humans and most animals. The tongues of snakes have infrared sensors to detect the heat of animals in the dark. Camera film can be designed to detect infrared radiation, making it visible to humans. [Page 164]

Carbon dioxide and other gases, such as methane and ozone, act as a thin blanket that retains heat that would otherwise be radiated out into space. Without this natural greenhouse effect, Earth's climate would be too cold for much life.

...