NOTES 20

1
NOTES 20 The Carbon Cycle, The Greenhouse
Effect, and Global Warming
2
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere
3
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere
4
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere
5
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere
6
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere
7
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere
8
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Respiration in the mitochondria of plant and
   animal cells produces CO2 waste, which is
   released into the atmosphere

9
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Photosynthesis in plants (land) and algae (water)
   remove CO2 from the atmosphere to make glucose
   during photosynthesis

10
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

• Photosynthesis in plants (land) and algae (water)
  remove CO2 from the atmosphere to make glucose
  during photosynthesis

11
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Photosynthesis in plants (land) and algae (water)
   remove CO2 from the atmosphere to make glucose
   during photosynthesis

12
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Photosynthesis in plants (land) and algae (water)
   remove CO2 from the atmosphere to make glucose
   during photosynthesis

13
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Photosynthesis in plants (land) and algae (water)
   remove CO2 from the atmosphere to make glucose
   during photosynthesis

14
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Combustion (burning) of wood, coal, oil, and
   natural gas add extra CO2 to the atmosphere

15
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Combustion (burning) of wood, coal, oil, and
   natural gas add extra CO2 to the atmosphere

16
The carbon cycle continuously moves carbon
dioxide (CO2) into and out of the Earths
atmosphere

1. Combustion (burning) of wood, coal, oil, and
   natural gas add extra CO2 to the atmosphere

17
Natural CO2 Cycle Disrupted

• On a global scale, the amount of CO2 put into the
  atmosphere by respiration is equal to the amount
  of CO2 removed by photosynthesis.
• Humans have changed the carbon cycle. The
  burning of wood and fossil fuels like coal and
  oil adds more CO2 to the atmosphere. As a
  result, the CO2 level in the atmosphere is
  increasing.

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Average Monthly CO2 1955-2005
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Is CO2 in the atmosphere good or bad?

• It depends on the amount
• Carbon dioxide is a greenhouse gas, which means
  that it traps heat close to the Earths surface
• This makes the Earth warmer

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Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer
21
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer
22
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer
23
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer
24
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer

1. Solar radiation (heat) arrives from the sun and
   enters the Earths atmosphere

25
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer

1. The solar radiation reaches the Earths surface
   where some is absorbed and some is reflected

26
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer

1. The reflected solar radiation goes back into the
   atmosphere. Some escapes into space and some is
   trapped by greenhouse gasses like CO2.

27
Carbon dioxide is a greenhouse gas which means
that it traps heat close to the Earths surface
which makes it warmer

1. The trapped solar radiation warms the Earth.
   Normally, this is good. Without the greenhouse
   effect, Earth would be too cold to support life.

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Too much of a good thing?

• More CO2 in the atmosphere means more heat is
  trapped which means the average temperature of
  the Earth increases.
• I like warm days so why should I be concerned
  about an increase in average global temperatures?

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Consequences of Global Warming

• Sea-level rise (coastal flooding)
• Drought and Wildfire increase
• Deadly heat waves
• Spread of disease (mosquito range expanded)
• More powerful hurricanes
• Ecosystem disruption/species die-offs

30
Is Global Warming a fact?

• Yes
• The Earth is definitely getting warmer, and is
  expected to continue to do so in the future
• The real debate is whether or not humans are
  contributing to global warming, and if so, what
  should be done about it

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Intergovernmental Panel on Climate Change (IPCC)
Conclusion

• The IPCC concludes that most of the observed
  temperature increase since the middle of the 20th
  century was very likely caused by increasing
  concentrations of greenhouse gases which they
  believe result from human activity such as fossil
  fuel burning and deforestation.
• Greater than 90 likelihood that most warming
  over the last 50 years has occurred because of
  human-caused emissions

33
But some skeptic scientists believe

• that the temperature increase has not been
  caused by an increase in greenhouse gases OR
• that the increase in greenhouse gases has not
  been caused by human activity
• Could it all be part of a larger natural warming
  cycle?

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What should humans do?

• Carry on as usual and hope for the best?
• Stop burning fossil fuels?
• Figure out ways to adapt to higher average global
  temperatures?

35
Concerned?

• Use less stuff and convince others to do the same
  You must be the change you wish to see in the
  world