1. 5.2 The Greenhouse Effect
Topic 5 – Ecology & Evolution

2. The Greenhouse Effect
• 5.2.1 Draw and label a diagram of the carbon cycle to
show the processes involved.
• The details of the carbon cycle should include the
interaction of living organisms and the biosphere through
the processes of photosynthesis, cell respiration,
fossilization and combustion. Recall of specific
quantitative data is not required.
• TOK: What difference might it make to scientific work if
nature were to be regarded as a machine, for example,
as a clockwork mechanism, or as an organism, that is,
the Gaia hypothesis? How useful are these metaphors?

3. The Greenhouse Effect
• 5.2.2 Analyse the changes in concentration of
atmospheric carbon dioxide using historical records.
• Data from the Mauna Loa, Hawaii, or Cape Grim,
Tasmania, monitoring stations may be used.
• 5.2.3 Explain the relationship between rises in
concentrations of atmospheric carbon dioxide, methane
and oxides of nitrogen and the enhanced greenhouse
effect.

4. The Greenhouse Effect
• Students should be aware that the greenhouse effect is
a natural phenomenon. Reference should be made to
transmission of incoming shorter-wave radiation and reradiated longer-wave radiation. Knowledge that other
gases, including methane and oxides of nitrogen, are
greenhouse gases is expected.

5. The Greenhouse Effect
• 5.2.4 Outline the precautionary principle.
• The precautionary principle holds that, if the effects of a
human-induced change would be very large, perhaps
catastrophic, those responsible for the change must
prove that it will not do harm before proceeding. This is
the reverse of the normal situation, where those who are
concerned about the change would have to prove that it
will do harm in order to prevent such changes going
ahead.

6. The Greenhouse Effect
• TOK: Parallels could be drawn here between success in
deterring crime by increasing the severity of the
punishment or by increasing the chance of detection. If
the possible consequences of rapid global warming are
devastating enough, preventive measures are justified
even if it is far from certain that rapid global warming will
result from current human activities.

7. The Greenhouse Effect
• 5.2.5 Evaluate the precautionary principle as a
justification for strong action in response to the threats
posed by the enhanced greenhouse effect.
• Aim 8: Consider whether the economic harm of
measures taken now to limit global warming could be
balanced against the potentially much greater harm for
future generations of taking no action now. There are
also ethical questions about whether the health and
wealth of future human generations should be
jeopardized, and whether it is right to knowingly damage
the habitat of, and possibly drive to extinction, species
other than humans.

8. The Greenhouse Effect
• The environmental angle here is that the issue of global
warming is, by definition, a genuinely global one in terms
of causes, consequences and remedies. Only through
international cooperation will a solution be found. There
is an inequality between those in the world who are
contributing most to the problem and those who will be
most harmed.

9. The Greenhouse Effect
• 5.2.6 Outline the consequences of a global temperature
rise on arctic ecosystems.
• Effects include increased rates of decomposition of
detritus previously trapped in permafrost, expansion of
the range of habitats available to temperate species, loss
of ice habitat, changes in distribution of prey species
affecting higher trophic levels, and increased success of
pest species, including pathogens.

11. Key processes in the Carbon cycle
•
•
•
•
•
Combustion
Cell respiration
Photosynthesis
Fossilisation
Interaction between living organisms

12. The layers of
the
atmosphere
The troposphere is the part of the
atmosphere in the biosphere
The stratosphere contains the
ozone layer
The stratosphere is also a zone of
warm air that keeps a lid on the
troposphere. It does not mix with
the upper atmosphere
© Text 2007 Paul Billiet ODWS
© Windows to the Universe

13. The Greenhouse Effect
• Earth has a natural greenhouse effect
• This is important to prevent large
fluctuations in temperature
• Without a greenhouse effect on Earth, we
would not have life as we know it.

15. Greenhouse Effect
Light from the sun has short wavelengths
and can pass through most of the
atmosphere.
This sunlight warms the Earth which in turn
emits long wave radiation.
This long wave radiation is bounced back by
the greenhouse gases, such as carbon
dioxide, methane, CFCs, water vapour,
and sulphur dioxide

16. The Greenhouse Effect
• The molecules of some gases in the
atmosphere absorb heat energy and
retain it
• This can be a good thing
• Without an atmosphere the Earth would
have same temperature as the moon
• Moon mean surface temperature -46°C
• Moon temperature range: -233 to +123°C
© 2007 Paul Billiet ODWS

17. The Greenhouse Gases
• H2O vapour
• CO2
• CH4
• NOx
• CFC
© Oceanworld 2005 Robert R Stewart
© Text 2007 Paul Billiet ODWS

