Question 1
Define decarbonization of the economy.
[2]
Question 2
Outline one mitigation strategy from each of the following categories: reducing the warming process, reducing greenhouse gas production, and removing from the atmosphere.
[3]
Question 3
The electricity system of the fictional state of Belvar is undergoing decarbonization. Table 1 shows changes in electricity generation and emissions intensity between 2016 and 2024.
Belvar electricity generation by source, total generation and emissions intensity.
| Year | Coal / % | Natural gas / % | Wind / % | Solar / % | Hydroelectric / % | Total generation / TWh | Emissions intensity / |
|---|---|---|---|---|---|---|---|
| 2016 | 46 | 30 | 8 | 4 | 12 | 80 | 610 |
| 2024 | 20 | 24 | 22 | 22 | 12 | 96 | 350 |
Calculate the decrease in the percentage contribution of fossil fuels to electricity generation between 2016 and 2024.
[2]
Calculate the percentage increase in total electricity generation between 2016 and 2024.
[2]
Explain why the emissions intensity of Belvar's electricity decreased even though total electricity generation increased.
[2]
Question 4
Explain why state sovereignty makes international cooperation on climate change necessary but difficult.
[3]
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Question 5
The figure shows adaptations proposed for a coastal settlement exposed to storm surges and sea-level rise.
Identify one structural adaptation and one non-structural adaptation shown in the figure.
[2]
Distinguish between structural and non-structural climate adaptations.
[2]
Question 6
Outline four stages that should be included when developing a climate change adaptation plan.
[4]
Question 7
Distinguish between the roles of the IPCC, the UNFCCC and a Conference of the Parties (COP) in global climate action.
[3]
Question 8
The coastal city of Puerto Esperanza is developing an adaptation plan. Much of its low-income Riverside district is exposed to storm-surge flooding.
Comparison of four adaptation options for Puerto Esperanza in 2050.
| Adaptation option | Implementation cost / US$ million | Expected annual flood loss / US$ million | Households requiring relocation | Additional information |
|---|---|---|---|---|
| No additional adaptation | 0 | 48 | 0 | — |
| Sea wall | 310 | 14 | 120 | May increase erosion beyond its southern end |
| Mangrove restoration | 45 | 25 | 60 | Provides nursery habitat and stores carbon |
| Managed relocation with setback zoning | 180 | 8 | 4200 | Replacement housing is 8 km inland |
Calculate the percentage reduction in expected annual flood loss achieved by the sea wall compared with no additional adaptation.
[2]
Describe two spatial features that increase the vulnerability of Riverside to storm-surge flooding.
[2]
Distinguish between the sea wall and setback zoning as forms of climate change adaptation.
[2]
Explain how mangrove restoration could provide both adaptation and mitigation benefits.
[3]
Using the map and table, evaluate the use of a combined adaptation plan (using two or more of the listed options) for Puerto Esperanza rather than relying only on the sea wall. Comment on any limitation of the available evidence.
[5]
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Question 9
The state of Lydora has published a plan to decarbonize its electricity and transport systems by 2035.
Figure 2(a): Lydora electricity generation shares in 2020 and planned for 2035.
| Electricity source | 2020 share / % | Planned 2035 share / % |
|---|---|---|
| Coal | 46 | 8 |
| Natural gas | 25 | 18 |
| Wind (renewable) | 12 | 30 |
| Solar (renewable) | 6 | 24 |
| Hydroelectric (renewable) | 4 | 6 |
| Nuclear | 7 | 14 |
Calculate the percentage increase in the renewable share of electricity generation between 2020 and 2035.
[2]
Describe the change in Lydora's greenhouse-gas emissions shown in Figure 2(b).
[2]
Explain why electrifying passenger transport may not fully decarbonize Lydora's economy by 2035.
[3]
Explain how home-insulation grants could contribute to climate change mitigation.
[2]
To what extent does the evidence support Lydora's claim that it has a credible decarbonization plan?
