1. THE GREENHOUSE EFFECT
Topic 5.2
IB Biology
Miss Werba

2. TOPIC 5 – ECOLOGY and EVOLUTION
5.1 COMMUNITIES and ECOSYSTEMS
5.2
THE GREENHOUSE EFFECT
5.3
POPULATIONS
5.4
EVOLUTION
5.5 CLASSIFICATION
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3. THINGS TO COVER The carbon cycle
Changes in atmospheric carbon dioxide levels
Relationship between gas concentrations and the enhanced greenhouse effect
The precautionary principle
Use of precautionary principle to justify action
Effects of global warming on arctic ecosystems
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4. THE GREENHOUSE EFFECT
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5. THE CARBON CYCLE Command term: DRAW and LABEL
5.2.1
THE CARBON CYCLE Command term: DRAW and LABEL
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6. THE CARBON CYCLE Command term: DRAW and LABEL
5.2.1
THE CARBON CYCLE Command term: DRAW and LABEL
The carbon cycle includes:
Photosynthesis
Cell respiration
Combustion
Fossilisation
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7. THE CARBON CYCLE Command term: DRAW and LABEL
5.2.1
THE CARBON CYCLE Command term: DRAW and LABEL
Photosynthesis removes CO2 from the atmosphere
Cell respiration, combustion and fossilisation all lead to an increase in levels of CO2
Human impact is increasing the release of CO2 into the environment
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8. CARBON EMISSIONS Command term = ANALYSE
5.2.2
CARBON EMISSIONS Command term = ANALYSE
The trends in atmospheric gases are studied as indicators of potential climate change.
Major gases studied include carbon dioxide, methane and oxides of nitrogen which are collectively called the greenhouse gases .
The analysis of carbon dioxide trends is complex.
eg. there are seasonal fluctuations in levels of atmospheric CO2
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9. CARBON EMISSIONS Command term = ANALYSE
5.2.2
CARBON EMISSIONS Command term = ANALYSE
Data taken from Vostok, Antarctica
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10. CARBON EMISSIONS Command term = ANALYSE
5.2.2
CARBON EMISSIONS Command term = ANALYSE
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11. CARBON EMISSIONS Command term = ANALYSE
5.2.2
CARBON EMISSIONS Command term = ANALYSE
Long-term Trends:
CO2 levels fluctuate with ice ages and warm ages
Short-term Trends:
CO2 levels are higher than any time in last 400,000 years (and are still rising)
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12. ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
5.2.3
ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
Greenhouse gases are naturally occurring and include atmospheric CO2, methane (CH4) & oxides of nitrogen
Radiation from sun enters the atmosphere as short waves (light) and is re-radiated as long waves (heat)
The atmospheric gases trap the long-wave radiation, heating the Earth - this is the greenhouse effect
Greenhouse gases levels are rising due to human influence (industrialization, deforestation, urbanisation, etc.)
This enhanced greenhouse effect is potentially increasing global temperatures and causing climate change
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13. ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
5.2.3
ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
Global temperatures and atmospheric CO2 have both been rising since the 1960s
This correlation does not establish a causal relationship !!!
ie. cannot “prove” that one causes the other
Many factors however suggest that rising atmospheric CO2 levels are at least partly responsible
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14. ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
5.2.3
ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
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15. PRECAUTIONARY PRINCIPLE
5.2.4 – 5.2.5
PRECAUTIONARY PRINCIPLE
“If an action has a risk of causing harm to the public or environment then, in the absence of scientific consensus, the onus falls upon those advocating action to prove it is not harmful.”
Environmental action is hard to justify scientifically b/c they can’t prove the outcome of this action.
Principle means that they don’t have to prove what it will do, just that it wont do anything harmful!
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16. PRECAUTIONARY PRINCIPLE
5.2.4 – 5.2.5
PRECAUTIONARY PRINCIPLE
Arguments For Climate Action:
Inaction could result in potential droughts or floods, rising sea levels, higher spread of disease or loss of biodiversity.
Inaction could affect food production/industry, leading to economic depression, and possible famine, unemployment or global poverty.
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17. PRECAUTIONARY PRINCIPLE
5.2.4 – 5.2.5
PRECAUTIONARY PRINCIPLE
Arguments Against Climate Action:
Reducing emissions may impact on economic growth in developing countries
International political relations from noncompliant nations
Cutting carbon emissions may impact on future technology and scientific research
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18. PRECAUTIONARY PRINCIPLE Applied to wind power
5.2.4 – 5.2.5
PRECAUTIONARY PRINCIPLE Applied to wind power
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19. PRECAUTIONARY PRINCIPLE Applied to wind power
5.2.4 – 5.2.5
PRECAUTIONARY PRINCIPLE Applied to wind power
PROS
CONS
Supplies renewable energy source
Reduces burning of fossil fuels
Creates jobs
Causes noise pollution
Causes visual pollution of the landscape
Kills birds that fly into them
So how to we decide what action to take?
Prioritise possibilities:
Immediate dangers should be dealt with before causes that are dangerous later on
Human life comes before environmental concerns
The more likely something is of becoming a threat the more we need to deal with it
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20. 5.2.6
ARCTIC ECOSYSTEMS
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21. 5.2.6
ARCTIC ECOSYSTEMS
The average temp in the Arctic region is rising at twice the speed of the rest of the world.
The polar cap is shrinking as a result.
The snow and ice cover the Arctic reflects much of the Earth’s radiation.
When this melts, the Arctic will absorb more heat and warm up even faster (+ve feedback loop).
This may also release CO2 stored in ocean (increasing warming).
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22. ARCTIC ECOSYSTEMS Diminished snow cover and permafrost
5.2.6
ARCTIC ECOSYSTEMS
Diminished snow cover and permafrost
Increased decomposition of detritus and burning of fuels (once trapped in permafrost)
Expansion of ranges of habitats available to temperate species (loss of tundra)
Increased success of pest species and pathogens (leads to extinction of native species)
Changed behaviours of native species (e.g. migration, hibernation, birth cycles)
Extinction and loss of biodiversity
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23. Sample questions
Q1 If humans become infected with the Ebola virus it can have devastating effects. Strong, but not certain, evidence suggests that trading in animal products is the main reason for the spread of the Ebola virus to humans. Which statement about the precautionary principle is correct?
In the absence of certainty about cause and effect, people should not be asked to stop trading in animal products.
The burden of proof regarding a cause and effect relationship lies with scientists.
Because it is a probable cause, trading in animal products should be banned because of the potentially devastating consequences.
The precautionary principle is not relevant in this case.
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24. Sample questions
A1 C
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25. Sample questions
Q2 Below is a graph of atmospheric CO2 levels measured at Mauna Loa Observatory, Hawai’i.
Explain the observed changes in atmospheric CO2 concentration from 1960 to [3]
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26. Sample questions A2
(from 1960–2005) atmospheric CO2 concentration increases/strong positive trend / increase between 1960–2005 of 65 ppm/figures to that effect; CO2 released by human activities contributes to the increase; examples of human activities e.g. combustion of fossil fuels / deforestation; seasonal/annual fluctuations (do not prevent long-term increase);
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