Plastic pollution in the ocean: What you need to know

More than two-thirds of Earth’s surface is covered in water, so, given our propensity for plastic, it feels almost inevitable that we’d create plastic pollution in the ocean. From unintentional debris runoff from rivers and waterways to illegal dumping, the big blue deep is being consistently polluted by waste. Here’s what you need to know about the causes and consequences of plastic in the ocean. 

Why is plastic bad for the ocean? 

We’ll get into the dirty details later on, but in a nutshell: Pollution in the deep is a problem that permeates nearly all aspects of life on Earth. Plastic waste is bad everywhere, but when it finds its way into the ocean, it can wreak all kinds of new havoc on marine ecosystems, the climate, and our own health. Ocean plastic infiltrates the diets of animals, wends its way into our tap water, and may even worsen the impacts of the climate crisis.

How much plastic enters the ocean

While estimates on the exact total of plastic that enters the ocean differ, one report from the United Nations Environment Programme estimates that 11 million tons of plastic end up there each year—or about 3% the approximately 300 million tons of plastic waste produced annually.¹ Plastic waste began littering the ocean in a significant way in the 1960s with a rise in the materials’ production and use. The first record of ocean plastic waste was logged in 1957.²

Where does plastic in the ocean come from?

Just as there are different types of plastic in the products we use every day, there are a  multitude of ways that plastic can end up in the ocean. Production, use, and disposal all contribute to the crisis. 

Littering and improper recycling 

Currently, the majority of plastic pollution is created by improper or inadequate waste management. An estimated 22% of plastic waste is not collected or disposed of properly or becomes litter, according to the Organisation for Economic Co-operation and Development (OECD).³ When this happens, that waste can be blown by the wind or carried by rainwater into oceans and waterways. This is compounded by illegal waste dumping, which introduces significant plastic waste directly and intentionally into the ocean.⁴

Around 11 million tons of plastic end up in the ocean each year—or about 3% the approximately 300 million tons of plastic waste produced annually.

That 22% also includes the mis-handling of plastic by both individuals and companies. This includes what we think of as “littering,” where individuals discard their waste incorrectly in the environment around them. “Improper recycling” is also quite commonplace. This happens when individuals or corporations fail to recycle the right plastic in the right way, which can cause issues at plants and result in the materials becoming waste. 

The fishing industry

Plastic waste can also enter the ocean through the fishing industry. About 640,000 tons of waste from things like nets, lines, and traps end up in the water.⁵ In fact, according to a 2022 report from The Ocean Cleanup, fishing activities are responsible for about 80% of the plastic in the Great Pacific Garbage Patch, a clump of debris in the North Pacific ocean that remains the largest collection of ocean plastic in the world.⁶

Industrial and commercial waste

While individual personal waste contributes to the problem of ocean plastic, industrial and commercial plastic production happens on a much larger scale. And, as referenced in the Plastic Waste Makers Index annual report by Minderoo Foundation and consultancy Wood Mackenzie, just 20 companies, including ExxonMobil, Sinopec, and Dow, are responsible for over half of single-use “throwaway” plastic waste items globally. ⁷   

Microplastics 

In addition to the large plastic debris, or macroplastics, that clutters the oceans, microplastics permeate our planet’s waters. Microplastics, or tiny pieces of plastic less than 5 millimeters in length, come from many sources. Cosmetic microbeads found in glitters and cleansers can enter the ocean when they’re washed away by rain or down your sink’s drain. There are also “secondary microplastics,” which are the small pieces of plastic that come off of car tires or synthetic fabrics like microfleece. And other microplastics come from larger plastic pieces already in the ocean that have degraded over time. Microplastics make up about 8% of the Great Pacific Garbage Patch. 

Ocean pollution by country 

Plastic ocean pollution is a global issue, given how materials move around the world. The Philippines contribute the most plastic ocean waste by far, with more than 356,000 metric tons annually, according to a 2021 study.⁸ Other major contributors include India, China, and Malaysia. Though it is important to note that the U.S. and European nations often ship their plastic waste to these countries. 

How does plastic enter the ocean?

