5.2 the greenhouse effect

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5.2 the greenhouse effect

  1. 1. 5.2 The Greenhouse Effect Topic 5 – Ecology & Evolution
  2. 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. 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. 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. 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. 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. 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. 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. 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.
  10. 10. Key processes in the Carbon cycle • • • • • Combustion Cell respiration Photosynthesis Fossilisation Interaction between living organisms
  11. 11. 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
  12. 12. 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.
  13. 13. 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
  14. 14. 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
  15. 15. The Greenhouse Gases • H2O vapour • CO2 • CH4 • NOx • CFC © Oceanworld 2005 Robert R Stewart © Text 2007 Paul Billiet ODWS
  16. 16. 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
  17. 17. Mauna Loa Observatory © Mauna Loa Observatory Site © Earth System Research Laboratory © Earth System Research Laboratory
  18. 18. Carbon dioxide a greenhouse gas © Mauna Loa Observatory Site
  19. 19. South Pole Data
  20. 20. Samoa data
  21. 21. © Australian Antarctic Division © New Scientist : Environment
  22. 22. Levels during the last ice age © Dennis Hartmann: Universoty of Washington: Department of Atmospheric Sciences
  23. 23. Out of the ice age
  24. 24. 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)
  25. 25. Is it really getting warmer 1979 © NASA 2003
  26. 26. 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.
  27. 27. 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
  28. 28. 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.
  29. 29. 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
  30. 30. 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
  31. 31. 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
  32. 32. • • • • 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
  33. 33. 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
  34. 34. What can be done? Increase natural CO2 sequestering • Reduce deforestation • Increase reforestation © 2007 Paul Billiet ODWS
  35. 35. 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
  36. 36. 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
  37. 37. 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
  38. 38. 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
  39. 39. 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
  40. 40. 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
  41. 41. Who’s next? forumpolitics.com/pics/earth-photo.jpg © NASA
  42. 42. 5.2 The Greenhouse Effect The IBO assessment statements:
  43. 43. 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?
  44. 44. 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.
  45. 45. 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.
  46. 46. 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.
  47. 47. 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.
  48. 48. 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.
  49. 49. 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.
  50. 50. 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.

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