What is the Carbon Cycle?
The carbon cycle is the means by which carbon atoms are exchanged between living things, the ground, the oceans, and the skies; or biosphere, geosphere, hydrosphere, and atmosphere, respectively. There is about 1,000,000 gigatons of carbon on Earth, most of which is locked in sedimentary rocks and never reaches the surface. At the surface, carbon is continuously engaging in a dynamic exchange of consumption and production. This active exchange is referred to as the carbon cycle. The atmosphere contains approximately 750 gigatons of carbon, mostly in the form of carbon dioxide (CO2). At the consumption end of the carbon cycle, carbon is continuously being drained by 1) the process of photosynthesis, which uses carbon dioxide to create carbohydrates, and 2) the colder parts of the oceans, which are able to absorb carbon dioxide. At the production end of the carbon cycle, atmospheric carbon is continuously being replenished by the following processes: respiration of plants and animals and
The carbon cycle is the process through which carbon is cycled through the air, ground, plants, animals, and fossil fuels. Large amounts of carbon exist in the atmosphere as carbon dioxide (CO2). Carbon dioxide is cycled by green plants during the process known as photosynthesis to make organic molecules (glucose, which is food). This is where the nourishment of every heterotrophic organism comes from. Animals do the opposite of plants–they release carbon dioxide back into the air as a waste product from respiration. (Note: Plants also undergo respiration to make food, but the majority of the carbon dioxide in the air comes from heterotrophic respiration). Decomposers, when they break down dead organic matter, release carbon dioxide into the air also. Decomposers are essential because without them, all of the carbon on the planet would eventually become locked up in dead carcasses and other trash. Decay permits carbon to be released back into the food web. Carbon is also stored in fos
The cycling of carbon from the atmosphere to organic compounds and back again not only involves life but also involves the atmosphere. The carbon cycle describes the pathway that carbon takes as it is transferred from plant to animal to atmosphere to ocean and so on. There is no start or end point, but for purposes of explanation we will start with carbon in the atmosphere. Atmospheric carbon exists mainly as carbon dioxide, but also in the form of carbon monoxide or methane gas. There are also other minor gases in our atmosphere that contain carbon, but we shall lump all these gases together as atmospheric carbon. Back to Global Experts.
Modified with permission from Global Climates – Past, Present, and Future, S. Henderson, S. Holman, and L. Mortensen (Eds.). EPA Report No. EPA/600/R-93/126, U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. pp. 59 – 64. In this exercise, students will explore the carbon cycle and be able to identify carbon sources, sinks, and release agents. Background All living organisms are based on the carbon atom. Unique among the common elements of the earth’s surface, the carbon atom has the ability to form bonds with as many as four other atoms (including other carbon atoms) and to form double bonds to itself. Carbon compounds can be solid, liquid, or gas under conditions commonly found on the earth’s surface. Because of this, carbon can help form solid minerals (such as limestone), ‘squishy’ organisms (such as plants and animals), and can be dissolved in water or carried around the world through the atmosphere as carbon dioxide gas. The attributes of th
• Plants, animals, and soil interact to make up the basic cycles of nature. In the carbon cycle, plants absorb carbon dioxide from the atmosphere and use it, combined with water they get from the soil, to make the substances they need for growth. The process of photosynthesis incorporates the carbon atoms from carbon dioxide into sugars. Animals eat the plants and use the carbon to build their own tissues. Animals return carbon dioxide into the air when they breathe and when they die, since the carbon is returned to the soil during decomposition. The carbon atoms in soil may then be used in a new plant or small microorganisms.