18. The Greenhouse Gases
• Water vapour in the atmosphere is stable
• The atmosphere is saturated
• CO2 levels are currently rising
• They have varied in the past
• Methane levels are increasing:
as more cattle are farmed, as more paddy
fields are planted, as permafrost melts
• NOx levels increase due to increased
circulation of motor vehicles
© 2007 Paul Billiet ODWS

19. Mauna Loa Observatory
© Mauna Loa Observatory Site
© Earth
System Research Laboratory
© Earth System Research Laboratory

20. Carbon dioxide a greenhouse
gas
© Mauna Loa Observatory Site

21. South Pole Data

22. Samoa data

23. © Australian Antarctic Division
© New Scientist : Environment

24. Levels during the last ice age
© Dennis Hartmann: Universoty of Washington: Department of Atmospheric Sciences

25. Out of the ice age

26. Since the Industrial
Revolution
Concentration of Carbon Dioxide from trapped air measurements for the DE08 ice core near the summit
of Law Dome, Antarctica. (Data measured by CSIRO Division of Atmospheric Research from ice cores supplied by
Australian Antarctic Division)

27. Is it really getting warmer
1979
© NASA
2003

28. 5.2
The ENHANCED greenhouse
effect
Phenomenon
The mean global temperature has
risen about 1 degree Celsius since
1856. We saw an increase
between 1910 and 1940, and from
1970 onwards.

29. 5.2
Enhancing the greenhouse
Effect
Human Activities
• Increased burning of fossil fuels releasing greenhouse
gases (CO2, oxides of Nitrogen)
• Deforestation – less trees to convert CO2 back to O2
• Raising cattle and paddy fields release methane
• CFCs were used as a propellant in aerosols and as a
coolant in refrigerators, freezers and air conditioning
units. Old cooling machinery can still leak CFCs and
need to be disposed of carefully – CFCs are persistent
• Other industrial activities that release other
greenhouse gases

30. The Precautionary Principle
• The precautionary principle holds that, if the
effects of a human-induced change would be
very large, perhaps catastrophic, those
responsible for the change must prove that it
will not do harm before proceeding.
• This is the reverse of the normal situation where
those who are concerned about the change
would have to prove that it will do harm in order
to prevent such changes going ahead.

31. Evaluate the precautionary
principle…
• …..as a justification for strong action in response to the
threats posed by the enhanced greenhouse effect
• Economic harm Vs harm to environment for future
generations
• Should the health and wealth of future generations be
jeapardised?
• Is it right to knowingly damage the habitat of species
other than humans? Cause extinction?
• Need for international cooperation
• Inequality between those contributing most to the harm,
and those who will be most harmed

32. The consequences
• Sea level rise
Changing sea ice...
• Flooding coastal areas
Reduced agricultural land
Displacement of populations
• Climate change and changing weather patterns
• Displacement of ecosystems
Change in range of insect vectors of pathogens
Reduced biodiversity
© 2007 Paul Billiet ODWS

33. The consequences
• Increased rates of photosynthesis
• Increased agricultural production at high
latitudes
• BUT faster growth means:
less protein in cereals
trees taller and more exposed to storm
damage
© 2007 Paul Billiet ODWS

34. •
•
•
•
Knock-on effects
Increased temperature melts the permafrost
Frozen plant remains decompose
More methane released
Similarly soils will lose organic carbon (humus)
more rapidly in a warmer climate
• Ice caps melt more sea exposed
• Snow reflects light (high albedo)
• Water absorbs light, increases warming
• More CO2 dissolving in water lowers pH
• Currently this is buffered and remains stable
• Eventually pH will drop sea life will die CO2
© 2007 Paul Billiet ODWS as organisms decompose
produced

35. What can be done?
Reduce carbon emissions
• Improve mass transport systems (public
transport)
• Design more efficient motors
• Design alternative power sources
• Hydrogen powered motors
BUT problems of fuel reservoir, delivery,
fabrication
• Renewable energy (wind, tidal, hydro,
geothermal, biomass)
BUT growing crops for biofuel reduces farmland
available for food
Hydroelectric dams disrupt river ecosystems
•© 2007 Paul Billiet ODWS
Nuclear power

36. What can be done?
Increase natural CO2 sequestering
• Reduce deforestation
• Increase reforestation
© 2007 Paul Billiet ODWS

37. What can be done?
Artificial CO2 sequestering
• Filter CO2 sources using hydroxide
scrubbers
• Injection of CO2 into deep ocean layers
Forms CO2 reservoirs
Impact on sea life unknown
• Injecting CO2 into disused oil wells
• Mineral deposition as carbonates
© 2007 Paul Billiet ODWS

