THE CARBON CYCLE

What Is Carbon?An element

The basis of life on earth

Present in rocks, oceans and atmosphere

Carbon CycleCarbon is cycled between the earth and the

atmosphere

Plants Use Carbon DioxidePlants pull carbon dioxide (CO2) from the

atmosphere and use it to make food

The carbon becomes part of the plant (stored food)

Animals Eat PlantsWhen organisms consume plants, they take in

the carbon and some of it becomes part of their own bodies.

Decomposition of Plants and Animals

When plants and animals die, most of their bodies are decomposed and carbon atoms are returned to the atmosphere.

Some are not decomposed fully and end up in deposits underground as fossil fuels (oil, coal, etc.).

Carbon Slowly Returns to Atmosphere

Carbon found in rocks and underground deposits is released very slowly into the atmosphere

The result is that carbon on earth is found in some active pools and some relatively inactive pools, depending on the rate at which it cycles in and out.

Carbon Cycle DiagramCarbon in Atmosphere

Plants use carbon to make food

Animals eat plants and

take in carbon

Plants and animals die

Decomposers break down dead things,

releasing carbon to

atmosphere andsoil

Bodies not decomposed —

after many years, become part of oil or coal deposits

Fossil fuels are burned; carbon is

returned to atmosphere

Carbon slowly released from

these substances returns to

atmosphereActive compartments are denoted in red

Carbon in OceansCarbon is also stored in the ocean.

Carbon is found in the form of calcium carbonate in the shell of aquatic species.

When animals die, carbon substances are deposited at the bottom of oceans.

Oceans contain earth’s largest reservoir of carbon.

The Carbon Cycle

Human ImpactThe release of carbon in fossil fuels is very slow

Burning releases additional carbon into atmosphere — especially fossil fuels

Increased carbon dioxide in atmosphere increases global warming

Fewer plants mean less CO2 removed from atmosphere