Fast Carbon Cycle

The fast carbon cycle operates on a daily basis as living things breathe and digest food and influencing changes to carbon stores over decades and centuries.

Key processes in the fast carbon cycle

The key processes in the fast carbon cycle include:

• Photosynthesis: the absorption of CO₂ from the atmosphere (terrestrial plants) and from oceans (marine plants) to produce organic carbon structures.
• Respiration: the release of CO2 into the atmosphere, soil and oceans by animals as they exhale.
• Digestion: the release of carbon compounds by terrestrial and marine animals after feeding on carbon-rich material.
• Decomposition: the breakdown of animals and plant structures by bacteria and the release of carbon compounds into the atmosphere, soil and to the ocean floor. Where oxygen is present it releases CO₂, where it is absent CH₄ is released.
• Combustion: natural fires release carbon compounds from vegetation to the atmosphere

All these involve living (organic) processes in some way.

Additionally, there is an on-going transfer of CO₂ that is non-organic:

• Ocean-atmosphere exchange: there is a mutual transfer of CO₂ between the lower atmosphere and ocean surfaces. The flow can go in either direction depending on the balance of CO₂ between the two stores, temperature and conditions of air and water, but the prevailing direction is from the atmosphere to the ocean.