You are viewing a free preview of this lesson.
Subscribe to unlock all 10 lessons in this course and every other course on LearningBro.
Spec mapping: AQA 7037, Paper 1 (Physical), §3.1.1 — the human role in the carbon cycle and strategies to manage carbon at local, national and global scales, including mitigation and adaptation. This depth lesson assumes the source/sink and feedback understanding built earlier and evaluates the full management portfolio — CCS/BECCS, afforestation and REDD+, carbon pricing (tax vs trading), the renewable transition, and net-zero/Paris governance — through the lens of effectiveness, scalability, cost, permanence and equity. AOs exercised: AO1 (precise mechanisms, scheme data, policy detail), AO2 (evaluating trade-offs and the mitigation–adaptation balance), AO3 (manipulating cost-per-tonne, sequestration-potential and emissions-gap figures). Synoptic links run to Global systems (climate governance, COP, equity), Energy/resource security, and Ecosystems (nature-based solutions).
Managing carbon is the defining environmental challenge of the century. Strategies span a spectrum from mitigation (reducing emissions or removing CO₂) to adaptation (living with unavoidable change), and from technological fixes to market mechanisms and nature-based solutions. The depth treatment requires not a catalogue but a comparative evaluation: every strategy must be weighed on how much it can deliver, how fast, at what cost, how permanently, and with what distributional consequences — because no single measure is sufficient and the credibility of "net zero" depends on the mix.
| Mitigation | Adaptation | |
|---|---|---|
| Aim | Tackle the cause (cut emissions / remove CO₂) | Manage the consequences of warming |
| Examples | Renewables, CCS, afforestation, carbon pricing | Flood defences, drought-resistant crops, managed retreat |
| Scale of benefit | Global (one tonne not emitted helps everyone) | Local/regional |
| Timescale | Slow to show climate benefit (committed warming) | Faster local payoff |
Because of committed warming (the deep-ocean lag and long CO₂ perturbation lifetime from earlier lessons), both are now essential — mitigation to limit how bad it gets, adaptation to cope with what is already locked in. Framing answers around this complementarity is a reliable AO2 discriminator.
CCS has three stages:
Current status (mid-2020s). Around 40+ commercial facilities capture on the order of ~45–50 MtCO₂/yr — well under 0.5% of global emissions. Sleipner (Norway, since 1996) has stored >20 MtCO₂ in a North Sea saline aquifer; Gorgon (Western Australia) targets ~4 MtCO₂/yr but has underperformed.
BECCS (Bioenergy with CCS) couples biomass energy with capture to deliver negative emissions (plants absorb CO₂; combustion energy is used; the CO₂ is then stored). Most IPCC 1.5 °C pathways rely heavily on BECCS — controversially, given its land and water demands.
| Strengths | Limitations |
|---|---|
| Cuts emissions from existing fossil and industrial plant | Expensive (~£/US$50–100+ per tCO₂) |
| Geological storage potentially very secure (Mt-scale, decades proven) | Energy penalty of ~10–40% (more fuel burned per unit output) |
| BECCS offers negative emissions | Storage is geographically constrained |
| May be the only option for hard-to-abate cement and steel | Risk of prolonging fossil dependence ("moral hazard") |
Key evaluation: At ~45 MtCO₂/yr against ~37 GtCO₂/yr of emissions, CCS is currently ~0.1% of the problem. It is plausibly essential for residual industrial emissions, but it is not a substitute for cutting emissions — a point top answers make explicitly.
Afforestation = planting where there was no recent forest; reforestation = restoring recently cleared forest.
Sequestration potential:
Limitations: land competition with food (a food-security trade-off); non-permanence (fire, pest, disease, future clearance re-release the carbon); saturation (old-growth forest is near carbon-neutral); biodiversity-poor monocultures; and boreal albedo effects (dark conifers over snow can warm locally, partly offsetting the carbon benefit). Trees also take decades to reach full storage.
REDD+ (Reducing Emissions from Deforestation and forest Degradation, plus conservation, sustainable management and stock enhancement) pays developing countries performance-based sums for verified reductions in deforestation below a baseline, funded by developed nations and carbon markets — making a standing forest worth more than a cleared one.
| Strengths | Limitations |
|---|---|
| Targets ~10% of global CO₂ (land-use change) | Baselines are hard to set credibly |
| Co-benefits: biodiversity, Indigenous rights, watersheds | Monitoring/verification demanding (satellite + ground-truth) |
| Cost-effective (~US$5–15/tCO₂ avoided) | Leakage — clearing displaced elsewhere |
| Engages the Global South in climate action | Sovereignty concerns; "carbon colonialism" critique; permanence risk |
Government sets a cap, issues/auctions allowances, and lets firms trade: under-emitters sell surplus permits, over-emitters buy. The cap tightens over time, driving emissions down while the market finds the cheapest cuts.
The EU Emissions Trading System (EU ETS) — the world's largest carbon market, covering ~40% of EU greenhouse-gas emissions (power, heavy industry, intra-EU aviation). Launched 2005, now Phase IV (2021–2030). The price climbed from a depressed €5–8/tCO₂ to roughly €60–100/tCO₂ in 2023–24 — high enough to bite. Covered-sector emissions have fallen substantially since 2005, though causation is shared with gas-to-renewables switching and other policies.