[5]
Question 10
The regional government of Altavera is comparing projects for its 2030 climate mitigation programme.
Comparison of proposed climate-mitigation projects in Altavera.
| Mitigation category | Project | Initial public cost / USD million | Estimated annual benefit / | Additional information |
|---|---|---|---|---|
| Reducing greenhouse-gas production | Building insulation | 90 | 180 | Reaches 48 000 low-income homes and lowers energy bills. |
| Reducing greenhouse-gas production | Solar farms | 210 | 320 | Requires 900 ha of semi-arid land; variable generation needs storage. |
| Reducing the warming process | Pale-roof programme | 18 | 35 | Lowers summer indoor temperature but does not remove atmospheric . |
| Removing atmospheric | Peatland restoration | 38 | 95 | Protects downstream water quality and habitat; some landowners drain sites for grazing. |
| Removing atmospheric | Mixed-native afforestation | 55 | 70 | Takes decades to reach maximum storage and may reduce water yield. |
| Reducing greenhouse-gas production | Carbon capture and storage | 390 | 260 | Stores captured emissions in a monitored deep saline formation but requires additional energy. |
Identify one project from each of the three main categories of climate change mitigation.
[3]
Calculate the initial public cost per tonne of annual greenhouse-gas emissions avoided by the solar-farm project.
[2]
Explain one environmental advantage and one environmental limitation of peatland restoration.
[2]
Explain why the estimated climate benefit of the pale-roof programme is not equivalent to removing tonnes of from the atmosphere.
[2]
Justify a portfolio of two projects that Altavera should prioritize.
[4]
Question 11
A coastal adaptation plan has been proposed for the fictional city of Port Sela. Figure 2 shows the projected storm-surge pathway and selected adaptations.
State whether each of the following adaptations shown in Figure 2 is structural or non-structural: the sea wall and the setback zone.
[2]
Explain how two of the adaptations shown could reduce risk from the projected storm surge.
[2]
Suggest two reasons why the sea wall could result in maladaptation.
[2]
Question 12
The fictional city of Nemer introduced a carbon tax on transport fuels in 2020. Figure 3 shows selected changes following its introduction. All index values equal 100 in 2020.
Figure 3. Selected changes in Nemer following introduction of the transport-fuel carbon tax; all index values are 100 in 2020.
| Year | Carbon tax / US$ per tonne | Petrol sales / index | Public-transport use / index | Policy change |
|---|---|---|---|---|
| 2020 | 0 | 100 | 100 | — |
| 2021 | 20 | 94 | 108 | Bus-service frequency increased |
| 2022 | 40 | 87 | 119 | — |
| 2023 | 60 | 81 | 129 | — |
| 2024 | 80 | 75 | 138 | 90% of low-income households received an equal annual rebate |
Calculate the percentage change in petrol sales between 2020 and 2024.
[2]
Describe two relationships shown in Figure 3.
[2]
Explain how the rebate and the change to bus services could affect the effectiveness and acceptability of the carbon tax.
[3]
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Question 13
The government of the fictional state of Ordan is comparing four climate mitigation projects. Table 1 summarizes their estimated performance.
Table 1: Estimated performance of four climate mitigation projects in Ordan.
| Project | Annual reduction or removal / | Mean cost / USD per tonne | Land required / ha | Storage permanence | Biodiversity effect |
|---|---|---|---|---|---|
| Rewilded native woodland | 30 removed | 35 | 5000 | Medium; wildfire risk | High positive |
| Monoculture afforestation | 45 removed | 25 | 5000 | Medium | Low positive; high water demand |
| Cement-plant capture with geological storage | 120 prevented | 75 | 15 | High; monitoring | Neutral |
| Direct air capture with geological storage | 100 removed | 210 | 20 | High; monitoring | Neutral |
Calculate the estimated annual cost of the direct air capture project in millions of US dollars.
[2]
Distinguish between the mitigation category represented by the cement-plant project and that represented by rewilded native woodland.
