The Carbon Cycle

• The movement of carbon between the 4 “spheres” of earth: biosphere, atmosphere, hydrosphere and geosphere

• (“sphere” means “area”)

• The amount of carbon on earth does not change. The carbon just moves from one place to another.

Biosphere

• “Bio” = life

• The area of the earth that contains living organisms (plants and animals).

Atmosphere

• “Atmos” = vapor (gas)

• The area of the earth that is gaseous (made of gas). The air around us.

Hydrosphere

• “Hydro” = water

• The area of the earth that are water:– Oceans– Lakes– Rivers

Geosphere (Lithosphere)

• “Geo” and “lithos” = rock

• The area of the earth that are solid (made of rock)

Where is Carbon in our Environment?

• CO2 in the atmosphere

• CO2 dissolved in water

• Carbonate rocks (example: limestone)

• Deposits of coal, petroleum and natural gas (fossil fuels)

• Living organisms (plants and animals)

• Dead organic matter (found in soil)

** CO2 = Carbon Dioxide

Carbon Sink or Source?

• CARBON SINK = Anything that takes CO2

out of the atmosphere

• CARBON SOURCE = Anything that puts CO2 into the atmosphere

1

4

3

6

5

2

Photosynthesis•(Carbon Sink) Carbon moves from the atmosphere to plants.

Carbon dioxide (CO2) is pulled out of the air and the carbon is used by plants to grow.

“Organic” (Living) Carbon•(Neutral: not a sink or source) Carbon moves from plants to animals.

Carbon in plants moves to animals that eat them.

Animals that eat other animals get carbon from their food, too.

Death and Burial•(Carbon Sink) Carbon moves from plants and animals to the ground

Plants and animals die and decay putting carbon into the ground.

Some get buried very deep and will become fossil fuels in millions and millions of years.

Respiration•(Carbon Source) Carbon moves from living things to the atmosphere.

All living things produce carbon dioxide (CO2).

Animals and plants get rid of carbon dioxide gas through a process called respiration (breathing).

Burning Fossil Fuels•(Carbon Source) Carbon moves from fossil fuels to the atmosphere when they are burned.

When we burn fossil fuels, carbon enters the atmosphere as CO2. Each year, 5.5

billion tons of carbon is released by burning fossil fuels.

(That’s the weight of 100 million elephants!)

Ocean Uptake•(Carbon Sink) Carbon moves from the atmosphere to the oceans.

The oceans soak up (dissolve) some carbon dioxide from the atmosphere.