Plastic waste on land can easily end up as plastic waste in the ocean, causing additional problems for humans and wildlife around the world. There are multiple ways that plastic can end up in the water.

Land-based sources

Land-based activities are the biggest source of plastic ocean pollution, according to the United Nations. In fact, the U.N. estimates that as much as 80% of all marine pollution comes from land-based sources. 

Some of the main sources of this pollution are waste disposal close to coasts or waterways, littering near bodies of water, and the fishing industry. Poor waste management is also a prime factor: Plastic waste can leak out into the environment from landfills and incineration facilities, for example.⁹

Rivers and other waterways

Rivers are a major carrier of plastics pollution. A study from 2021 found that 1,000 rivers around the world contribute almost 80% of ocean plastic emissions.¹⁰ When it rains, and especially when it floods and rivers overflow, plastic ends up in the water and eventually in oceans, though some of this material does get stuck within the riverbed.¹¹ During heavy rain, plastic pollution may increase up to tenfold.¹² 

Ocean current and gyres

Gyres, which are large systems of swirling currents, can collect plastic in our oceans. There are five gyres across the globe, and while they circulate water around the world’s oceans, they also pull in pollution from coastal areas. The most famous example of this is the Great Pacific Garbage Patch, which is found in the North Pacific Gyre. The patch is a giant collection of primarily plastic debris that the gyre has concentrated into a patch in the North Pacific Ocean. Scientists first discovered garbage in this region of the ocean on an expedition in 1972; the researchers were startled to see roughly 53 pieces of human-made garbage, more than half of which they estimated to be plastic, according to a Science News report. There are now thought to be about 1.8 trillion pieces of trash, mostly plastic, in the patch. 

Impacts of plastic pollution on marine life

Plastic pollution poses a lot of risks for marine life—and the dangers of ingestion, physical entrapment, and chemical pollution are especially worrisome for the endangered species that call our oceans home. Plus, as plastic breaks down into smaller and smaller pieces, our understanding of risk can change. 

Fishing activities are responsible for about 80% of the plastic in the Great Pacific Garbage Patch

Scientists have confirmed that species around the world—including birds, fish, marine mammals like whales and dolphins, sea turtles, plankton, and shellfish—have all ingested plastic. Marine animals also ingest tiny, nearly impossible-to-detect microplastics. Baleen whales and fishes, along with passive feeding animals like clams and krill, filter their food from water or soil/sand might accidentally ingest microplastics as they eat. 

Effects on marine biodiversity

Thousands of marine animals are killed every year after ingesting plastic or getting caught in plastic debris, according to the Center for Biological Diversity. An estimated 700 different species, including endangered wildlife like Hawaiian Monk Seals and Pacific loggerhead sea turtles, are harmed by plastic pollution. 

Disruption of marine ecosystems

As individual marine organisms ingest plastics, pollution can move through the food chain and impact entire ecosystems. For example, if a very small organism ingests microplastics—or the toxic chemicals leached from those plastics into the water—and it becomes another larger organism’s breakfast, the contamination can move up the food chain. In fact, microplastics have even been detected in seafood ingested by humans.¹³ Microplastics can also embed themselves in the seafloor, where they accumulate and linger.¹⁴ 

Water pollution and chemical contamination

Marine animals can and do ingest pieces of plastic, big and small, but they also inadvertently absorb toxic chemicals in the water that leach out of plastic waste. Scientists have found that these chemicals have even been known to mimic the odor of different food, luring wildlife to get even closer.¹⁵ Plastics can be imbued with UV protectants, colors, flame retardants, and other chemical additives—all of which can leach into the water over time. Not only do plastics often contain harmful chemicals on their own, when exposed to seawater over long periods of time, contamination can accumulate.¹⁶

Effects on coral reefs

In addition to the stresses and impacts that climate change has on coral reefs, plastic pollution also causes significant harm.¹⁷ As plastic ingested by small organisms can move through a food chain, plastic contamination also spreads through reef food webs, damaging the structure of reefs. It is even linked to an increase in disease transmission in coral reefs.

