People are increasingly aware of the growing problem of plastic in our oceans. I’ve lost count of the number of times I’ve been told, “You know, there’s a great big island of plastic in the middle of the Pacific”. More often than not, they quickly follow up by mentioning that thankfully there’s a project under way to solve the problem by cleaning up the plastic. While it’s good that more people understand that marine plastics are a cause for concern, it’s unfortunate if the only two things they “know” about it are not entirely true.
Talk of the Great Pacific Garbage Patch conjures up images of a huge floating island of plastic; it is nothing of the sort. Eunomia’s research on behalf of both the European Commission and concerned businesses has repeatedly found a disconnect between what the myth might lead us to expect to find floating on the ocean’s surface and what is actually there.
Plastics do tend to accumulate in certain areas, driven by ocean currents. The highest density zone is in the North East Pacific with other accumulations in the North Atlantic and Indian Ocean. However, even in the Pacific gyre, the plastic is fragmented and dispersed and most plastic particles are well under a centimetre in size. The highest concentration found through sampling in this area is ten particles per square metre.
Indeed, most marine plastic won’t be found on the ocean’s surface at all. Ocean surveys conducted by Eriksen et al have estimated that only 250,000 tonnes are currently floating in the oceans’ surface. Though this is a large number, it represents a fraction of a per cent of the plastic that is believed to be residing in the marine environment. The vast majority is either deep below the ocean surface or washed up on beaches.
Eunomia’s research shows that there is an average of just 18kg of plastic per square kilometre of ocean surface in the Pacific gyre, and an average, across the entire ocean surface, of less than 1kg per square kilometre. By contrast, there are 70kg per square kilometre on the ocean floor – and two tonnes per square kilometre on beaches.
These data highlight some of the limitations affecting the widely publicised Ocean Cleanup project. The remarkable Dutch entrepreneur behind the scheme, Boyan Slat, has been very successful in attracting interest and funding, to move his vision of collecting and recycling marine plastics from concept towards reality. His work is admirable in many ways, and having a technology to cheaply remove plastics from the ocean surface would be worthwhile; but even when the technology works as intended, it will be addressing, quite literally, a drop in the ocean.
There are still some pretty formidable problems for Ocean Cleanup to overcome. One is how to collect minute marine plastic particles without, at the same time, sucking up tonnes of small-scale sea life; but from an economic viewpoint, finding reliable markets for any plastic that is collected remains a challenge. The material is degraded, bio-fouled and difficult to identify — not ideal characteristics for recycling feedstock.
It’s not impossible to make use of it, as demonstrated by the handful of niche products, such as skateboards and clothing, already being made from marine plastics – mostly with the aim of increasing public awareness of the issue. But developing products that can be profitably mass produced from plastic taken directly from the oceans will be a further challenge that needs to be overcome if marine plastics are to be collected and recycled on a large scale.
Despite its obvious attractions, collecting and recycling plastics from the ocean isn’t enough. Slat, to his credit, freely acknowledges this; but there is a danger that those who present Ocean Cleanup as the solution to the marine plastics problem undermine efforts to introduce measures that would have greater impacts. Without such changes, Ocean Cleanup will be like using a thimble to empty a bath whilst the tap is still running.
According to a much-quoted estimate by Jambeck et al, each year up to 12.7 million tonnes of plastic flows into the ocean globally. Around 20% of marine plastic comes from at-sea sources, most of which is abandoned or lost fishing gear. The remaining 80% comes from land, much of it comprising single-use packaging items such as drinks bottles or food packaging – although there are also concerns about primary microplastics such as microbeads in cosmetic products.
Ocean Cleanup may, in due course, decide that their arrays, which they plan to site in some of the most remote places on earth, may be better scaled down to collect floating plastic further ‘upstream’, from estuaries or coastal areas – before it reaches the oceans. That said, it is worth noting that the rigorous testing and research process that the Ocean Cleanup up has engaged in to date is certainly furthering scientific understanding in this relatively new field.
Clearly, if we want to deal seriously with marine plastics, we need to turn off the tap. We need to start with the most significant types of plastic waste: single-use items such as bottles, drinking straws and cotton bud sticks. The last two of these examples may be a surprise, but by item count, they are some of the most commonly found items on the UK’s beaches, and they can hardly be considered essential for a fulfilling life.
Some plastic items, such as plastic cotton bud sticks, could be banned; the use of others can be radically reduced through the imposition of levies, as we’ve seen with plastic bags. But some, such as plastic bottles, are going to be with us in quantity for the foreseeable future. For these, the key is to make sure that their value is retained in closed loop systems by providing a a clear incentive to prevent them from escaping into the environment.
One way to do this is through using deposit refund schemes (DRS), where consumers pays a deposit on buying bottled beverages and receive their money back when the container is returned to stores or other designated return points. This has already reduced litter and boosted recycling in countries such as Sweden and Germany. It’s a double win for recyclers: more material is collected, and the quality is improved due to containers being collected in a clean stream. A DRS isn’t the whole solution, and there are, of course, many other important marine plastic streams to address. However, by ensuring plastic bottles are returned for recycling, a DRS can have a profound effect on the way that plastic waste that might otherwise find its way into the marine environment, is dealt with.
Marine litter is a potent symbol of the limitations of the linear economy; and while the image of the Pacific Garbage Patch as a giant floating island may be a myth, the reality is troubling enough to make marine plastics one of resource management’s most urgent challenges. As long as our shops overflow with single-use plastics, and as long as no one has an incentive to limit their flow into the oceans, then it seems that our seas will continue to be inundated with plastic that is practically impossible to recover. If we can turn the tide, however, then the very same materials may yet become a real poster child for the circular economy.
Eunomia will be hosting a conference in Brussels on 29th September to clear up misconceptions about the marine plastics problem and to present new measures that could be adopted to tackle this growing issue.