Guide

Ocean plastic explained: where it comes from and what helps

Millions of tonnes of plastic enter the world's oceans every year; estimates vary with the method used, but all point to a very large problem. Understanding where it comes from shows where our effort works best.

Where does it come from?

Most ocean plastic starts on land. Litter and poorly managed waste are washed or blown into storm drains, streams and rivers, and carried to the sea. Other sources include fishing gear (lost nets and lines), tyre and textile particles, and spills of plastic pellets used to make products. Rivers - especially in places where waste collection is limited - are major pathways.

Macroplastics and microplastics

Larger items such as bottles, bags and nets can entangle or be swallowed by wildlife. In sunlight and waves they slowly fragment into microplastics (smaller than 5 millimetres), which cannot be cleaned up from the water and have been found from deep trenches to polar ice. Research on their effects on animals and human health is ongoing, which is a reason to reduce them at the source.

The "garbage patches"

Currents gather floating debris into regions such as the Great Pacific Garbage Patch. It is better described as a vast area of scattered fragments than a solid island; much plastic also sinks or lands on shorelines.

What helps most

1. Turn off the tap: reducing single-use plastic, improving waste collection and recycling, and designing products to be reusable matter more than cleaning the sea afterwards.
2. Catch it in rivers: barriers and trash traps in waterways stop plastic before it reaches the ocean.
3. Shoreline cleanups: they remove debris before it fragments and give communities data to support policy.
4. Policy: bans on certain single-use items, deposit-return schemes and producer responsibility rules have shown results.

What you can do this month

• Join or organise a local cleanup (see our cleanup planner).
• Make three plastic swaps and track them on the checklist.
• Put litter in bins; secure your recycling and trash on windy days.
• Support organisations and policies working on prevention.

Figures and effects are active research areas; consult scientific bodies such as UNEP and NOAA for the latest data.