Weaknesses: early over-allocation collapsed the price; price volatility deters investment; carbon leakage (industry relocating to unpriced jurisdictions); and administrative complexity.
A carbon tax sets the price directly (per tCO₂e), letting the market determine the quantity.
| Carbon tax | Cap-and-trade |
|---|---|
| Price certain; emissions quantity uncertain | Quantity certain (capped); price uncertain |
| Simple to administer | Complex market to design and police |
| Revenue to government (can be recycled/redistributed) | Revenue via the market/auctions |
| No over-allocation risk | Over-allocation can collapse the price |
Decarbonising energy is the single largest mitigation lever, because energy use dominates emissions.
| Technology | Approx. global electricity share (2023) | Cost trend |
|---|---|---|
| Hydropower | ~15% | Mature; limited new large-scale sites |
| Wind (on+offshore) | ~7–8% | Onshore cost down ~70% since 2010 |
| Nuclear | ~9% | Stable cost; long build; low-carbon, firm |
| Solar PV | ~5–6% | Cost down ~90% since 2010 |
| Bioenergy | ~2–3% | Sustainability varies with feedstock |
Net zero = residual emissions balanced by equivalent removals.
| Country/region | Net-zero year | Status |
|---|---|---|
| UK | 2050 | Legally binding (Climate Change Act 2008, amended 2019) |
| EU | 2050 | Legally binding (European Climate Law 2021) |
| USA | 2050 | Executive commitment |
| China | 2060 | Policy commitment |
| India | 2070 | Policy commitment |
Critical evaluation: Net-zero pledges are only credible with binding interim targets and near-term policy. Over-reliance on future removals (BECCS, afforestation, direct air capture) to offset present emissions risks "mitigation deterrence" — using uncertain future negative emissions to justify delay now. Distinguishing credible from aspirational net zero is a key AO2 move.
Compare three options on cost per tonne and scale.
| Strategy | Indicative cost (US$/tCO₂) | Plausible scale (GtCO₂/yr) |
|---|---|---|
| REDD+ (avoided deforestation) | 5–15 | ~1–3 |
| Afforestation | 10–50 | ~1–3 |
| CCS/BECCS | 50–100+ | <0.1 today; ~1–5 long-term (contested) |
Manipulate. If the emissions gap to a 1.5 °C-consistent 2030 pathway is ~23 GtCO₂/yr (UNEP Emissions Gap order of magnitude), and the cheapest land-based options realistically deliver only ~3–5 GtCO₂/yr, then removals/offsets could close at most:
235×100≈22%
of the gap — meaning at least ~78% must come from cutting emissions (energy transition, efficiency), not from removals.
Explain and evaluate. Cheap options (REDD+) are not very scalable and risk leakage and reversal; scalable options (CCS) are expensive and immature. The calculation shows mathematically why removals cannot substitute for mitigation and why a portfolio is unavoidable — but the cost and scale figures are uncertain ranges, and cost-effectiveness ignores co-benefits (REDD+ biodiversity) and permanence (forests can burn; geological CCS is more durable). Quoting the ranges as indicative and weighing scale against cost and permanence is what earns full AO3 credit.
The specification asks for management at local, national and global scales, so a national case study is valuable. The UK offers a relatively credible example of national decarbonisation.
The UK case lets a candidate evaluate credibility: a binding legal framework and real power-sector success, set against the much steeper challenge of the remaining sectors and the leakage caveat — exactly the kind of grounded, two-sided national assessment the top bands reward.
Because committed warming makes some change unavoidable, adaptation is an essential complement to mitigation, and strong answers give it due weight rather than treating mitigation as the whole story.
| Sector | Adaptation strategy | Example |
|---|---|---|
| Coasts | Hard defences, managed realignment, "making space for water" | Thames Barrier upgrades; UK coastal realignment schemes |
| Water | Storage, transfers, demand management, reuse | Reservoirs, NEWater, drought planning (link to water lesson) |
| Agriculture | Drought- and heat-tolerant crops, changed planting calendars, irrigation efficiency | Drought-resistant maize varieties in sub-Saharan Africa |
| Cities | Heat action plans, green/blue infrastructure, "sponge cities" | Urban tree planting; permeable surfaces and SuDS |
| Health | Early-warning systems for heatwaves and disease | European heat-health warning systems |
The crucial AO2 framing is that mitigation and adaptation address different parts of the same problem — mitigation limits the amount of future change (a global benefit, slow to materialise); adaptation reduces vulnerability to the change already locked in (a local benefit, faster to act). There is also an equity dimension: the countries least responsible for emissions are often most exposed and least able to afford adaptation, which is why climate finance (e.g. the contested "loss and damage" fund agreed at COP27/COP28) has become central to global negotiations — a direct synoptic link to Global systems and development.
Offsetting — paying for emissions reductions or removals elsewhere to "cancel" one's own emissions — underpins many corporate and national net-zero claims, but its integrity is a live and examinable controversy.
Subscribe to continue reading
Get full access to this lesson and all 10 lessons in this course.