Responses to Climate Change

This lesson examines human responses to climate change, including mitigation strategies, adaptation approaches, international agreements and carbon budgets. It addresses the Edexcel A-Level Geography (9GE0) specification, Topic 6, Enquiry Question: "How are the carbon and water cycles linked to climate change?"

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Mitigation vs Adaptation

Responses to climate change fall into two broad categories:

Response Type	Definition	Aim	Timescale	Examples
Mitigation	Actions to reduce GHG emissions or enhance carbon sinks	Prevent climate change from worsening	Long-term (decades to centuries)	Carbon taxes, renewable energy, CCS, reforestation
Adaptation	Actions to adjust to the effects of climate change	Reduce vulnerability to impacts that are already occurring or inevitable	Short to medium-term	Sea defences, drought-resistant crops, early warning systems

Both mitigation and adaptation are needed — mitigation to limit future warming, and adaptation to cope with the warming that is already locked in.

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Mitigation Strategies

1. Carbon Pricing

Carbon pricing makes emitters pay for the CO₂ they release, creating economic incentives to reduce emissions.

Carbon Tax:

Aspect	Detail
Mechanism	Government sets a price per tonne of CO₂ emitted; emitters pay this tax on their emissions
Advantages	Simple, predictable price signal; revenue can fund green investment or be returned to citizens
Disadvantages	Price may not be high enough to drive change; political resistance; risk of carbon leakage (industries moving to countries without carbon tax)
Examples	Sweden (~$130/tCO₂ — world's highest); UK Carbon Price Support (~£18/tCO₂); Canada ($130/tCO2​—world′shighest);UKCarbonPriceSupport( £18/tCO2​);Canada(65/tCO₂, rising)

Emissions Trading (Cap and Trade):

Aspect	Detail
Mechanism	Government sets a cap on total emissions; allocates or auctions emission permits; companies can trade permits on a market
Advantages	Guarantees emissions reduction (cap is fixed); market determines most efficient reductions; price adjusts to supply/demand
Disadvantages	Price volatility; complex administration; permits may be over-allocated (reducing effectiveness)
Examples	EU Emissions Trading System (EU ETS — world's largest, covering ~40% of EU emissions; price ~€65–90/tCO₂ in 2023); China ETS (launched 2021)

Exam Tip: The EU ETS is an excellent named example for carbon pricing. Note that permit prices were very low in Phase 1 (2005–07, ~€5/tCO₂ due to over-allocation) but have risen substantially in Phase 4 (2021–30, ~€65–90/tCO₂) as caps tightened. This shows that emissions trading can work but requires careful design.

2. Renewable Energy Transition

Transitioning from fossil fuels to renewable energy is the most significant mitigation strategy (see Lesson 8 for detailed coverage). Key targets:

Target	Source	Status
Triple global renewable capacity by 2030	COP28 (2023)	11,000 GW needed; currently ~3,870 GW
Net-zero electricity by 2035 (advanced economies)	IEA Net Zero pathway	Requires massive investment
Phase down unabated coal	Glasgow Climate Pact (COP26, 2021)	Coal still growing in some Asian countries

3. Carbon Capture and Storage (CCS)

CCS involves capturing CO₂ from large point sources (power stations, industrial plants) and storing it permanently underground.

Stage	Process	Status
Capture	CO₂ separated from flue gases using chemical solvents, membranes or oxy-fuel combustion	Proven technology; expensive
Transport	CO₂ compressed and transported via pipeline or ship	Infrastructure developing
Storage	CO₂ injected into deep geological formations (depleted oil/gas fields, saline aquifers)	Operating projects worldwide

CCS Project	Location	Capacity (MtCO₂/yr)	Status
Sleipner	North Sea, Norway	~1.0	Operating since 1996; world's first commercial CCS
Quest	Alberta, Canada	~1.2	Operating since 2015; captures CO₂ from oil sands upgrader
Gorgon	Western Australia	~4.0 (planned)	Under-performing; captured ~2.5 MtCO₂ in first 3 years vs 4.0 planned
Northern Lights	North Sea, Norway	~1.5 (Phase 1)	Under construction; first transport and storage service

Criticism of CCS:

• High cost ($50–120 per tonne CO₂ captured)
• Very limited current deployment (~45 MtCO₂/year captured globally — <0.1% of emissions)
• Risk of leakage from storage sites
• Moral hazard — may be used to justify continued fossil fuel use
• Energy penalty — CCS requires 15–30% of the plant's energy output

4. Nature-Based Solutions

Strategy	Carbon Removal Potential	Co-Benefits
Reforestation/afforestation	3–10 GtCO₂/year by 2050	Biodiversity, flood prevention, water quality
Peatland restoration	0.5–1.0 GtCO₂/year	Biodiversity, flood attenuation, water storage
Soil carbon management	2–5 GtCO₂/year	Improved agricultural yields, water retention
Blue carbon (mangroves, seagrass, salt marshes)	0.5–1.5 GtCO₂/year	Coastal protection, fisheries, biodiversity
Enhanced weathering	2–4 GtCO₂/year (theoretical)	Reduced ocean acidification

Exam Tip: Nature-based solutions are increasingly featured in the Edexcel specification. They offer co-benefits (biodiversity, flood protection, food security) alongside carbon removal, making them politically attractive. However, they cannot substitute for emissions reduction — they are a complement, not a replacement.

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Adaptation Strategies

1. Sea Defences and Coastal Management

Approach	Example	Cost-Effectiveness
Hard engineering (sea walls, groynes, revetments)	Thames Barrier (protects London from tidal surges; operational since 1984; closures increasing)	High cost; effective but may transfer problems
Soft engineering (beach nourishment, managed retreat)	Medmerry, West Sussex — managed realignment created intertidal habitat and natural flood defence	Lower cost; more sustainable
Planned retreat	Communities relocated from eroding coastlines (e.g. Fairbourne, Wales — identified for decommissioning by 2054)	Socially difficult but sometimes necessary

2. Agricultural Adaptation