The Carbon Cycle

• The carbon cycle is a complex process that describes the flow of carbon, a crucial life-sustaining element, through Earth’s lithosphere (land), hydrosphere (water), and atmosphere (air).
• Carbon is present in the atmosphere as carbon dioxide (CO2). This gas is taken up by plants in the process of photosynthesis to produce glucose for energy and growth.
• During photosynthesis, plants convert carbon dioxide and water into glucose (a source of energy) and oxygen (a byproduct).
• Animals, including humans, consume plants (and other animals) as part of their diet, thus taking in carbon which has been converted into complex molecules by the plants.
• Besides consuming carbon, all living organisms also emit carbon dioxide back into the atmosphere through respiration. This process involves the breakdown of glucose, which releases energy for bodily functions and produces carbon dioxide as a waste product.
• Dead plants and animals, over millions of years, turn into fossil fuels (such as oil, coal, natural gas) under high pressure and heat. This process stores carbon underground.
• When fossil fuels are burnt for energy (in factories, vehicles, power plants, etc.), a process called combustion, carbon stored for millions of years is released back into the atmosphere as carbon dioxide.
• Decomposers, like fungi and bacteria, break down dead organisms and waste products. During decomposition, these organisms return carbon back to the environment as carbon dioxide.
• Some carbon is also sequestered or stored in long-term stores like peat bogs and as calcium carbonate in marine organisms’ shells. This process aids in removing carbon from the atmosphere.
• Human activities are greatly influencing the carbon cycle. Deforestation and burning of fossil fuels are increasing the carbon dioxide levels in the atmosphere, thus contributing to global warming and climate change.
• Understanding the carbon cycle is essential to predicting and managing the impacts of climate change, as it allows us to see how humans affect natural processes.
• Key term: Carbon Sequestration - the process by which carbon dioxide is captured from the atmosphere and stored long-term in plants, soil and water.
• Key term: Combustion - the chemical process of burning, which combines a substance with oxygen to produce heat and carbon dioxide.