Why is the circulation of carbon in nature important?

Why is the circulation of carbon in nature important?
Answer:
The carbon in the form of food travels to animals from plants through food chains. In atmosphere the concentration of carbon dioxide is very low— only about 0.03% to 0.04%. Therefore, if carbon dioxide is not circulated back to our nutrient pool, there will be shortage of C02 and plants will not be able to carry out photosynthesis and the whole cycle will be disrupted. Combustion of fuel also adds carbon dioxide in the atmosphere. Carbon thus cycles through physical and biological activities.