Altered nutrient cycles and oxygen depletion

Increased plastic pollution may also alter the ocean’s natural carbon cycle. The surface of the ocean traps and absorbs atmospheric carbon dioxide and oxygen, and these gasses are then absorbed by ocean-dwelling phytoplankton that feed ecosystems. These tiny creatures then poop, which eventually embeds the carbon at the bottom of the sea. According to Client Earth, plastic makes those droppings more buoyant, and therefore a considerably less useful carbon sink.

Plastic could also be responsible for an extreme loss of ocean oxygen, which can become a life-or-death problem for creatures living in the ocean, according to a 2021 study.¹⁸ The scientists found that zooplankton are ingesting microplastics instead of their usual food sources like oxygen and carbon dioxide-absorbing phytoplankton. This dietary shift could result in increased algal blooms, which also disrupt ocean oxygen levels. Ocean oxygen levels are expected to drop 3-4% by the end of the century, and the volume of oxygen-free ocean zones has quadrupled since the 1960s, according to the International Union for Conservation of Nature.

Impacts on human health

Plastic pollution in our oceans can be harmful to human health. Microplastics—which can include chemicals like cadmium, mercury, and arsenic that are known carcinogens—have been observed not just in samples of ocean water but also in the food that we eat, particularly seafood. Microplastics have even turned up in our tap water. 

Economic impacts 

There are a variety of possible economic impacts of plastic ocean pollution. Countries and coastal communities that rely on the financial support of tourism feel the effects of plastic waste in the ocean most, as it can decrease the aesthetic value of a location, and disincentivize tourists from visiting, according to the International Union for Conservation of Nature. While communities around the world could feel the effects of this issue, one study looked at coastal towns in the United States in California, Ohio, Delaware, Maryland, and Alabama. The report found that nearly debris-free beaches meant an estimated increase of between 2% and 35% of recreational days across the different communities. ¹⁹ 

Climate change-related impacts 

Plastic debris in our oceans could actually exacerbate climate change, as scientists think that this waste could affect the ocean’s natural capacity to absorb and store carbon dioxide. One way this can happen is through microplastics ingested by plankton. Microscopic phytoplankton near the ocean’s surface typically absorb carbon dioxide from their surroundings. These tiny creatures bring that carbon dioxide from the surface down into the deep ocean in a process known as the “biological carbon pump.” Microplastics can damage these phytoplankton populations, which can in turn have a major impact on the ocean’s natural carbon cycle.

What can be done? Initiatives to reduce plastic pollution in the ocean

Every effort to reduce ocean plastic pollution boils down to one thing: Making and using less plastic to begin with. Efforts underway to combat the crisis include legislation—both domestic and international—community initiatives, and changes to our individual habits. 

Just 20 companies, including ExxonMobil, Sinopec, and Dow, are responsible for more than half of single-use “throwaway” plastic waste items globally.

International agreements and legislation

As individuals, we can work to reduce our contributions to plastic pollution, but on a larger scale political power can have an even bigger impact. As an example, the U.S. passed the 2021 Break Free From Plastic Pollution Act to reduce plastic production, increase the amount of plastic recycling, and protect communities most affected by plastic waste. Internationally, United Nations member states developed a global plastics treaty, signed by 175 member states. This treaty, which is still in development, will set global regulations to reduce plastic pollution. There have also been political efforts to reduce single-use plastic items across cities, states, countries, and larger regional blocs. 

Cleanup technologies

There are innovators who are working to create technologies to address the plastic debris already cluttering our oceans. For example, The Ocean Cleanup, a non-profit foundation, aims to remove 90% of existing floating ocean plastic pollution. They use computer models to predict where plastic hotspots are in the ocean; they then deploy a large floating barrier towed by two slow-moving vessels to corral and collect floating plastic. It is important to note, however, that this particular effort by The Ocean Cleanup has been heavily scrutinized over allegations of staging and the unintended consequences of such cleanup projects. 

