Explain The Carbon Cycle
Before we begin to explain the carbon cycle, let us share something about carbon.
Carbon is an element that is found in many things in the air, water and land. It is found in the gases in the air (for example, carbon dioxide), it constitutes a large proportion of living and non-living matter like rocks, plants and animals (including you and I) on land, and it is also dissolved in large quantities in the water and ice in the oceans.
Definition to explain the carbon cycle
It is not hard to explain the carbon cycle. Basically, the carbon cycle depicts the constant flow of carbon between the air, land, sea and living things.
Under natural circumstances, the carbon cycle plays a significant balancing role in maintaining appropriate levels of carbon in the earth's atmosphere, so that there is sufficient level of green house effect to keep the Earth warm and suitable for life, and yet not too heat from the sun becomes trapped by the carbon dioxide in the air that leads to global warming (see definition for global warming).
The following steps explain the carbon cycle – how carbon changes from one form to another as it is repeatedly being exchanged between the atmosphere, land, water and the living beings.
- Absorption of carbon by plants from atmosphere: In the atmosphere, carbon is usually present as carbon dioxide (CO2), one of the important green house gasses. Plants make food through the process of photosynthesis -- they absorb CO2 in the air and in the presence of sunlight and water, produce oxygen and glucose. The glucose produced is stored and used by the plants in growth. Through this process, plants act as a form of carbon storage for the planet, and serve as a means by which carbon is changed into a form that can be used directly by living things.
- Movement of carbon from plants into the animal world: The carbon absorbed by plants is transferred to animals through feeding. As smaller animals get eaten by bigger animals, this carbon is moved up the food chain.
- Movement of carbon from living things to the atmosphere: When plants and animals respire, glucose stored in the plants and animals are broken down to release CO2, water and energy. Through this process, CO2 is released back into the atmosphere.
- Movement of carbon from living things to the land: As plants and animals die and decay or decompose (or when animals defecate and their waste materials decompose), the carbon found in them are released to the environment. When the decaying matter bodies get buried under the ground and are subjected to high pressures and other physical and chemical changes for millions of years, they change into fossil fuels.
- Movement of carbon from fossil fuels to the atmosphere: When the fossil fuels are burnt in power plants, factories, cars and trucks, most of the carbon rapidly enters the atmosphere as carbon dioxide gas. Each year, more than five and a half billion tons of carbon is released by burning fossil fuels. Of the huge amount of carbon that is released from fuels, 3.3 billion tons enters the atmosphere and most of the rest becomes dissolved in sea water.
- Movement of carbon from the atmosphere to the oceans: The oceans, and other water bodies, soak up about a quarter of the carbon dioxide gas from the atmosphere. However, this uptake process is slow. Similarly, under normal conditions, the release of carbon dioxide back into the atmosphere from the ocean is also at a very low rate.
From above points to explain the carbon cycle, it is clear that the total amount of carbon in the environment remains constant. There is no formation or demolition of carbon in this process and it only involves the movement of this element from one form to another.
Through this carbon cycle, the level of carbon in the atmosphere is kept at an optimum level. There is sufficient carbon dioxide in the atmosphere to trap the sun’s heat to keep the Earth’s surface sufficiently warm for living things, yet there is not excessive trapping of heat.
Nature has served the planet well, by maintaining the balance of CO2. Unfortunately, as man increasing learns to make use of “ancient sunlight” (as mentioned by Thom Hartmann, author of the book, The Last Hours of Ancient Sunlight) stored in the form of fossil fuel to drive our industries and economies, at the same time as we cut down our forests on a large scale, we have substantially increased the amount of carbon dioxide in the atmosphere and upset the carbon cycle. CO2 in the atmosphere cannot be taken up by the plants fast enough. They remain in the atmosphere and cause global warming. Read about the consequences of global warming.
Explain the carbon cycle to the people and children around you today, and help spread the message that we need to work on carbon emission reductions.
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