A diver removes plastic waste from the sea floor in Hatay, Turkey on December 2, 2022. (Photo: Sebnem Coskun/Anadolu Agency via Getty Images)
“Every minute, a garbage truck’s worth of plastic enters the ocean,” researchers said.
The amount of plastic waste littering the Earth’s ocean floors could be up to 100 times the quantity floating on the surface, according to a study published this week.
Researchers at the Commonwealth Scientific and Industrial Research Organization (CSIRO)—an Australian government agency—and the University of Toronto in Canada found that up to 11 million tons of plastic are polluting the planet’s ocean floors, including microplastics and larger objects like fishing nets, cups, and bags.
“We know that millions of tons of plastic waste enter our oceans every year but what we didn’t know is how much of this pollution ends up on our ocean floor,” CSIRO senior research scientist and study co-author Denise Hardesty said in a statement. “We discovered that the ocean floor has become a resting place, or reservoir, for most plastic pollution, with between 3 to 11 million tons of plastic estimated to be sinking to the ocean floor.”
"Every minute, a garbage truck's worth of plastic enters the ocean."
Study leader Alice Zhu, a doctoral candidate at the University of Toronto, said that “the ocean surface is a temporary resting place of plastic so it is expected that if we can stop plastic entering our oceans, the amount would be reduced.”
“However, our research found that plastic will continue to end up in the deep ocean,” Zhu stated. “These findings help to fill a longstanding knowledge gap on the behavior of plastic in the marine environment.”
“Understanding the driving forces behind the transport and accumulation of plastic in the deep ocean will help to inform source reduction and environmental remediation efforts, thereby reducing the risks that plastic pollution may pose to marine life,” she added.
The study is part of CSIRO’s Ending Plastic Waste program, whose goal is “an 80% reduction in plastic waste entering the Australian environment by 2030.”
Humans produce approximately 440 million tons of plastics annually, or roughly the combined weight of every person on the planet. Plastic pollution harms not only the environment and ecosystems, but also human health and economies.
Plastic use is expected to double by 2040. Negotiations on a global plastics treaty have made little progress amid lobbying by the fossil fuel and petrochemical industries.
So much ocean plastic originates from sources on land, but once floating in the sea it poses a risk to marine wildlife and habitats. Rich Carey/Shutterstock
Plastic has been found in every single part of the ocean, from the surface to the seafloor and from the tropics to the poles. Land-based sources of plastic account for the majority of this pollution, with plastic bags, bottles, wrappers, food containers and cutlery among the most common items found.
These items are often buoyant and float on the sea surface. As they travel long distances, they get pushed by the wind, waves and currents. This means they have the potential to cause harm far beyond the country from which they originated. For example, land-based plastic waste from Indonesia has been shown to travel over 4,000km to the Seychelles.
As it travels, plastic litter can cause harm to wildlife. Megafauna (large marine animals) can eat or become entangled in it. Consuming plastic litter can block or damage the gastrointestinal tract of animals, causing significant health impacts or death.
While ghost fishing gear (lost fishing nets that float freely) is the most common entanglement threat to marine megafauna, they can also become entangled in land-sourced plastics such as plastic bags, frisbees, potato nets, elastic bands and other circular plastics. This can cause severe trauma to the animal, and in some cases entanglement causes death.
If plastic is transported towards the shore, it can get caught or lodged in shallow environments where it can entangle or cover plant or animal habitats, causing damage. Plastic entanglement can cause breakage, and if it covers a habitat it will restrict access to food or light.
At Plymouth Marine Laboratory, our team of marine researchers have developed a risk assessment approach to understand where this plastic litter could cause the most harm in the North Atlantic, and which countries that plastic originated from. Our research highlighted five areas of high risk – the US Atlantic, the US Gulf of Mexico, the UK, French Atlantic and Portuguese Azores.
Reducing risk
In our new study, we assessed the risk of land-sourced plastic litter to marine megafauna. That includes seabirds, whales and dolphins, seals and sea lions, manatees and dugongs, sharks and rays, tuna and billfish. We also assessed the risk to shallow water habitats including coral reefs, mangroves, seagrass beds, saltmarsh and kelp seaweed beds.
Using a particle tracking model, we tracked the flow of buoyant plastic litter released from the rivers of 16 countries bordering the North Atlantic between 2000 and 2015 using the most recent data available. Billions of virtual particles were released at the mouths of the rivers each month, with surface currents and wind used to drive their movement. After 15 years of tracking, our model showed us where plastic was likely to accumulate.
We also assessed the vulnerability of each of the megafauna groups and shallow water habitats to this plastic. For marine megafauna, we developed vulnerability scores by quantifying the amount of scientific evidence of ingestion or entanglement in land-sourced plastic. For habitats, we developed vulnerability scores by quantifying the scientific evidence available for this plastic causing harm by entanglement or smothering.
