Oceans as physical systems (circulation, the role in climate and carbon); oceans as contested resources (fisheries, minerals, energy); the geopolitics and governance of marine space; and the synoptic evaluation of ocean management under environmental and political pressure.

What this dot point is asking

This Geographical debate asks you to explain oceans as physical systems (circulation, climate and carbon roles), as contested resources (fisheries, minerals, energy), the pollution and environmental pressures they face, the geopolitics and governance of marine space, and to evaluate synoptically how ocean use and protection can be managed. It is one of five debates from which you study two for Paper 03.

The answer

Oceans as physical systems

Oceans cover most of the planet and do far more than hold water. Surface currents (driven by wind, such as the Gulf Stream) transport heat from the tropics towards the poles, moderating regional climates; deep currents (driven by density) return cold water at depth. The oceans store enormous amounts of heat, buffering atmospheric warming, and absorb roughly a quarter of human carbon dioxide emissions through the solubility and biological pumps, a key carbon sink. They also support marine ecosystems and the biological productivity on which fisheries depend. This makes the ocean system foundational to climate and to the other strands of the debate.

Oceans as contested resources

The oceans are an increasingly contested resource base. Fisheries feed billions and employ millions, but many stocks are overfished beyond sustainable limits, a classic common-pool resource problem. Mineral resources (offshore oil and gas, and prospective deep-sea minerals such as polymetallic nodules) draw growing interest as land reserves deplete and technology advances. Energy from the sea (offshore wind, tidal and wave) is expanding as part of decarbonisation. Rising demand for these finite, shared resources, against a backdrop of unclear ownership beyond national waters, is the root of much contestation, and links directly to food security and energy.

Pollution and environmental pressures

The oceans face mounting environmental pressure. Plastic pollution accumulates in vast quantities, harming marine life and entering food chains. Oil spills and chemical and nutrient runoff (causing eutrophication and dead zones) degrade coastal seas. Ocean acidification, as the sea absorbs carbon dioxide, lowers pH and stresses calcifying organisms such as corals and shellfish, while warming drives coral bleaching and shifts species ranges. These pressures interact with resource use (overfishing reduces ecosystem resilience) and with climate change, so the ocean's capacity to regulate climate and provide resources is itself being eroded, raising the stakes for management.

Geopolitics and governance of marine space

Marine space is geopolitically contested and governed through an evolving framework. The UN Convention on the Law of the Sea (UNCLOS) defines maritime zones: territorial waters (to 12 nautical miles, full sovereignty), the Exclusive Economic Zone (EEZ) (to 200 nautical miles, rights over resources), and the high seas beyond. Disputes arise over overlapping EEZ claims, contested islands and seabed (the South China Sea is the headline example), and Arctic resources as sea ice retreats. Governance also includes regional fisheries management organisations, marine protected areas, and a recent high-seas biodiversity treaty. But enforcement, especially on the high seas, is weak, and powerful states may not ratify or comply, so management remains partial and contested, a strong synoptic link to sovereignty and borders.

Examples in context

Example 1. The South China Sea dispute. Multiple states make overlapping claims to islands, reefs and seabed in the South China Sea, driven by fisheries, oil and gas, and strategic shipping lanes, and contested through EEZ claims and island-building. It is the textbook example of the geopolitics of marine space and the limits of UNCLOS when a powerful state rejects an adverse ruling. It connects oceans directly to power and borders and to trade (shipping chokepoints), making it a rich synoptic case.

Example 2. Overfishing and fisheries governance (for example North Atlantic cod). The collapse of North Atlantic cod stocks after decades of overfishing, despite some management, illustrates the tragedy of the commons and the difficulty of governing shared stocks; some fisheries have since partially recovered under strict quotas, showing governance can work when enforced. Alongside expanding marine protected areas and the high-seas biodiversity treaty, it provides balanced evidence for the assessment of governance effectiveness and links to the future of food.

Try this

Q1. Define an Exclusive Economic Zone. [2 marks]

• Cue. Under UNCLOS, the zone extending to 200 nautical miles from a state's coast within which it has rights over the resources (fishing, minerals, energy), though not full sovereignty.

Q2. Explain why the high seas are difficult to govern. [4 marks]

• Cue. They are a global commons beyond any state's jurisdiction, so no single authority controls them; the tragedy-of-the-commons logic drives overexploitation, and enforcement against illegal fishing and pollution is weak.