[2]
Suggest why Ordan may select a portfolio of projects rather than only the project with the greatest annual emissions reduction.
[3]
Question 14
A government announces that its economy will be carbon neutral by 2050. It plans to use forest offsets to balance emissions remaining in 2050.
Explain two reasons why this announcement alone does not guarantee effective decarbonization.
[4]
Question 15
The figure shows projected global mean surface-temperature change relative to 1850–1900 under five IPCC emissions pathways.
Calculate the difference between the 2081–2100 best estimates for SSP5–8.5 and SSP1–1.9.
[1]
Outline why the pathways overlap substantially during the near term.
[1]
Suggest two reasons why the global mean values shown do not describe the climate impact experienced by every region.
[2]
Question 16
Explain how an emissions trading system can reduce greenhouse gas emissions and why an excessive allocation of permits may limit its effectiveness.
[4]
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Question 17
A city introduces connected charging infrastructure for electric vehicles, as shown in the figure.
Explain why this is a socially embedded mitigation technology and identify one condition that could limit its mitigation benefit.
[4]
Question 18
The three states of Norland, Estara and Belvar are negotiating a regional climate convention. Norland proposes a cross-border carbon tax on selected imports.
Calculate the territorial greenhouse-gas emissions per person for Norland.
[2]
Compare the contribution of exports to the greenhouse-gas emissions of Estara and Belvar.
[2]
Calculate the cross-border carbon tax payable on an Estaran shipment containing 10 000 tonnes of embodied carbon dioxide emissions.
[2]
Explain why state sovereignty can make the regional convention difficult to implement.
[2]
Evaluate the proposed cross-border carbon tax as a way of increasing regional climate cooperation.
[5]
Question 19
The city of Velsen has introduced connected charging stations as part of a smart-city transport programme.
Calculate the percentage reduction in charging demand at 18:00 produced by smart charging.
[2]
Describe how smart charging changes the temporal pattern of electricity demand.
[2]
Explain why the charging system is described as a socially embedded technology.
[3]
Explain two ways the programme may reduce greenhouse-gas emissions.
[2]
Evaluate the effectiveness of Velsen's connected charging programme as a climate mitigation strategy.
[5]
Question 20
The table shows projected global mean surface temperature change under five IPCC emissions scenarios. Temperature change is measured relative to the 1850–1900 mean.
Projected global mean surface temperature change relative to the 1850–1900 mean.
| Scenario | 2020 central / | 2040 central / | 2060 central / | 2080 central / | 2100 central / | 2081–2100 uncertainty range / |
|---|---|---|---|---|---|---|
| 1.1 | 1.4 | 1.4 | 1.4 | 1.4 | ||
| 1.1 | 1.5 | 1.6 | 1.7 | 1.8 | ||
| 1.1 | 1.5 | 1.9 | 2.3 | 2.7 | ||
| 1.1 | 1.6 | 2.2 | 2.9 | 3.6 | ||
| 1.1 | 1.6 | 2.5 | 3.5 | 4.4 |
Calculate the difference between the end-of-century central estimates for SSP5–8.5 and SSP2–4.5.
[1]
Describe the pattern of the five temperature pathways between 2020 and 2100.
[2]
Explain why Figure 4 presents scenarios with uncertainty ranges rather than a single prediction.
[3]
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Question 21
A group of states introduced a cross-border carbon charge on imported cement. The charge was US$50 for each tonne of associated with producing one tonne of cement. Figure 5 shows cement imports in the year before and the year after the charge was introduced.
Calculate the carbon charge applied to one tonne of cement imported from exporter C.
[2]
Analyse the change in the pattern of imports after the carbon charge was introduced.
[2]
Explain one potential contribution and one potential limitation of this cross-border measure for international climate cooperation.
[3]
Question 22
Connected electric-vehicle chargers were introduced in the fictional city of Taris. Drivers could use a mobile application to locate available chargers, while the grid operator could delay charging to periods of lower demand and greater renewable-electricity availability.
