Carbon Cycle

Carbon Cycle

Carbon is essential to all life as it is the main constituent of living organisms. It serves as the backbone component for all organic polymers, including carbohydrates, proteins, and lipids. Carbon compounds, such as carbon dioxide (CO₂) and methane (CH₄), circulate in the atmosphere and influence global climates.

Carbon is circulated between living and nonliving components of the ecosystem primarily through the processes of photosynthesis and respiration. Plants and other photosynthetic organisms obtain CO₂ from their environment and use it to build biological materials. Plants, animals, and decomposers (bacteria and fungi) return CO₂ to the atmosphere through respiration. The movement of carbon through biotic components of the environment is known as the fast carbon cycle. It takes considerably less time for carbon to move through the biotic elements of the cycle than it takes for it to move through the abiotic elements. It can take as long as 200 million years for carbon to move through abiotic elements such as rocks, soil, and oceans. Thus, this circulation of carbon is known as the slow carbon cycle.

Carbon cycles through the environment as follows:

• CO₂ is removed from the atmosphere by photosynthetic organisms (plants, cyanobacteria, etc.) and used to generate organic molecules and build biological mass.
• Animals consume the photosynthetic organisms and acquire the carbon stored within the producers.
• CO₂ is returned to the atmosphere via respiration in all living organisms.
• Decomposers break down dead and decaying organic matter and release CO₂.
• Some CO₂ is returned to the atmosphere via the burning of organic matter (forest fires).
• CO₂ trapped in rock or fossil fuels can be returned to the atmosphere via erosion, volcanic eruptions, or fossil fuel combustion.