IB BIO TOPIC 5.2 : THE GREENHOUSE EFFECT

Question 1

List the processes involved in the carbon cycle :

Answer 1

• interaction of living organisms and the biosphere through:
1. photosynthesis
2. cell respiration
3. fossilization
4. combustion
• recall of quantitative data is not required

Question 2

What is the significance of carbon dioxide ?

Answer 2

1. Only one part in 300 of the atmosphere is carbon dioxide. A very substantial tree is made from what seems like a few insubstantial air molecules
2. The substance of all land plants comes from it. Plants use photosynthesis to make themselves from water, carbon dioxide and energy from the Sun
3. Atmospheric oxygen is a byproduct of photosynthesis. Animals reverse this process. They eat plants or they eat animals that eat plants. Animal metabolism consumes oxygen and releases carbon dioxide and water.
4. The net effect of all this is a constant movement of carbon between plants, animals and the atmosphere.

Question 3

Define the importance of Greenhouse gases:

Answer 3

Carbon dioxide and water vapour are the most important greenhouse gases. Without greenhouse gases, Earth would be an ice planet and there would be no life.

Question 4

Explain that Greenhouse effect is a natural phenomenon

Answer 4

1. transmission of incoming shorter-wave radiation through atmospheric
   gasses
2. re-radiation of longer-wave radiation is reflected back to Earth by
   greenhouse gasses

Question 5

What are the causes of enhanced greenhouse effect: in relation to carbon dioxide :

Answer 5

1. carbon dioxide: redistribution of carbon dioxide within the carbon cycle,
   concentrating increasing amounts of carbon dioxide in the atmosphere § fossil fuel combustion
   § rain forest clearing & combustion

Question 6

What are the causes of enhanced greenhouse effect: in relation to methane

Answer 6

methane: increasing methane concentrations in the atmosphere
§ emissions by agricultural rice paddy methanogen bacteria
§ emissions by intestinal methanogen bacteria in livestock

Question 7

What are the causes of enhanced greenhouse effect: in relation to nitrogen oxides& ozones :

Answer 7

nitrogen oxides & ozone: increasing ozone and NOx concentrations in atmosphere
§ fossil fuel combustion

Question 8

What are the causes of enhanced greenhouse effect: in relation to chlorofluorocarbons

Answer 8

4. chlorofluorocarbons: increasing CFC concentrations in atmosphere
§ refrigerants
§ coolants
§ air conditioners
§ cleaning solvents
§ aerosols and propellents

Question 9

Outline the 3 precautionary principle.

Answer 9

• “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
• if the possible consequences of rapid global warming are devastating enough, preventive measure are justified even if it is far from certain that rapid global warming will result from current human activities

Question 10

Evaluate the 5 precautionary principle as a justification for strong action in response to the threats posed by the enhanced greenhouse effect.

Answer 10

• 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
• is it right to knowingly damage the habitat of, and possibly drive to extinction, species other than humans?
• only through international cooperation can a solution be found
• there is inequality between those in the world who are contributing most to the
problem and those who will be most harmed

Question 11

6. Outline the 5 consequences of a global temperature rise on arctic ecosystems.

Answer 11

• 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
• increased success of pest species, including pathogens