Calculate the percentage reduction in electricity demand at 18:00 produced by smart charging.
[2]
Describe how smart charging changes the timing of electricity demand.
[2]
Explain why the mitigation effectiveness of this socially embedded technology depends on more than the charging equipment itself.
[3]
Question 23
Stratospheric aerosol injection has been proposed to reflect more incoming solar radiation and reduce global mean temperature.
Explain two reasons why this geoengineering proposal could not substitute for reducing greenhouse gas emissions.
[4]
Question 24
Explain how free-riding contributes to the tragedy of the commons in international climate management.
[4]
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Question 25
Climate planners in the river-basin state of Kambara use five IPCC emissions scenarios to assess future heat and flood risks.
Projected global mean surface temperature change relative to 1850–1900 under five SSP pathways.
| Scenario | Temperature change in 2020 / °C | Temperature change in 2040 / °C | Temperature change in 2060 / °C | Central temperature change in 2081–2100 / °C | Likely temperature range in 2081–2100 / °C |
|---|---|---|---|---|---|
| SSP1–1.9 | 1.1 | 1.5 | 1.6 | 1.4 | 1.0–1.8 |
| SSP1–2.6 | 1.1 | 1.5 | 1.8 | 1.8 | 1.3–2.4 |
| SSP2–4.5 | 1.1 | 1.6 | 2.1 | 2.7 | 2.1–3.5 |
| SSP3–7.0 | 1.1 | 1.6 | 2.5 | 3.6 | 2.8–4.6 |
| SSP5–8.5 | 1.1 | 1.6 | 2.7 | 4.4 | 3.3–5.7 |
State the projected central estimate of warming in 2081–2100 under SSP3–7.0.
[1]
Calculate the percentage reduction in Kambara's flood-exposed population under SSP2–4.5 achieved by the combined plan compared with no new adaptation.
[2]
Explain why the temperature projections overlap strongly in the near term but separate later in the century.
[3]
Explain why an IPCC emissions scenario should not be interpreted as a prediction.
[2]
Suggest two ways Kambara could make its adaptation plan robust under the range of scenarios.
[2]
Evaluate the use of the scenario data for selecting Kambara's adaptation strategy.
[5]
Question 26
The industrial state of Calidia introduced an emissions trading system in 2022 and a legally binding net-zero greenhouse-gas target for 2050.
Annual emissions-trading cap and permit price in Calidia, 2022–2030.
| Year | Emissions cap / Mt | Permit price / USD per t |
|---|---|---|
| 2022 | 120 | 12 |
| 2023 | 114 | 15 |
| 2024 | 108 | 18 |
| 2025 | 102 | 17 |
| 2026 | 96 | 25 |
| 2027 | 90 | 32 |
| 2028 | 84 | 38 |
| 2029 | 78 | 44 |
| 2030 | 72 | 51 |
Calculate the percentage decrease in the emissions cap between 2022 and 2030.
[2]
Describe two changes in verified sector emissions between 2022 and 2027.
[2]
Explain how the design of Calidia's emissions trading system could reduce emissions at relatively low economic cost.
[3]
Explain one limitation of the voluntary carbon-neutrality goal adopted by Calidia Steel.
[2]
Suggest one way the policy package supports a just transition.
[1]
To what extent has Calidia's combination of economic measures and legislation been effective?
[5]
Question 27
An international scientific panel compared three proposed large-scale interventions in the climate system. Table 2 summarizes its assessment.
Table 2: Assessment of proposed large-scale climate interventions.
| Intervention | Representative response time / years | Primary process | Atmospheric reduced? | Effect on ocean acidification | Major environmental risk | Transboundary governance concern |
|---|---|---|---|---|---|---|
| Stratospheric aerosol injection | 1 | Reflects incoming solar radiation | No | No reduction | Changed regional precipitation; rapid warming if stopped | Very high |
| Ocean fertilization | 10 | Stimulates phytoplankton carbon uptake | Uncertain long-term reduction | Uncertain | Altered food webs; deoxygenation | High |
| BECCS | 25 | Biomass uptake, capture and geological storage | Yes, if net removal occurs | May reduce pressure if net removal occurs | Extensive land and water demand | Medium |
Identify the intervention with the fastest representative response and calculate how many times faster its response is than that of BECCS.
