IB ESS HL 6.2 Climate Change Causes and Impacts Questions

Practise IB ESS HL 6.2 by linking emissions and climate evidence to feedback loops, model uncertainty, climate impacts and unequal community vulnerability.

Exam points

Calculate or compare anthropogenic CO₂ emissions and carbon footprints across years, sectors or development levels.
Explain how human emissions enhance greenhouse warming, distinguishing this mechanism from other drivers of climate trends.
Explain climate feedbacks through albedo, cloud and methane loops, identifying when warming is amplified or moderated.
Evaluate climate-data reliability from measurement methods and uncertainty in pollutant or sea-level observations.
Evaluate climate models as simplified, data-based predictions by weighing their uses, assumptions and limitations.
Explain ecosystem impacts of warming, drought, sea-level rise and extreme events using species, habitat or service examples.
Compare societal impacts and vulnerability through effects on water, health, food, infrastructure and adaptive capacity.
Evaluate climate-justice cases by linking exposure, low-lying location and limited capacity to adapt.

Covered syllabus points

6.2.1—Climate definition 6.2.2—Anthropogenic CO₂ emissions 6.2.3—Ice core, tree ring, sediment data 6.2.4—Enhanced greenhouse effect 6.2.5—Climate change impacts on ecosystems 6.2.6—Climate change impacts on societies 6.2.7—Climate change models 6.2.8—Climate change planetary boundary 6.2.9—Perspectives on climate change 6.2.10 (HL)—Climate data collection 6.2.11 (HL)—Global climate models 6.2.12 (HL)—Climate model scenarios 6.2.13 (HL)—Critical thresholds and tipping points 6.2.14 (HL)—Tipping cascades 6.2.15 (HL)—Climate justice

[Maximum number: 1]

Figure:Global carbon-dioxide emissions from 1992 to 2012

Figure 6: The graph below shows the global CO₂ emissions from 1992 to 2012.

Calculate the percentage increase of global $\mathrm{CO}_{2}$ emissions from 1992 to 2012.

[Maximum number: 1]

Table:Global crude birth and death rates from 2003 to 2011

Figure 9 shows the crude birth rate and the crude death rate per thousand of the global human population between 2003 and 2011.

Outline one way in which a larger world population may cause an increase in the rate of global warming.

larger population uses more energy/fossil fuels, so produces extra carbon dioxide/greenhouse gases;
larger population uses more land for growing food eg rice / keeps more livestock, so produces extra methane/greenhouse gases;
more people results in more respiration increasing $\mathrm{CO}_{2}$ and contributing to global warming

Marking guidance:

Accept other reasonable suggestions.

[Maximum number: 2]

Figure:Fact file on Mindo cloud forest

Figure 10(a): Fact file on Mindo cloud forest
Only one third of Ecuador’s identified cloud forest sites are protected. The Mindo-Nambillo cloud forest reserve forms part of several protected areas across Ecuador. The Mindo cloud forest covers 268 km2 and is home to several indigenous subgroups of the Quichua people. The village of Mindo is west of the reserve and is known for chocolate made from locally grown cacao. Organizations work with local farmers to find alternatives to cattle ranching and with indigenous groups to develop more sustainable agricultural practices, reducing habitat destruction.

Describe two ways in which climate change could affect the cloud forest ecosystem.

[Maximum number: 7]

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.

[Maximum number: 7]

Explain how negative and positive feedback mechanisms play a role in the process of global warming.

Negative feedback loops;
(Increased temperatures...)
a....leads to increased evaporation...;
b. ...which leads to increased cloud cover…;
c....which leads to greater albedo...;
(...which decreases global temperature)
(Increase in global temperatures/ $\mathrm{CO}_{2}$ concentrations...)
d....leads to increased rates of photosynthesis...;
e….which is assimilating more $\mathrm{CO}_{2} \ldots$ ;
f....which is a greenhouse gas/ thus less outgoing heat/emitted long-wave radiation is absorbed...;
(...leading to lower global temperatures/ $\mathrm{CO}_{2}$ concentrations)

Positive feedback loops:
(Increased global temperatures...)
g.... lead to increased evaporation...;
h....which leads to more water vapour...;
i....which is a greenhouse gas/absorbs outgoing heat/emitted long-wave radiation...;
(which increases global temperature);
(Increased global temperatures...)
j....leads to melting of permafrost/glaciers...;
k....leading to increased methane release...;
l....which is a greenhouse gas / absorbs outgoing heat/emitted long-wave radiation...;
(...which increases global temperature)
(Increased global temperatures...)
m....leads to melting of polar ice caps...;
n.... leading to reduced ice/albedo;
o….which leads to less reflection of incoming solar radiation…;
(which increases global temperature);

Allow [1 max] for general description of negative and positive feedback either as a separate knowledge statement or explicitly in e.g.:
negative feedback occurs when increase in global warming promotes reduction/stabilization of global warming and positive feedback occurs when it promotes further increase in global warming;

Allow [2max] per loop given below.

Note: Allow [4max] if only positive or only negative feedback is addressed.
Allow credit for any other valid feedback loops relating to ocean expansion/forest fires/desertification etc.
Credit appropriately annotated drawings.

[Maximum number: 8]

Three levels of pollution management strategies diagram

Pollution management strategies may be applied at any of the three levels identified in the diagram below:

With reference to acid deposition, evaluate the political and economic advantages of applying management strategies at the levels of production and impact of the pollutant.

[Maximum number: 1]

Figure:Annual global mean temperature anomalies from three organizations

Suggest one reason why there are variations between the published data of the three organizations in Figure: Annual global mean temperature anomalies from three organizations.

[Maximum number: 6]

Evaluate the use of models for predicting climate change.

Explanation of models:
models are simplified representations of natural systems that enable predictions for change based on pre-existing data;
climate models are mathematical formulae/computer programmes that scientists/IPCC use to predict future changes in climate based on historic climatic data;
[1 max]

Strengths:
provides information/range of scenarios to policy/decision makers;
allows predictions/extrapolations to be made based on wide input of historic data;
large quantities of data (from a variety of sources) can provide statistical certainty to predictions;
can provide relatively objective information to political/emotional/contentious issues;
can lead to greater understanding of complex relationships between environmental factors;
visualizes projected effects / eg images of projected changes in global average temperatures;
shows that some regions are more vulnerable than others / eg poles might undergo higher temperature increase than the Tropics;

Limitations:
conflicting results from different models can lead to uncertainty/confusion for policy/decision makers;
...and enable politicians to pick those that are most supportive to their cause;
approximations/simplifications are necessary and lead to uncertainties;
only a few experts/not all policy/decision-makers will fully understand the statistical limitations/reliability/application of models;
data used may be inaccurate as in-depth recordings have only been made recently;
data comes from many sources and instrumentation/methodologies may not be consistent/compatible;
models generally rely on assumptions that factors will operate in the way they have historically which may not always be valid;

Appraisal: Award [1 max] for a clear appraisal that is consistent with argument of response. eg while models have significant limitations they are the best available means of planning appropriately for the future;
eg there is so much political manipulation in the current use of models that they are of very limited value;

Marking guidance:

[5 max] if no clear appraisal regarding relative strengths or weaknesses:
[3 max] if only strengths or only limitations are discussed.

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Covered syllabus points

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Question 8