The carbon cycle in depth
Carbon is constantly moved between the air, living things, the oceans and rocks.
In Grade 6 you saw that water and nutrients move in cycles. Carbon does too. Carbon is a key element in every living thing, and it is endlessly recycled around the planet.
Carbon is stored in several places — the air, living things, the oceans, soil and rocks — and processes move it between them:
- Photosynthesis takes carbon dioxide out of the air, locking carbon into plants.
- Respiration in plants and animals returns carbon dioxide to the air.
- Feeding passes carbon from plants into animals.
- Decay of dead matter by decomposers releases carbon back to the air and soil.
- Combustion (burning) of wood and fossil fuels releases stored carbon to the air.
For thousands of years these processes were roughly balanced — about as much carbon went into the air as came out. That balance is the key to the rest of this topic.
- Carbon is stored in the air, living things, oceans, soil and rocks.
- Photosynthesis removes carbon dioxide; respiration returns it.
- Decay and feeding pass carbon between living things and the soil.
- Burning fuels releases stored carbon back into the air.