[2]
Compare stratospheric aerosol injection with BECCS as climate mitigation strategies.
[3]
Suggest why international governance would be required before large-scale use of these interventions and why they should not replace emissions reduction.
[3]
Question 28
Distinguish between climate change mitigation and climate change adaptation.
[4]
Explain why a long-term carbon-neutrality target does not, by itself, ensure effective decarbonization of an economy.
[7]
Using named international agreements, evaluate the importance of global cooperation compared with action by individual states in avoiding catastrophic climate change.
[9]
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Question 29
Outline the three main categories of climate change mitigation strategies.
[4]
Explain how combining energy-efficiency measures, renewable energy and ecosystem restoration may provide more effective mitigation than relying on any one of these strategies.
[7]
Using named examples, to what extent should removal of atmospheric be relied upon in national climate mitigation strategies?
[9]
Question 30
Distinguish between structural and non-structural adaptations to climate change.
[4]
Explain how an adaptation planning cycle can reduce the risk of maladaptation.
[7]
Using named examples, discuss whether adaptation plans can protect vulnerable societies from the consequences of climate change.
[9]
Question 31
An international research consortium is comparing large-scale climate interventions. Its governing council includes states with contrasting exposure, resources and economic interests.
Comparison of proposed large-scale climate interventions.
| Intervention | Primary climate effect | Time to effect / years | Annual cost / USD billion | Potential removal / billion tonnes per year | Major stated risks or limitations |
|---|---|---|---|---|---|
| Stratospheric aerosol injection | Reflects incoming solar radiation; does not remove | 1–2 | 18 | None | Altered regional rainfall; rapid warming if stopped |
| Ocean fertilization | Stimulates phytoplankton carbon uptake | 5–15 | 9 | Permanence uncertain | Deoxygenation; altered food webs |
| Bioenergy with carbon capture and storage | Removes and stores | 10–30 | 140 | 2.5 | Competition for land, water and food |
| Direct air capture with geological storage | Removes and stores | 10–25 | 260 | 1.3 | High energy and infrastructure demand |
Distinguish between the primary climate effects of stratospheric aerosol injection and direct air capture.
[2]
Calculate the indicative annual cost per tonne of potential carbon dioxide removal by direct air capture.
[2]
Analyse the changes in stakeholder support for stratospheric aerosol injection after the evidence forum.
[3]
Explain how the proposed interventions illustrate both moral hazard and the tragedy of the commons.
[3]
Suggest one governance requirement for any international trial of stratospheric aerosol injection.
[1]
Evaluate the role geoengineering should play in an international climate strategy.
[5]
Question 32
Distinguish between a carbon tax and an emissions trading system.
[4]
Explain how governmental and non-governmental responses can interact to accelerate a just transition to a low-carbon economy.
[7]
Using named examples, evaluate the effectiveness of combining economic measures, legislation and voluntary industry commitments to reduce greenhouse gas emissions.
[9]
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Question 33
Outline the distinct roles of the IPCC, the UNFCCC and the Conference of the Parties in global climate management.
[4]
Explain how IPCC emissions scenarios can support climate policy despite uncertainty about future conditions.
[7]
Using named examples, to what extent have United Nations processes been effective in producing global action on climate change?
[9]
Question 34
Distinguish between solar radiation modification and greenhouse gas removal as forms of geoengineering.
[4]
Explain why international governance of large-scale geoengineering is affected by the tragedy of the commons and contrasting stakeholder perspectives.
[7]
Using named geoengineering proposals and stakeholder perspectives, evaluate the role that geoengineering should play in climate change mitigation.
[9]
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