| Date | May 2016 | Marks available | 2 | Reference code | 16M.1.SL.TZ0.5 |
| Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 0 |
| Command term | Explain | Question number | 5 | Adapted from | N/A |
Question
Figure 6: The graph below shows the global CO2 emissions from 1992 to 2012.
Figure 6
[Source: Adapted from http://infographics.pbl.nl/website/globalco2-2015/, Olivier JGJ et al. (2015), Trends in global CO2 emissions; 2015 Report, The Hague: PBL Netherlands Environmental Assessment Agency; Ispra: European Commission, Joint Research Centre]
Calculate the percentage increase of global CO2 emissions from 1992 to 2012.
CO2 is considered a greenhouse gas. Identify two other greenhouse gases.
Natural systems achieve equilibrium through feedback systems. Explain how feedback mechanisms would be associated with an increase in mean global temperature.
Markscheme
51%–60%
[1 max]
methane/CH4;
water vapour/H2O;
nitrous oxides/N2O;
tropospheric ozone/O3;
chlorofluorocarbons (CFCs)/hydrofluorocarbons (HFCs)/ perfluorocarbons (PFCs).
Do not accept ‘sulphur dioxide/carbon monoxide/nitrogen oxides (NOx)’.
[2 max]
Positive feedback amplifies/increases change /Negative feedback counteracts change;
Example of positive feedback:
increase in temperature, increases thawing of permafrost and release of methane which further raises the temperature;
increase in temperature increases the amount of water evaporating, raising the levels of GHG and subsequently global temperature;
increase in temperature melts ice and snow which reduces the albedo effect (amount of sunlight reflected back subsequently resulting in increase in solar energy absorbed) that further enhances the temperature;
Example of where increase in temperature can lead to negative feedback:
increase in temperature leads to more evaporation resulting in increased snowfall which in turn increases the Earth’s albedo and lowers temperature/returns temperature to ‘normal’;
increase in temperature can lead to enhancing photosynthesis and the uptake of carbon dioxide by plants, this is turn will reduce atmospheric levels of carbon dioxide/GHGs resulting in lowering of global temperature;
Max of 1 mark for definition of positive/negative feedback.
Max of 2 marks for two examples.
[2 max]
Examiners report
A significant number of candidates incorrectly carried out this calculation for percentage increase resulting in a wrong answer.
Most candidates answered this question well.
Responses varied widely for this question. Although there were some very good responses, some candidates had a poor understanding of positive or negative feedback mechanisms. Some answers were too generalised and did not refer to global temperature.
Syllabus sections
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16N.2.SL.TZ0.5b:
Explain the impact of global warming and ozone depletion on coastal ecosystems.
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18N.2.SL.TZ0.6b:
In 2016, the Earth’s atmospheric levels of carbon dioxide reached 400 ppm. Suggest the potential impacts of high levels of greenhouse gases on human societies in different locations.
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19N.1.SL.TZ0.2e:
Suggest why the St Lawrence River beluga whale population has not recovered despite being given protected status in 1983.
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16N.2.SL.TZ0.5a:
Distinguish between the causes of recent global warming and those of ozone depletion.
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18M.2.SL.TZ0.1b:
State a greenhouse gas other than CO2.
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19N.1.SL.TZ0.5:
With reference to information in the resource booklet, evaluate the sustainability of Canada’s management of the Large Ocean Management Area of the St Lawrence River estuary and Gulf of St Lawrence.
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14M.1.SL.TZ0.5c:
Evaluate contrasting human perceptions of the issue of global warming.
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14M.2.SL.TZ0.3c:
The long term effects of global warming may influence the carrying capacity for human populations.
Discuss whether global warming is likely to increase or decrease carrying capacity for human populations around the world. Support your conclusion with valid reasons or evidence.
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14N.2.SL.TZ0.2a:
Distinguish between negative and positive feedback using examples from environmental systems.
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14N.2.SL.TZ0.5b:
Evaluate the use of models for predicting climate change.
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17N.1.SL.TZ0.5c:
Identify two reasons why the future size of the Atlantic puffin population is difficult to predict.
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19N.2.SL.TZ0.7c:
To what extent do the approaches and strategies of different environmental value systems improve access to fresh water?
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19N.2.SL.TZ0.5c:
To what extent is pollution impacting human food production systems?
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19M.1.SL.TZ0.9:
Outline two possible effects of climate change on marine coastal ecosystems within the Coral Triangle.
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18M.2.SL.TZ0.4c:
Disturbance of the composition and processes of the atmospheric system through human activity always disturbs the equilibria of marine systems.
Discuss the validity of this statement with reference to named examples.
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19N.1.SL.TZ0.3c:
With reference to Figure 9(a), explain why the realized niche of the mottled sculpin has changed in recent years.
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15N.1.SL.TZ0.6a.i:
Identify one factor that may be causing long-term changes in sea ice cover.
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17N.1.SL.TZ0.4:
Evaluate the possible impacts of climate change on Iceland.
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17M.2.SL.TZ0.3b:
Outline how CO2 emissions may cause a change in the global climate.
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19N.2.SL.TZ0.7b:
Explain, with the use of a system diagram, how human activities affect flows in the global water cycle.
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18M.2.SL.TZ0.1a:
Outline the evidence that CO2 acts as a greenhouse gas.
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14N.2.SL.TZ0.5c:
Tundra ecosystems are vulnerable to the effects of global warming. Discuss the response of two contrasting environmental value systems to the effects of global warming on the tundra.
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16M.1.SL.TZ0.5a.ii:
CO2 is considered a greenhouse gas. Identify two other greenhouse gases.
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16M.1.SL.TZ0.5a.i:
Calculate the percentage increase of global CO2 emissions from 1992 to 2012.
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19M.2.SL.TZ0.4c:
Climate can both influence, and be influenced by, terrestrial food production systems.
To what extent can terrestrial food production strategies contribute to a sustainable equilibrium in this relationship?
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18M.2.SL.TZ0.6a:
With reference to named examples, distinguish between a primary and secondary pollutant.
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16N.2.SL.TZ0.4b:
Explain two factors which lead to a loss of marine (ocean) biodiversity.
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16M.2.SL.TZ0.4c:
The impacts of acid rain on terrestrial ecosystems may include acidified soils, leaching of nutrients, release of toxins and damage to vegetation. The impacts of global warming on these systems may include desertification, flooding, loss of species and shifting of biomes.
For terrestrial ecosystems, discuss the difficulty of managing the impacts of acid rain compared to that of managing the impacts of global warming.
- 18N.2.SL.TZ0.7c: Examine the driving factors behind the changing energy choices of different countries using...
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17N.2.SL.TZ0.4b:
Explain the potential impact of ocean acidification on environmental systems and societies.
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17N.1.SL.TZ0.3c:
With reference to Figures 6(c), 7(a) and 7(b) explain the problems associated with land restoration in Iceland.
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15M.2.SL.TZ0.4c:
Discuss how global warming may affect the distribution and diversity of ecosystems.
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15N.1.SL.TZ0.6a.iii:
Describe the trend seen in the sea ice cover data in Figure 4(b).
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18N.2.SL.TZ0.1b:
Outline how climate change may affect the availability of freshwater resources.
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15N.1.SL.TZ0.6a.ii:
Calculate the percentage change in sea ice cover from March 1979 to March 2012 and from September 1979 to September 2012 in Figure 4(c).
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17N.2.SL.TZ0.7c:
Discuss the role of humans in the destabilization of ecological systems.