Waste prevention and recycling initiatives

There are initiatives around the world to reduce the amount of plastic we’re creating and support recycling. A few examples include the plastic bag ban that started in 2002 in Bangladesh and came to New York City in 2020. The trend continues to spread to other U.S. cities and countries around the world. Microbeads, tiny bits of plastic in cosmetics that often end up as microplastic pollution, have also been banned across the world, starting in the Netherlands in 2014. Additionally, in 2018 the European Union announced a major strategy to create a “circular plastics economy,” by enforcing correct recycling and reducing plastic use. 

What can you do to reduce plastic pollution?

The plastic pollution crisis is such a big problem that it can seem impossible to fix, but every individual can make an impact on reducing plastic pollution. 

Reduce consumption and use alternatives 

One major way that you as an individual can contribute is by reducing plastic consumption overall. Plastic can sneak into so many of the products we use every day, but if you keep an eye out on packaging, products, and other plastic bits that you can cut out of your life, then you can actively reduce the plastic that will one day end up in a landfill or ocean. 

Proper waste management and recycling practices

Additionally, while we all might know to “reduce, reuse, and recycle,” proper recycling can be a bit tricky. You should always check what types of plastic are accepted at your local recycling plants and what plastic is collected by your local pickup, keep track of what types of plastics you’re using, and make sure that you are recycling the right types of plastic in the right places.

Beach cleanups and awareness campaigns  

Beach cleanups take place all around the world, and anyone can participate. Just a few major examples include the Versova Beach Clean-up in Mumbai, India, Ocean Conservancy’s annual  International Coastal Clean-up, the UK’s Great British Beach Clean, and the Puri Beach Clean-up in Odisha, India. In 2018, over a million volunteers picked up about 23 million pounds of trash in just one day during the International Coastal Clean-up, which takes place at dozens of beaches worldwide. In fact, you don’t need to be part of an official beach cleanup to clear plastic and litter from your local beaches. Make it a habit of filling up a bag every time you go.

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1. From Pollution to Solution, United Nations Environment Programme, Oct. 2021. ↩︎
2. The rise in ocean plastics evidenced from a 60-year time series, Nature Communications, Apr. 2019. ↩︎
3. Global plastics outlook: Economic drivers, environmental impacts and policy options, Organisation for Economic Co-operation and Development, Feb. 2022. ↩︎
4. Rapid increase in Asian bottles in the South Atlantic Ocean indicates major debris inputs from ships, PNAS, Sept. 2019. ↩︎
5.  Ghost gear: the abandoned fishing nets haunting our oceans, Greenpeace Germany, Nov. 2019. ↩︎
6. Industrialised fishing nations largely contribute to floating plastic pollution in the North Pacific Subtropical Gyre, Scientific Reports, Sept. 2022. ↩︎
7. Plastic waste makers index 2023, Minderoo Foundation, Feb. 2023. ↩︎
8. More than 1000 rivers account for 80% of global riverine plastic emissions into the ocean, Science Advances, Apr. 2021. ↩︎
9. Marine plastic pollution, International Union for Conservation of Nature, Nov. 2021. ↩︎
10. More than 1000 rivers account for 80% of global riverine plastic emissions into the ocean, Science Advances, Apr. 2021. ↩︎
11. Rivers as plastic reservoirs, Frontiers in Water, Jan. 2022. ↩︎
12. Plastic in global rivers: are floods making it worse?, Environmental Research Letters, Jan. 2021. ↩︎
13. Microplastics in seafood and the implications for human health, Curr Environ Health Rep, Aug. 2018. ↩︎
14. Microplastic pollution in deep-sea sediments from the great Australian bight, Frontiers in Marine Science, Oct. 2020. ↩︎
15. Marine plastic debris emits a keystone infochemical for olfactory foraging seabirds, Science Advances, Nov. 2016. ↩︎
16. Marine plastic pollution, International Union for Conservation of Nature, Nov. 2021. ↩︎
17. Plastic pollution on the world’s coral reefs, Nature, Jul. 2023. ↩︎
18. Zooplankton grazing of microplastic can accelerate global loss of ocean oxygen, Nature Communications, Apr. 2021. ↩︎
19. Study on the economic impacts of marine debris on beaches, NOAA Marine Debris Program, Jul. 2019. ↩︎