However, litter is a growing challenge to the marine environment. Whether it is plastic bags and bottles, discarded fishing nets or other industrial equipment – even printers dumped overboard from ships are not unknown on the ocean floor – it all adds up to a litter problem of such proportions that the United Nations has deemed marine litter one of the most important emerging environmental issues of our time.

Despite the scale of the problem, marine litter is still a relatively little-understood phenomenon. This was where the CleanSea team came in. Using a wide-ranging interdisciplinary approach, including expertise in areas such as ecotoxicology, oceanographic modelling, satellite imaging and materials biodegradation, as well as economic and policy analysis, its remit was to take the understanding of the causes and impact of marine litter to a new level, with the ultimate aim of providing policymakers with a ‘Roadmap for a Litter-Free Sea’.

For CleanSea’s Project Coordinator, Dr Heather Leslie, of the Institute for Environmental Studies at VU University in Amsterdam, The Netherlands, it is important to focus on society’s ‘blind spots’ regarding marine litter. “There are a lot of them,” she explains. “One can get locked into patterns of thinking, but if you want to make transformative discoveries you have to change this thinking. Being interdisciplinary is key. In our project we have everything from fishermen to hi-tech people to NGOs – people who would normally have nothing to do with each other on a daily basis,” she adds.

By assembling a team of such diverse backgrounds, the intention was to open up new perspectives and challenge existing patterns of thinking. “I encourage our researchers to go out to the very edge of what they know and take a good look around,” says Dr Leslie.

Among the aspects of marine litter that need to be better understood is the proportion of litter that is dumped at sea compared with the proportion that reaches the sea from land – for example from populated coastal areas or via rivers. Another is the role of ‘microplastics’. These are tiny plastic particles less than 5 millimetres in size including down to the truly microscopic, invisible to the naked eye. Extremely resistant to biodegradation they can result from the break up of larger plastic items, but plastic particles are also manufactured and used in a range of products and industrial processes and can be carried into the sea in wastewater flows.

As these issues indicate, the marine litter problem is a highly complex one with no single solution. For Dr Leslie, this reinforces the need for the project’s pioneering, multidisciplinary approach. So far, counter-measures have focused mainly on clean-up efforts – in other words addressing the symptoms, not the more complex causes. “What is unclear,” she says, “is the link to more systemic changes like cleaner production or better waste infrastructure.”  

According to Dr Leslie, economics is at the heart of the matter. “Marine litter is a symptom of a linear economy. We have it because we are not careful enough with our materials and we allow them to, one way or another, leak out of the technological cycle to nature, where they cause more ecological problems at product ‘end-of-life’. We spend billions of euros every year convincing people to buy disposable items and items with planned obsolescence. Of course, people do not value disposables or broken, unrepairable items and these are things that risk being dumped overboard, either literally or figuratively.”

“It is here that policymakers have a crucial role to play,” explains Dr Leslie. The aim of the policy ‘roadmap’ that CleanSea project team will develop is to help policymakers chart a course towards a ‘circular’ economy, in which resources are re-used. It may be a massive task, but for Dr Leslie there is no alternative. “There is so much litter out there. And business as usual is no longer a viable option,” she concludes.