1. Global Carbon Cycle
7. b. Students know the global carbon cycle: the different physical and chemical forms of carbon in the atmosphere, oceans, biomass, fossil fuels, and the movement of carbon among these reservoirs.

2. The Global Carbon Cycle
Carbon dioxide in the atmosphere is dissolved and stored in the ocean as carbonate and bicarbonate ions, which organisms take in to make their shells.

3. When these organisms die, their shells rain down to the ocean floor, where they may be dissolved if the water is not saturated in carbonate. Otherwise, the shells are deposited on the ocean floor and become incorporated into the sediment, eventually turning into a bed of carbonate rock, such as limestone.

4. Carbon Reservoirs
Carbon is held temporarily in a number of reservoirs, such as in
biomass (carbon in living things)
the atmosphere (as carbon dioxide)
oceans
fossil fuels

5. Carbon Reservoirs Carbon dioxide
Atmosphere
Biosphere
Oceans
Fossil Fuels
Carbon dioxide
Sugar and organic molecules in living organisms
Dissolved carbon dioxide and bicarbonate and carbonate ions
Coal
Oil
Gas Deposits

6. How is carbon cycled through?
Biological Means
Respiration and photosynthesis
Physical Means
Plate tectonics
Geologic Cycle

7. Movement of the carbon cycle
Some movement of carbon between reservoirs takes place through biological means
respiration
photosynthesis

8. Movement of Carbon Cycle
Physical means, such as those related to plate tectonics and the geologic cycle.

10. The Atmosphere and Ecosystems
Acid Rain Acid rain, which is caused by airborne pollutants that lower the pH of rain, has damaged many forests and lakes, especially in the Northeast. 3

11. Section 1
Global Temperature
The Greenhouse Effect The greenhouse effect occurs when greenhouse gases, such as carbon dioxide, trap heat within Earth's atmosphere. 5