1. Carbon is absorbed by producers, ie.plants and used in the light independant reaction in photosynthesis.
2. Carbon is then passed onto the consumers in the form of starch and other carbohydrates as the plant is eaten by the producer.
3. All living organisms die. This is where decomposers, ie.bacteria feed on the dead organic matter.
4. Carbon is returned to the atmosphere as all living things, including decomposers respire.
5. Fossil fuels can also be formed if the dead organism does not get decomposed, this is then burnt as fuel releasing the CO2 back into the atmosphere, combustion.