The Global Centre for Risk and Innovation (GCRI)
Plastics, excess nutrients, oil, chemicals and untreated sewage reach the sea from rivers, coasts, ships and the air. They harm wildlife, degrade habitats, contaminate seafood and damage tourism and fisheries. This page sets out how marine pollution arises and spreads, how it is measured, and what evidence serves the authorities and industries responsible for reducing it.
GCRI · In development · service level R0
Marine pollution is the introduction of harmful substances or energy into the sea, including plastics, excess nutrients, oil, chemicals and sewage. Most comes from land through rivers and coasts, with ships adding more. It harms wildlife and habitats, creates dead zones and contaminates seafood.
For marine pollution, in GCRI's spatial-intelligence reading, the map opens on marine heat, land cover, true-colour imagery and sea temperature with relief in 3D and a wave forecast chart at the centre, framed on Pacific Island states; every other NASA layer, live feed and forecast waits in the layer list.
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NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
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For marine pollution, in GCRI's spatial-intelligence reading, the map opens on marine heat, land cover, true-colour imagery and sea temperature with relief in 3D and a wave forecast chart at the centre, framed on Pacific Island states; every other NASA layer, live feed and forecast waits in the layer list.Satellite and model products as NASA publishes them, each with its own date; indicators, not assessments of any place; claim ceiling INTEGRATED.
Layers and dates
Contaminants, plastics and ecosystem harm. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Mismanaged waste reaches rivers and coasts and drifts into the sea, where it breaks into microplastics. Fishing gear lost at sea continues to catch wildlife.
Fertiliser and sewage runoff deliver nitrogen and phosphorus that drive algal blooms. Their decay consumes oxygen and creates low-oxygen dead zones.
Oil spills, ballast water, antifouling paints and garbage from ships pollute shipping lanes and ports, with large spills causing acute harm.
Mercury and persistent organic pollutants accumulate in organisms and concentrate up the food chain, affecting wildlife and people who eat seafood.
Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.
| Term | Definition |
|---|---|
| Eutrophication | Excess nutrients in water that cause algal growth and oxygen depletion. |
| Microplastics | Plastic particles smaller than five millimetres, from fragmentation or manufactured small. |
| Ghost gear | Fishing gear lost or abandoned at sea that continues to catch marine life. |
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Index of coastal eutrophication | chlorophyll and nutrient indicators | per assessment | SDG indicator 14.1.1 (a) | ESTIMATED |
| Floating plastic debris density | items per square kilometre | per survey | Surface trawls and models | ESTIMATED |
| Beach litter | items per hundred metres of beach | per survey | Beach litter surveys | OBSERVED |
| Oil spills from tankers | count and tonnes | annual | Spill statistics | REPORTED |
| Hypoxic area | square kilometres | annual | Oxygen surveys | OBSERVED |
| Wastewater safely treated | percent of wastewater flows | per assessment | SDG indicator 6.3.1 | ESTIMATED |
The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.
Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| UNEP SDG 14.1.1 data and Global Environment Monitoring System | Coastal eutrophication and plastic debris indicators | Public, UNEP terms |
| ITOPF oil tanker spill statistics | Tanker spills by size and year | Public, ITOPF terms |
| GESAMP reports | Scientific assessments of marine pollution, including plastics | Public, terms per publication |
| Copernicus Marine Service biogeochemistry products | Chlorophyll, nutrients and oxygen fields | Free, Copernicus Marine licence |
| National beach litter monitoring programmes | Standardised beach litter surveys | Open data where published |
Oceans and Coasts prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Environment ministries and coastal agencies | Which pollution sources to control first | Source assessments; monitoring evidence |
| Wastewater and waste authorities | Where treatment and collection most reduce marine pollution | Pathway and treatment evidence |
| Maritime authorities | How to prevent and respond to ship pollution | Spill statistics; MARPOL implementation |
Excess nutrients from fertilizers and sewage fuel algal blooms; when the algae die and decompose, oxygen is consumed, creating hypoxic zones where many species cannot survive. Warming reduces oxygen solubility and strengthens stratification, so climate change and nutrient pollution reinforce each other. Some blooms produce toxins that close shellfish harvesting and affect human health.
Plastics enter the ocean from rivers, coastlines and fishing gear. Large items entangle and are ingested by wildlife; they fragment into microplastics that are now found throughout the ocean. Persistent chemicals and heavy metals accumulate in sediments and biomagnify up food webs, reaching high concentrations in top predators and in seafood. Oil spills cause acute harm to coastal habitats, birds and fisheries, with effects that can persist for years.
Pollution also travels with hazards. Floods and storms flush contaminants, sewage and debris from land into coastal waters at once, so disaster events can produce pollution pulses that affect fisheries and health after the water recedes.
Chemical analysis and biomonitoring measure concentrations; sampling is costly and patchy.
Satellites detect algal blooms, oil slicks and large debris accumulations, with limits under cloud and at small scales.
Particle-tracking and biogeochemical models simulate where pollutants travel and how they transform.
Limits: microplastic measurement methods are not yet fully harmonized, so results are hard to compare. Source attribution is often uncertain, and long-term health effects of many contaminants remain under study.
The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.