THE CARBON CYCLE
TEK: Diagram abiotic cycles, including
the carbon, nitrogen and rock cycles.

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

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

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)

Plants consume and release
Carbon Dioxide
 Plants pull carbon from the atmosphere
or hydrosphere and use it to make food –
— photosynthesis.
 Plants release carbon by respiration.

Animals consume and release
carbon
 When organisms eat (consume) plants
or other organisms, they take in the
carbon and some of it becomes part of
their own bodies.
 When they breath (respiration) they
release carbon.

Plants and Animal Die
 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
geosphere deposits underground (soil, oil,
coal, etc.) or at the bottom of ocean.

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.

Carbon Slowly Returns to Atmosphere
 Carbon in rocks and underground
deposits is released very slowly into the
atmosphere.
 This process takes many years and is
usually caused by weathering.

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

Oceans store carbon on
ocean floor.
Many animals pull carbon from water to
use in shells, etc. When these animals
die, the carbon substances are
deposited at the bottom of the ocean.

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

Balanced Carbon Cycle
QuickTime™ and a
decompressor
are needed to see this picture.

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

Un-balanced Carbon Cycle

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

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!

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?