The global carbon cycle as a system, the link between carbon, energy security and climate change, and management responses.

What this dot point is asking

WJEC wants you to describe the global carbon cycle and its stores and fluxes, explain how it links to energy security and climate change, and evaluate the strategies and governance used to manage carbon, with located examples.

The answer

The global carbon cycle

The largest store by far is the lithosphere (sedimentary rocks and fossil fuels); the oceans hold a large, fast-exchanging store, while the atmosphere holds a small but climatically crucial share. Fluxes include photosynthesis (uptake by plants), respiration and decomposition (release), ocean-atmosphere exchange, and combustion and volcanic activity. Natural carbon sinks include forests, soils, peatlands and the oceans, which between them absorb roughly half of human carbon emissions, slowing but not stopping the atmospheric rise.

Carbon, energy and climate

Energy security is reliable, affordable, sustainable access to energy. Heavy reliance on fossil fuels secures supply in the short term but raises emissions; shifting to low-carbon sources improves the carbon balance but raises questions of cost, intermittency and supply, so energy security and decarbonisation can be in tension. The 2022 energy price shock following the invasion of Ukraine showed how fossil-fuel dependence threatens both security and affordability, strengthening the case for domestic low-carbon energy.

Managing carbon emissions

Mitigation reduces emissions: renewables (onshore and offshore wind, solar, and tidal, including Wales's strong wind resource and proposed tidal lagoons in Swansea Bay), nuclear (Wylfa in Anglesey, Hinkley Point C in Somerset), carbon capture and storage, afforestation and improved energy efficiency. Adaptation manages unavoidable impacts (flood defence, drought-resistant crops). Managing carbon also protects natural sinks such as forests and the Welsh peatlands, whose restoration locks carbon away.

Governance of carbon

Carbon governance is multi-scalar: international agreements such as the Paris Agreement (2015) commit countries to limiting warming to well below $2$ degrees Celsius; national governments set legally binding goals (the UK's net-zero by 2050 target under the Climate Change Act, and Welsh climate legislation); and local actors and businesses act on the ground. Governance is uneven and contested, balancing economic growth, energy security and emissions reduction.

Examples in context

Example 1. Low-carbon energy in Wales. Wales has a strong renewable resource: extensive onshore and offshore wind, and one of the largest tidal ranges in the world in the Severn Estuary, which underpinned the proposed Swansea Bay tidal lagoon. The historic Wylfa nuclear site on Anglesey has been considered for new nuclear capacity. Together these show how a region can pursue both decarbonisation and energy security by replacing fossil fuels with domestic low-carbon supply, while the cancelled Swansea lagoon illustrates the cost and political barriers that can stall such projects.

Example 2. The Paris Agreement and net-zero targets. The 2015 Paris Agreement committed nearly $200$ countries to limit warming to well below $2$ degrees Celsius, pursuing $1.5$ degrees, through nationally determined contributions. The UK translated this into a legally binding net-zero by 2050 target, and Wales has set its own ambitious climate goals. The case shows multi-scalar governance from global treaty to national law, and also its limits: pledges are often voluntary and uneven, so emissions cuts have so far fallen short of what the targets require, a key point for any assessment.

Try this

Q1. Name two natural processes that transfer carbon between stores. [2 marks]

• Cue. Any two of photosynthesis, respiration, decomposition, combustion or ocean-atmosphere exchange.

Q2. Explain how burning fossil fuels links energy use to the carbon cycle. [3 marks]

• Cue. Combustion transfers carbon from the lithosphere store to the atmosphere as carbon dioxide, enhancing the greenhouse effect and driving climate change.