Plastic waste floating in a canal in Amsterdam, The Netherlands

When it rains it pours: How can cities save the ocean from plastic pollution during heavy rainfall?

Plastic waste floating in a canal in Amsterdam, The Netherlands
Amsterdam: Plastic waste floating in a canal in Amsterdam, The Netherlands

Charles Axelsson, a PhD researcher at Italy’s Ca ‘Foscari University, studied his Master’s at Imperial College London, where he worked closely oceanographer and climate scientist Dr Erik Van Sebille. In this blog, he considers the impact of urban plastic pollution on marine environments, and how policy and local action can help coastal cities save the ocean from plastic.

We are a planet of urban, coastal dwellers. Half of our world’s 7.5 billion people live by the coast and three quarters of our large cities are coastal. With this comes pollution problems, and in particular, plastic pollution. Macroplastics – plastics larger than 5mm – are not always properly managed by waste management companies. As a result, plastic bottles, plastic bags, the plastic in cigarette filters, plastic cups and all manner of other macroplastics collect in the urban environment. As well as being unsightly, this plastic poses a real threat to the environment. When it rains, it is washed out to sea, where it can have a seriously damaging effect on the marine environment. And this problem is only going to get worse. Climate change is causing rainfall patterns to change. Some urban areas are experiencing high-intensity rainfall more frequently and, as recent Hurricane Harvey, Hurricane Irma and the monsoons in South Asia have shown, heavy rainfall can inundate cities very quickly. This increases the potential of large amounts of urban plastic being washed out to sea.

Does existing policy help prevent this?

There are already a plethora of policies designed to protect the urban environment, such as regulation around stormwater and rainfall management, laws on recycling and littering, and taxes on certain materials – to name just a few. However, there is no clear framework for managing urban rainfall, flooding and plastic. In fact, there is no clear consensus on how to manage this problem at all.

What can cities do?

In my latest paper, Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events, I outline four ways coastal cities can help save the ocean from plastic:

  1. Create an overarching plan, with policies to match

No problem stands alone – policies will always be more effective if they are part of the bigger picture. Work with neighbouring areas to develop a regional strategy. Where there are gaps in knowledge, invite specialists to join the discussion and use their expertise. Then create ambitious targets, and share the responsibility of meeting them. For example, for cities to increase recycling rates, the municipal government can increase recycling infrastructure, nonprofit and specialist groups can focus on education campaigns and the local council can focus on enforcing the recycling laws.

Perhaps the most important of all is to focus on citizen engagement and education. Policies will not be effective if citizens aren’t aware, don’t care or resist change. Policies are good on paper, but actions speak louder than words.

  1. Manage the water

Cities need to spend time and money to understand how rainfall-induced flooding effects their city. If they don’t know why, where and how the city floods, how can policies be effective in reducing this risk? Once there is a thorough understanding of how rainfall impacts the city, there are a number of options to reduce the risk of floodwater washing plastic out to sea:

  • Encourage green infrastructure, such as green roofs, pervious pavements, rainwater harvesting and parklands, to divert, slow and absorb the rainwater.
  • Do away with combined sewer overflows. Combined overflows connect stormwater to the sewage line. This means that, when there is a lot of rainwater, overflow stations release a mix of rainwater, sewage and subsequent toxins directly into the waterway, creating environmental hazards – something Thames Water was recently fined for.
  • Establish tax incentives to encourage individuals to invest in flood-proof, green infrastructure.
  1. Manage the plastic

Cities should intensify their efforts to combat littering. Increase the number of recycling bins in public spaces, and make sure that people use them by implementing stricter fines and enforcing them. If this is done consistently, citizens will soon change their behaviour – recycling plastic and protecting the environment will become the norm.

Cities should also seriously consider bans and taxes on plastic material. For example, many retailers across England have introduced a charge for plastic bags  – a measure that has caused a dramatic drop in the number of single-use plastic bags. Similarly, some cities – including all those in New York State – have introduced a plastic bottle deposit schemes, whereby all beverages have to be sold in returnable containers. Cities could even go one step further and impose an outright ban on certain plastic materials – as San Francisco did with single use retail bags.

  1. Clean up the environment

Make a concerted effort to clean up the waterways so that storms don’t wash existing plastic rubbish out to the ocean. Start by creating dedicated departments to manage the cleanup, or contract nonprofits to take control. Raise awareness about the issue by engaging with citizens and getting them involved, and provide tax credits for individuals who fund these projects. For example, private companies or individuals could pay to adopt sections of the beach where they fund cleanup and maintenance efforts – much like the ‘adopt-a-highway’ scheme in the United States. In return, they generate tax benefits for themselves, and are able to promote their commitment to the environment.

Far-reaching benefits

Plastic in the ocean may not seem like a pressing problem for cities, but it should be. Plastic is hugely damaging to local wildlife, and the toxins it release may well come back to us through the food web. It is imperative that we work towards solving this problem – and doing so will not only benefit the marine environment, but also improve aspects of urban life. It will limit the spread of disease and toxins caused by macroplastic pollution; help cities to build a community of engaged citizens; and create more green space to improve the urban environment. And – thanks to flood-proof infrastructure and rainfall management – help to limit damage caused by floods. With so much to gain from tackling plastic pollution, there really is no excuse for cities not to take it seriously.

Find out more about the Grantham Institute’s work on plastic pollution in the ocean.

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