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THE GREENHOUSE EFFECT Topic 5.2 IB Biology Miss Werba.

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Presentation on theme: "THE GREENHOUSE EFFECT Topic 5.2 IB Biology Miss Werba."— Presentation transcript:

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 J WERBA – IB BIOLOGY 2

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 J WERBA – IB BIOLOGY 3

4 THE GREENHOUSE EFFECT J WERBA – IB BIOLOGY 4

5 THE CARBON CYCLE Command term: DRAW and LABEL
5.2.1 THE CARBON CYCLE Command term: DRAW and LABEL J WERBA – IB BIOLOGY 5

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 J WERBA – IB BIOLOGY 6

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 J WERBA – IB BIOLOGY 7

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 J WERBA – IB BIOLOGY 8

9 CARBON EMISSIONS Command term = ANALYSE
5.2.2 CARBON EMISSIONS Command term = ANALYSE Data taken from Vostok, Antarctica J WERBA – IB BIOLOGY 9

10 CARBON EMISSIONS Command term = ANALYSE
5.2.2 CARBON EMISSIONS Command term = ANALYSE J WERBA – IB BIOLOGY 10

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) J WERBA – IB BIOLOGY 11

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 J WERBA – IB BIOLOGY 12

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 J WERBA – IB BIOLOGY 13

14 ATMOSPHERIC GASES & THE GREENHOUSE EFFECT
5.2.3 ATMOSPHERIC GASES & THE GREENHOUSE EFFECT J WERBA – IB BIOLOGY 14

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! J WERBA – IB BIOLOGY 15

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. J WERBA – IB BIOLOGY 16

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 J WERBA – IB BIOLOGY 17

18 PRECAUTIONARY PRINCIPLE Applied to wind power
5.2.4 – 5.2.5 PRECAUTIONARY PRINCIPLE Applied to wind power J WERBA – IB BIOLOGY 18

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 J WERBA – IB BIOLOGY 19

20 5.2.6 ARCTIC ECOSYSTEMS J WERBA – IB BIOLOGY 20

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). J WERBA – IB BIOLOGY 21

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 J WERBA – IB BIOLOGY 22

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. J WERBA – IB BIOLOGY 23

24 Sample questions A1 C J WERBA – IB BIOLOGY 24

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] J WERBA – IB BIOLOGY 25

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); J WERBA – IB BIOLOGY 26


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