The natural carbon cycle

The earth, air and water exchange carbon in a complex, never-ending cycle.

1. Atmosphere:
Carbon typically takes the form of carbon dioxide gas, or CO2, in the earth’s atmosphere.

2. Photosynthesis:
Using a process called photosynthesis, plants on land and in water take CO2 from the atmosphere and use energy from the sun to convert it into carbohydrates and oxygen.

3. Fossil Fuel:
Fossil fuels such as coal, oil and natural gas contain carbon that has been stored in the geosphere for millions of years. By burning those fuels, all sectors of the global economy—industrial, transportation, commercial and residential—release carbon in the form of CO2.

4. Into the Sea:
Rivers carry large amounts of dissolved carbon, created by the erosion of carbon-containing rocks and the decay of plants and animals, into the oceans.

5. Under the Sea:
Ocean currents drive the surface water to great depths and circulate CO2 around the globe. Deep in the ocean, CO2 forms carbonic acid and combines with calcium to create limestone on the ocean floor. Limestone is the largest reservoir of carbon in the carbon cycle.

6. Evaporation:
The oceans represent the largest active pool of carbon near the surface of the earth. The ocean and the atmosphere readily exchange dissolved carbon dioxide in shallow water, where the water is warm or where currents move water upward.

Ed #13 Balance