Climate impacts, mitigation and adaptation: WACE Year 12 Earth and Environmental Science
“Analyse the impacts of climate change and evaluate mitigation and adaptation responses”
Climate change affects all four Earth spheres: warming and acidifying oceans, melting ice and rising seas, shifting rainfall and more extreme weather, and stressed ecosystems. Responses fall into two types: mitigation, which reduces the cause by cutting greenhouse gas emissions and increasing carbon sinks, and adaptation, which adjusts to the changes we cannot avoid. Both are needed, because some warming is already locked in.
What this dot point is asking
SCSA wants you to analyse climate change impacts across Earth systems and evaluate mitigation and adaptation. The key conceptual distinction is between attacking the cause (mitigation) and coping with the consequences (adaptation), and a strong answer argues that both are required.
Impacts across the spheres
Climate change ripples through all four Earth systems.
- Atmosphere: rising average temperatures, more frequent and intense heatwaves, droughts and extreme rainfall, and shifting climate zones.
- Hydrosphere: warming and acidifying oceans (as they absorb carbon dioxide), changing ocean currents, and altered rainfall and water availability.
- Cryosphere and sea level: melting glaciers and ice sheets and thermal expansion of seawater raise sea level, threatening coasts.
- Biosphere: species shift their ranges, ecosystems are disrupted, and stresses such as coral bleaching increase.
Western Australia shows several of these: the southwest has experienced a long-term drying trend reducing rainfall and streamflow, and warm-water events have caused coral bleaching and marine ecosystem damage along the coast.
Mitigation and adaptation answer different questions. Mitigation asks how to reduce the cause by cutting emissions and boosting carbon sinks. Adaptation asks how to live with the changes already underway. Because past emissions commit us to some warming, the consensus is that both are needed together.
Mitigation: reducing the cause
Mitigation reduces greenhouse gas concentrations.
- Cutting emissions: shifting from fossil fuels to renewable energy, improving energy efficiency, and reducing emissions from agriculture and industry.
- Enhancing sinks: protecting and restoring forests and other vegetation that absorb carbon dioxide, and developing carbon capture and storage.
- Policy tools: carbon pricing, targets and international agreements coordinate action across countries.
Mitigation tackles the root cause, but its benefits are global and take time, and it requires broad cooperation.
Mitigation: reducing the cause of climate change by cutting emissions or increasing sinks. Adaptation: adjusting to climate change to reduce harm. Ocean acidification: falling ocean pH as it absorbs carbon dioxide. Carbon sink: a reservoir that absorbs more carbon than it releases. Resilience: the ability to cope with and recover from change.
Adaptation: coping with the consequences
Adaptation reduces the harm from changes we cannot prevent.
- Water security: diversifying supply through desalination and recycling, as Perth has done as rainfall declined.
- Coastal protection: sea walls, managed retreat and planning that accounts for rising seas.
- Agriculture and ecosystems: drought-tolerant crops, changed practices, and protecting refuges for vulnerable species.
- Heat and disaster preparedness: planning for heatwaves and more extreme events.
Adaptation protects communities now, but it treats symptoms rather than the cause and has limits if warming becomes severe.
Evaluating the responses
A balanced evaluation concludes that mitigation and adaptation are complementary, not alternatives. Without mitigation, the changes adaptation must cope with grow ever larger and eventually exceed our ability to adapt. Without adaptation, communities suffer from the warming already locked in by past emissions. Effective responses therefore combine ambitious mitigation to limit future change with adaptation to manage the change already underway.
For any strategy, ask whether it reduces the cause or copes with the effect. Building a wind farm or protecting a forest is mitigation (cutting emissions or boosting sinks). Building a desalination plant or a sea wall is adaptation (coping with reduced rainfall or rising seas). Then evaluate its strengths and limits before concluding both types are needed.
- Confusing mitigation and adaptation
- Mitigation reduces the cause; adaptation copes with the effects.
- Treating them as alternatives
- They are complementary; both are needed.
- Listing impacts without naming the sphere
- Analysis questions reward linking each impact to atmosphere, hydrosphere, cryosphere or biosphere.
- Forgetting locked-in warming
- Past emissions commit us to change, which is why adaptation is unavoidable alongside mitigation.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
WACE 2023-style8 marksAnalyse the impacts of climate change on Western Australia's Earth systems, and evaluate the relative roles of mitigation and adaptation in responding to them.Show worked answer →
An 8 mark answer needs sphere-by-sphere WA impacts plus a mitigation-adaptation evaluation.
- Impacts (by sphere)
- Atmosphere: a long-term drying trend has cut southwest WA rainfall, with more heatwaves. Hydrosphere: reduced rainfall lowers streamflow and groundwater recharge (Gnangara Mound decline), and warming, acidifying oceans plus marine heatwaves have caused coral bleaching along the WA coast. Cryosphere/sea level: thermal expansion and melting ice raise sea level, threatening low-lying coast and infrastructure. Biosphere: species ranges shift and ecosystems are stressed.
- Mitigation
- Cutting emissions (renewables, abundant WA solar and wind, efficiency, protecting vegetation sinks, carbon pricing and the Paris Agreement) tackles the cause, but benefits are global and slow and need broad cooperation.
- Adaptation
- Coping with locked-in change: desalination and water recycling for supply (already used in Perth), coastal defences and planning, drought-tolerant crops, heatwave preparedness.
- Evaluation
- They are complementary, not alternatives. Without mitigation, the change adaptation must handle keeps growing and may exceed adaptive limits; without adaptation, communities suffer warming already committed by past emissions. Effective response combines ambitious mitigation with adaptation.
Markers reward WA-specific impacts tied to spheres and a balanced evaluation concluding both responses are needed.
WACE 2021-style6 marksDistinguish between mitigation and adaptation, and for each of a wind farm, a desalination plant and reforestation, state which type of response it is and justify your choice.Show worked answer →
A 6 mark answer needs the distinction and correct, justified classification of each example.
- Distinction
- Mitigation reduces the cause of climate change by cutting greenhouse gas emissions or increasing carbon sinks. Adaptation adjusts to climate impacts already occurring to reduce harm.
- Wind farm: mitigation
- It generates electricity without burning fossil fuels, cutting carbon dioxide emissions, so it reduces the cause.
- Desalination plant: adaptation
- It secures water supply as rainfall and recharge decline (as in Perth), coping with a consequence of climate change rather than reducing emissions. (It can even increase emissions if powered by fossil fuels.)
- Reforestation: mitigation
- Growing forests absorb carbon dioxide, increasing the carbon sink, so it reduces atmospheric greenhouse gas, the cause.
Markers reward the cause-versus-effect distinction and correct classification with justification (wind and trees act on emissions/sinks; desalination copes with reduced water).