38. The bottom line
Two factors will ultimately govern what happens:
1. Human population growth
More people means greater demand for nonrenewable resources
2. The ecological footprint of each individual
human
Higher standards of living usually means higher
consumption of fossil fuels
The planet will look after itself in the end
There are plenty of examples where human
communities have disappeared because they
outstripped the environmental resources
© 2007 Paul Billiet ODWS

39. The planet will look after itself in
the end
• Easter Island (Rapanui) in
the Pacific
• Settled between AD900 and
1200
• Community in severe
decline AD 1700
• Cause: excessive
deforestation
The Moai statues, Easter Island © Martin Gray, World Mysteries
© Text 2007 Paul Billiet ODWS

40. The planet will look after itself in
the end
• Chaco Canyon, New
Mexico
• Anasazi culture
• AD 850 – 1250
• Cause: Deforestation
combined with a
decline in rainfall
© New Mexico Tourism Department
© Text 2007 Paul Billiet ODWS

41. The planet will look after itself in
the end
•
•
•
•
Mesopotamia
Sumerian civilization
3100 – 1200 BC
Increased salt levels
in soil due to irrigation
systems & arid
environment
• Reduced food yield
© Text 2007 Paul Billiet ODWS
© Asociación Cultural Nueva Acrópolis en Barcelona

42. The planet will look after itself in
the end
•
•
•
•
Greenland
Viking colony
AD982 – 1350
Cause: Deforestation,
soil degradation &
cooling of the climate
© Emporia State University
© Text 2007 Paul Billiet ODWS

43. Who’s next?
forumpolitics.com/pics/earth-photo.jpg
© NASA

44. 5.2 The Greenhouse Effect
The IBO assessment statements:

45. The Greenhouse Effect
• 5.2.1 Draw and label a diagram of the carbon cycle to
show the processes involved.
• The details of the carbon cycle should include the
interaction of living organisms and the biosphere through
the processes of photosynthesis, cell respiration,
fossilization and combustion. Recall of specific
quantitative data is not required.
• TOK: What difference might it make to scientific work if
nature were to be regarded as a machine, for example,
as a clockwork mechanism, or as an organism, that is,
the Gaia hypothesis? How useful are these metaphors?

46. The Greenhouse Effect
• 5.2.2 Analyse the changes in concentration of
atmospheric carbon dioxide using historical records.
• Data from the Mauna Loa, Hawaii, or Cape Grim,
Tasmania, monitoring stations may be used.
• 5.2.3 Explain the relationship between rises in
concentrations of atmospheric carbon dioxide, methane
and oxides of nitrogen and the enhanced greenhouse
effect.

47. The Greenhouse Effect
• Students should be aware that the greenhouse effect is
a natural phenomenon. Reference should be made to
transmission of incoming shorter-wave radiation and reradiated longer-wave radiation. Knowledge that other
gases, including methane and oxides of nitrogen, are
greenhouse gases is expected.

48. The Greenhouse Effect
• 5.2.4 Outline the precautionary principle.
• The precautionary principle holds that, if the effects of a
human-induced change would be very large, perhaps
catastrophic, those responsible for the change must
prove that it will not do harm before proceeding. This is
the reverse of the normal situation, where those who are
concerned about the change would have to prove that it
will do harm in order to prevent such changes going
ahead.

49. The Greenhouse Effect
• TOK: Parallels could be drawn here between success in
deterring crime by increasing the severity of the
punishment or by increasing the chance of detection. If
the possible consequences of rapid global warming are
devastating enough, preventive measures are justified
even if it is far from certain that rapid global warming will
result from current human activities.

50. The Greenhouse Effect
• 5.2.5 Evaluate the precautionary principle as a
justification for strong action in response to the threats
posed by the enhanced greenhouse effect.
• Aim 8: Consider whether the economic harm of
measures taken now to limit global warming could be
balanced against the potentially much greater harm for
future generations of taking no action now. There are
also ethical questions about whether the health and
wealth of future human generations should be
jeopardized, and whether it is right to knowingly damage
the habitat of, and possibly drive to extinction, species
other than humans.

51. The Greenhouse Effect
• The environmental angle here is that the issue of global
warming is, by definition, a genuinely global one in terms
of causes, consequences and remedies. Only through
international cooperation will a solution be found. There
is an inequality between those in the world who are
contributing most to the problem and those who will be
most harmed.

52. The Greenhouse Effect
• 5.2.6 Outline the consequences of a global temperature
rise on arctic ecosystems.
• Effects include increased rates of decomposition of
detritus previously trapped in permafrost, expansion of
the range of habitats available to temperate species, loss
of ice habitat, changes in distribution of prey species
affecting higher trophic levels, and increased success of
pest species, including pathogens.