Plastic waste and agricultural runoff are responsible for most marine pollution
About 80% of marine pollution comes from land and is always caused by humans. The two main causes of land-based ocean pollution are agriculture and the (absence of) waste management. More specifically, fertilizers and pesticides used in agriculture, and all kinds of man-made waste, private or industrial, that end up in the coastal or marine environment. The wastes are mostly composed of
non-degradable materials, such as plastics. Most plastics enter rivers via stormwater runoff and reach from there into the oceans. Another important factor is littering along coasts and beaches, especially in areas with heavy tourism. Plastic pollution from land-based sources is particularly bad in Southeast Asia and China.
Discarded and lost fishing nets are a major source of plastic pollution
An estimated 20% of ocean pollution comes from marine activities. These are mainly discarded or lost fishing nets, as well as other plastic debris from fishing, maritime transport, or oil platforms. The International Convention for the Prevention of Pollution from Ships (MARPOL) has banned the dumping of plastic waste, but there is still a lot of legacy pollution.
Every minute, two garbage truck loads of plastic are dumped into the ocean
Determining the amounts of plastic in oceans is complicated. Various assumptions lead to large uncertainties. One calculation, based on data from 2010, estimates that between 5 and 13 million tons of plastic enter the oceans each year. This is equivalent to about two garbage trucks dumping plastic into the oceans every minute. This also means that there are already several hundred million tons of plastic in the ocean today, or about 50 kg of plastic for every person alive today. However, every piece of plastic in the oceans is one too many.
Microplastics also come from synthetic clothing and personal care products
Microplastics are generally defined as plastic particles between 0.33 and five millimeters in size. They come from a variety of sources, such as pre-produced pellets and powders, or fragments that have been broken down from larger plastic pieces. Even some personal care products contain microplastics to create an exfoliating effect. Furthermore, synthetic clothing, such as sportswear, can release up to 2000 plastic fibers in a single wash. Most water treatment plants cannot remove these fibers. The water with the fibers is released from the treatment plant and takes its way down the river to the oceans.
No state feels responsible for removing waste from the oceans
Once plastic pieces reach the ocean, they are caught by the ocean currents and drift out to the open sea. A garbage patch is formed where two currents meet and plastic debris is concentrated in the gyre. Currently, five major garbage areas are known to exist in the Atlantic, Pacific and Indian Oceans. These accumulation zones are located outside of national jurisdictions. Therefore, independent private initiatives and intergovernmental bodies are the only entities that can address the problems in these locations.
Ocean pollution is also problematic for human health and wellbeing
The risks of plastic pollution are many. Because plastics are persistent, all impacts of plastic pollution are long-term in nature. Impact examples range from physical, chemical, and biological to economic. Tens of thousands of marine organisms have already become entangled in or have ingested plastics. Experts predict that by 2050, 99% of seabird species will have ingested plastic, which in turn can lead to starvation. Plastics are also full of chemicals that can accumulate in the food chain and in the fish we eat. The effects of such long-lived organic pollutants have not been adequately studied. Invasive species, such as mussels, can grow on plastic debris and are transported over long distances. Finally, fishing, shipping and tourism also suffer when ecosystems are impacted and can no longer provide their services.
Only radical change can stop plastic pollution
Global plastic production is still growing by about 4% per year. The only solution to stop this requires a radical change in both industry and consumers. Industry must reduce the use of plastic packaging, and consumers must stop using single-use plastic.
To successfully achieve this change in the long term, everyone, but children and young people in particular, need to be educated about the risks of plastic pollution and learn about alternatives. While participatory collection campaigns along rivers and coasts remove relatively little litter, the educational value of these campaigns is very high.
Improving waste management capacity in a few rapidly developing countries is an important intermediate step to stop plastic pollution. These countries currently do not have the appropriate infrastructure to collect and manage the volumes of waste they generate. They need to improve their collection, sorting and treatment facilities.
Seven ways of reducing ocean pollution
As a consumer, you can take some steps yourself and encourage others to join in. Depending on where you live, some of the following steps are more or less practical:
- Reduce your use of single-use plastics (e.g., food packaging)
- Check if your personal care products contain microplastics, and if so, switch to other products
- Wash your synthetic clothing as little as possible, and if you do, wash them in a laundry bag that retains microfibers
- Always dispose of your trash in an appropriate manner
- Reuse and recycle whenever possible
- Organize or participate in a riverbank, land or beach cleanup
- Lobby your (local) government for policies to reduce plastic use in industry and consumers