Marine wildlife such as this green sea turtle can become entangled in ghost fishing gear that is left floating in the sea. Mohamed Abdulraheem/Shutterstock
To assess risk, we mapped the vulnerability and distribution of each megafauna group or habitat against the abundance of plastic. Each point within the map was given a risk score from zero to five. The greatest risk occurred in areas where high numbers of vulnerable megafauna or habitats overlapped with high concentrations of plastic.
Managing the plastic problem
We found that much of the modelled plastic litter causing risk in the UK originated from UK rivers. In other high-risk zones such as the Azores and the US Gulf of Mexico, plastic primarily originated from other regions. More than 99% of plastic litter in the Azores was estimated to come from the other countries, mainly Caribbean islands and the US.
The potential of this plastic to travel vast distances across the ocean makes management of this pollutant particularly difficult. More than 90% of plastic waste in the Dominican Republic and Haiti are estimated to be mismanaged. This waste has the potential to cause ecological harm across both sides of the Atlantic.
UN member nations have agreed to forge an international legally binding agreement to tackle plastic pollution, called the Global Plastics Treaty, with negotiations expected to be completed by the end of this year. This study highlights the importance of the treaty in ensuring international cooperation to reduce plastic consumption and waste, including the provision of financial support to help lower-income nations such as the Caribbean islands implement measures. Identification of high-risk zones will also help prioritise areas where interventions and monitoring should be targeted.
Even if all plastic intervention measures are implemented, it is likely that substantial amounts of plastic will still enter our oceans. The production, sale and distribution of many of single-use items are likely to be phased out under the Global Plastics Treaty, as nations move to restrict avoidable plastic products.
While global measures are hugely important in the fight against plastic, the choices of consumers also play a significant role. Reducing, re-using and recycling plastic are powerful ways to cut your plastic footprint. At both ends of the spectrum, the choices made at international and household level can be good news for marine wildlife.
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Environmental campaigners warn that Ratcliffe’s controversial ‘Project One’ will bring ‘US-scale plastic production to Europe.’
Jim Ratcliffe, Britain’s pro-Brexit billionaire, hit the headlines this week with news that the government is providing a €700m guarantee for him to build the biggest petrochemical plant in Europe in 30 years. The plant will turbocharge the production of plastic.
Left Foot Forward takes a look at who Ratcliffe is, and how his controversial ‘Project One’ that will bring ‘US-scale plastic production to Europe’ is recieving significant financial guarantees from the Tory government.
Ratcliffe’s story is one of capitalist meritocracy, of someone who grew up on a council estate in Failsworth, Manchester, and went on to become the wealthiest man in Britain. He studied chemical engineering at Birmingham University and gained an MBA from London Business School in 1980. Having worked as a chemical engineer, in May 1998 he founded Ineos. The multinational is one of the largest chemical producers in the world and plays a significant role in the oil and gas market. According to the 2023 Sunday Times Rich List, the company’s owner, Ratlcliffe, is worth £27.9bn.
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This week, it was announced that the government is providing a €700m guarantee for Ratcliffe to build a huge petrochemical plant in Europe. The site will import fracked shale gas from the US to provide the ethane which will produce 1450 kilotons of ethylene – the building block of plastic – a year.
The plant is being constructed by Ineos in the Belgian city of Antwerp. Environmental campaigners have described the petrochemical plant as a ‘carbon bomb,’ warning that it will turbocharge plastic production on a scale not seen before in Europe, at a time when countries are hoping to negotiate a binding global treaty to tackle plastic pollution. The ‘Project One’ plant has faced a long-running legal battle by environmental groups. In the summer of 2023, the building of Ratcliffe’s €3bn plant was halted after a landmark court victory by the NGOs. A new legal challenge argues that the true impact of the development on people, nature and the climate has not been considered.
“There is a huge problem of plastic pollution from nurdles already in Antwerp and the Netherlands. This plant will bring US-scale plastic production to Europe,” said Jeroen Dagevos, of the Plastic Soup Foundation, one of the NGOs challenging Project One.
GREENPEACE activists scaled Unilever’s London headquarters on the eve of its profit announcement today.
The activists unfurled a banner reading “Profit Warning — Plastic Polluted Money” in protest against the company’s destructive use of environmentally harmful packaging.
The protesters then set up a pollution warning zone around the entrance to the headquarters, warning passers-by about the company’s overwhelming plastic pollution problem.
A previous Greenpeace investigation revealed the consumer goods giant as the biggest seller of some of the worst polluting packaging, multilayered plastic sachets. According to the report, Unilever sells 1,700 sachets every second.
The sachets are typically used to package products such as soap, shampoo and laundry detergent, and are virtually impossible to recycle.
Greenpeace say they exacerbate devastating floods when they enter the environment as they jam local waste systems and waterways.
