The carbon cycle describes how carbon atoms are recycled through various Earth systems, including the atmosphere, hydrosphere, geosphere, and biosphere. Plants and animals play crucial roles in this cycle through processes such as photosynthesis, respiration, and decomposition, returning carbon to the atmosphere and soil. Human activities, particularly the burning of fossil fuels, have accelerated the release of carbon into the atmosphere, contributing to global warming and an unbalanced carbon cycle.

1. 1.3 THE CARBON CYCLE

2. What Is Carbon?
 An element: 6 protons, 6 neutrons
 The basis of life of earth
 Found in all earth systems

3. Carbon Cycle
 The same carbon atoms are used repeatedly
on earth. They cycle between the atmosphere,
hydrosphere, geosphere and biosphere.

4. Composition of Air
78%
21%
1%
Oxygen
Other
gases
Carbon
dioxide
Water
vapor
Argon
Nitrogen

5. Atmosphere
CO2
(0.035%)
Ar and
other
gases

6. Ar and
other
gases
Atmosphere
CO2
(0.035%)

7. Occurrence of Carbon

8. Occurence of Carbon
Diamond Limestone Coal

9. Nitrogen Cycle Water Cycle
Oxygen Cycle Carbon Cycle
Biogeochemica
l Cycle
Biogeochemical Cycles

10. Utilisation of CO2 Photosynthesis

11. Utilisation of CO2 Photosynthesis

12. Utilisation of Carbon Food Chain
Producers
Primary consumer
(Herbivores)
Secondary consumer
(Carnivores)

13. Utilisation of Carbon Photosynthesis

14. Utilisation of Carbon Photosynthesis

15. Replenishment of Carbon Respiration

16. Replenishment of Carbon Respiration

17. Replenishment of Carbon Combustion

18. Replenishment of Carbon Combustion

19. Replenishment of Carbon Combustion

20. Replenishment of Carbon Combustion
Transportation Industries Thermal Plant

21. Replenishment of Carbon Decomposition

22. Replenishment of Carbon Decomposition

23. Replenishment of Carbon Decomposition

24. Replenishment of Carbon Decomposition

25. Replenishment of Carbon Decomposition

26. Carbon Cycle

27. What Is Carbon?
• Carbon is the chemical backbone
of life on Earth.
• It is found in all living (organic
matter) things on Earth
• It can be found in rocks, oceans,
atmosphere
• Carbon compounds regulate the
Earth’s temperature, make up the
food that sustains us, and provide
energy that fuels our global
economy.

28. The Carbon Cycle
• The same carbon atoms are used repeatedly on earth, cycling
between the earth and the atmosphere.
• Carbon moves from one storage reservoir to another through a
variety of mechanisms.

29. Plants and the Carbon Cycle
• Plants pull carbon dioxide from the atmosphere into
the biosphere, using it to make food through the
process of Photosynthesis.
• The carbon
becomes part of
the plant and is
stored asStarch in
the leaves, stems or
roots of the plant.
• Thus entering the
food chain.

30. Animals and the Carbon Cycle
• When organisms eat plants,
they take in the carbon and
some of it becomes part of
their own bodies.
• All Animals that eat plants
digest the sugar molecules to
get energy for their bodies.
• Respiration, excretion, and
decomposition release the
carbon back into the
atmosphere or soil, continuing
the cycle.
• When humans consume plants
and animals we add to this
cycling of matter.

31. Plants and Animal Life Cycles
•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 (oil, coal, etc.).

32. Carbon and its Return to the Atmosphere
Many natural and industrial activities help
return carbon into the atmosphere.
• Carbon in rocks and underground
deposits is released very slowly into the
atmosphere a process that takes many
years.
• The burning of fossil fuels since the
start of the industrial revolution has
dramatically increased the levels of
Carbon in the atmosphere

33. Natural combustion
 Forest and grass fires are a natural, required
part of the carbon cycle that release carbon
into the atmosphere and geosphere.
 Fire returns carbon to the soil and “cleans out”
unhealthy plants, allowing new plants to grow.

34. The Carbon Cycle

35. Processes that transfer carbon
 Between earth systems
- Photosynthesis
- Respiration
- Consumption
- Decomposition
- Combustion (Burning)
- Weathering (rocks break down and release carbon)
- Dissolve/Vaporize (Between ocean and atmosphere)

36. Carbon in Oceans
 Largest exchange of carbon in carbon
cycle is the dissolving and vaporization
of carbon dioxide between the
atmosphere and ocean surface.

37. Carbon in Our Oceans
Additional carbon is stored in the ocean.
Many animals pull carbon from water to use in
shells, etc.
Animals die and carbon substances are deposite
at the bottom of the ocean.
Oceans contain earth’s largest store of
carbon.

38. Carbon Cycle Diagram
Carbon 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 and
soil
Bodies not
decomposed —
after many
years, become
part of oil or coal
deposits
Fossil fuels are
burned; carbon
is returned to
atmosphere
(Unbalanced)
Carbon slowly
released from
these substances
returns to
atmosphere

39. Balanced Carbon Cycle
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decompressor
are needed to see this picture.

40. Unbalanced Cycle - Human
Impact
 Under balanced conditions, fossil fuels release
carbon stores very slowly into atmosphere.
 When humans burn fossil fuels, it releases a
tremendous amount of carbon into the
atmosphere over a very short time span.
 Increased carbon dioxide in atmosphere
increases global warming
 Fewer plants mean less CO2 removed from
atmosphere

41. Un-balanced Carbon Cycle

42. What is your carbon footprint?
 A carbon footprint is the amount of
carbon emitted into the atmosphere by
your personal, day-to-day activities.
 Examples: Type of car you drive, how far
you drive your car, how much electricity
you use (electricity primarily comes from
burning coal), where the food you buy is
grown and airplane flights.
 Why do we care?? GLOBAL WARMING

43. Things you can do to reduce
your carbon footprint
 Promote plant life, especially trees
 Buy a fuel efficient vehicle
 Purchase locally grown food
 Reduce electricity use
 Reduce how far/much you drive
 Take less airplane trips
 Reduce, Reuse, Recycle!

44. CFA
1. Why is the carbon in the atmosphere
increasing?
2. Of the seven processes that transfer
carbon, what is the only one that reduces
the carbon in the atmosphere?
3. Why are we worried about the amount
of carbon in the atmosphere?