Carbon Management Strategies

Managing carbon emissions is the defining environmental challenge of the 21st century. A wide range of strategies exist, from technological solutions like carbon capture and storage (CCS) to market-based mechanisms like carbon trading. For AQA A-Level Geography, the ability to evaluate these strategies — considering their effectiveness, feasibility, cost, and limitations — is essential for achieving high marks in extended response questions.

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Carbon Capture and Storage (CCS)

How CCS Works

CCS involves three stages:

1. Capture: CO₂ is separated from flue gases at power stations or industrial facilities. Three main capture methods exist:

   • Post-combustion: CO₂ is removed from exhaust gases after burning fossil fuels using chemical solvents (typically amines). This is the most developed technology.
   • Pre-combustion: Fuel is partially oxidised to produce a hydrogen/CO₂ mix; CO₂ is separated before combustion. The hydrogen is then burned for energy.
   • Oxy-fuel combustion: Fuel is burned in pure oxygen rather than air, producing a flue gas that is almost entirely CO₂ and water vapour, making capture straightforward.

2. Transport: Captured CO₂ is compressed and transported via pipeline or ship to a storage site.

3. Storage: CO₂ is injected into deep geological formations:

   • Depleted oil and gas reservoirs (proven containment over millions of years).
   • Deep saline aquifers (porous rock formations filled with brine; the largest potential storage capacity).
   • Unmineable coal seams (CO₂ can displace methane, which can be captured for energy — Enhanced Coal Bed Methane, ECBM).

Current Status

• As of 2024, there are approximately 40 commercial CCS facilities worldwide, capturing roughly 45 MtCO₂/yr — less than 0.5% of global emissions.
• The largest operational facility is the Gorgon Project in Western Australia, designed to capture and store 4 MtCO₂/yr (though actual performance has been below target).
• The Sleipner Project in Norway (operational since 1996) has stored over 20 MtCO₂ in a deep saline aquifer beneath the North Sea.

Evaluation

Strengths	Limitations
Can reduce emissions from existing fossil fuel infrastructure	Very expensive (£50–100+ per tonne of CO₂ captured)
Deep geological storage is potentially very secure	Energy penalty: CCS reduces power station efficiency by 10–40%
Can be combined with bioenergy (BECCS) for negative emissions	Storage capacity is geographically limited
Proven technology at small scale	Public acceptance concerns about CO₂ leakage
May be necessary for hard-to-decarbonise sectors (cement, steel)	Risk of prolonging fossil fuel dependence

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Afforestation and Reforestation

Definitions

• Afforestation: Planting trees on land that has not been forested for a long time (or ever, in human memory).
• Reforestation: Re-establishing forest on land that was recently deforested.

Carbon Sequestration Potential

• A mature temperate forest can sequester approximately 5–10 tonnes of CO₂ per hectare per year (tCO₂/ha/yr).
• Tropical forests can sequester 10–20 tCO₂/ha/yr in their early growth phase.
• Global estimates suggest that restoring degraded forests and planting new forests could remove 3.6–10 GtCO₂/yr — though the higher estimates are contested (Bastin et al., 2019 vs Veldman et al., 2019).

Limitations

• Land competition: Large-scale afforestation competes with agriculture for land, potentially threatening food security.
• Permanence: Forests can be lost to fire, disease, storms, or future land use change, releasing stored carbon.
• Saturation: Carbon uptake slows as forests mature; old-growth forests are approximately carbon-neutral.
• Monoculture plantations provide less biodiversity value than native woodland and may be more vulnerable to pests and disease.
• Albedo effects: In boreal regions, dark conifer forests absorb more solar radiation than snow-covered ground, potentially offsetting some of the cooling benefit of carbon sequestration.
• Timescale: Trees take decades to reach full carbon storage capacity.

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REDD+ (Reducing Emissions from Deforestation and Forest Degradation)

What Is REDD+?

REDD+ is a UN-backed framework that provides financial incentives for developing countries to reduce deforestation and forest degradation. The "+" indicates additional activities: sustainable forest management, conservation, and enhancement of forest carbon stocks.

How It Works

• Developing countries receive performance-based payments for verified reductions in deforestation below a baseline.
• Funding comes from developed countries, international organisations, and carbon markets.
• Payments value the carbon stored in standing forests, making conservation economically competitive with logging or agriculture.

Case Study: Brazil's Amazon Fund

• Established in 2008, funded primarily by Norway and Germany.
• Between 2004 and 2012, Brazil reduced Amazon deforestation by approximately 80% (from ~27,800 km² to ~4,570 km²/yr).
• Deforestation rates subsequently increased again between 2013 and 2022 under changing political priorities, but declined sharply in 2023 following renewed enforcement.
• The Amazon Fund has received over $3.4 billion in pledges.

Evaluation

Strengths	Limitations
Addresses a major emissions source (~10% of global CO₂)	Difficult to establish accurate baselines
Co-benefits: biodiversity, indigenous rights, watershed protection	Monitoring and verification are challenging (satellite + ground-truth)
Can be cost-effective ($5–15/tCO₂ avoided)	Risk of "leakage" — deforestation displaced to unprotected areas
Engages developing countries in climate action	Sovereignty concerns; risk of "carbon colonialism"
Provides income to forest communities	Corruption and governance challenges in some recipient countries

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Carbon Trading and Cap-and-Trade

Cap-and-Trade Systems