Plastic debris in our marine environment has become an enormous environmental problem. The volume of debris has been rising steadily in recent years and has formed noticeable garbage patches in the Pacific Ocean, as is shown in the NOAA picture above. Marine debris consists of plastics litter, fishing gear, and other items. Microplastics are a particularly problematic because these types of plastics can be ingested by fish, seabirds, and other marine animals. Lost fishing gear can also entangle marine life. Research by Moy (2018), Jang (2018), Buhl-Mortensen (2017), Duhec (2015) and others point to a variety of plastics that contribute most of the debris. Moy's (2018) study in Hawaii points to fishing nets and line (22%), buoys and floats (11%), foam (3%), and all other plastics (47%), as main contributors. In the Nordic Seas, Buhl-Mortensen (2017) found that fishing gear was the dominant source of marine debris.

The problem of plastic waste is closely linked to the enormous increase in the global production of plastics (polymer resin and fiber). According to Geyer (2017), worldwide output exceeds 400 million metric tonnes per year (MMT/a). Only about one fifth of this is recycled, another fifth is incinerated, and three-fifths are discarded. The authors of the study also estimate that about 30% of all plastics ever produced remain in use today. Mass-produced plastics do not biodegrade well. Sunlight weakens and fragments the materials into millimeter and micrometer size and thus creates microplastics.

The solution to the problem consists of prevention and removal. Turning off the influx of new debris is paramount, while novel technologies need to be developed to remove the existing debris. Both prevention and removal are challenging because they are mostly the domain of national policies, while the environmental consequences are global and also mostly outside the boundaries of territorial waters. But where does all the marine debris come from?

A 2015 study by Jambeck and co-authors has tracked the origin of the plastic waste. East-Asian countries are accounting for most of the problem. The authors apply a range of conversion rates from mismanaged waste to marine debris and estimate the mass of plastic waste entering the oceans from each country in 2010. They also project these estimates to 2025. The table below shows the key numbers from their analysis: the plastic marine debris from each country each year (upper estimate). The authors find that about 100 million metric tons of plastic waste was generated in 2010; about a third of this is mismanaged, and about 1.7-4.6% of the total plastic waste generated in those countries ended up in the oceans.

The fact that Asian countries account for so much of the plastics problem raises the question: what are they doing about it? As was widely reported, China has stopped importing plastics waste. As Parker and Elliott (2018) report, in 2016 China imported about two-thirds of the world's plastic waste, much of it coming from the United States and Japan, but also a significant amount from Canada. It has been cheaper to ship plastic waste to China than to recycle it at home. Now that China has stopped accepting waste, it is being shipped to other Asian countries. However, these alternative locations have quickly reached capacity limits. That so much plastics waste is shipped abroad reveals an underlying problem about recycling at home. Plastic recycling has not been economically viable in most instances. High-value plastics are mingled with low-value plastics, and many types of plastics are contaminated with food waste and other materials. So what can we do about all of that? The answer is: prevention and removal. First, focus on prevention. This means reducing the amount of plastics waste, and reducing the amount of single-use plastics is an important part of this strategy.

Canada's federal government has proposed a single-use plastics ban by 2021, joining a growing global movement. Canada is still far away from a "circular economy" when it comes to plastics. Whether a ban is the most effective policy is debatable, however. A life-cycle analysis by the Danish Ministry of the Environment found that plastic carrier bags actually have a low overall environmental impact compared to alternatives (paper, textile, composite), and that this can be enhanced by frequent re-use and eventual use as a waste bin liner. The risk of an outright ban is the possibility of undesirable substitution effects, as many people still use bags to collect waste. Integrated waste management requires looking at all waste streams together, and it also requires making comparisons with alternative materials. If banning single-use plastics simply leads to an increase in other single-use materials, fixing one problem creates a new problem somewhere else. The broader problem is that there are too many single-use products, many of them made from plastics, but many made from other materials as well.

When it comes to substitution effect, policies can sometimes foster "bad substitution" towards products that cause other types of environmental problems, but they can also foster "good substitution" towards more environmentally-friendly products. One example of "bad substitution" involves single-use plastic products that are labeled as "oxo-degradable". This is actually not the same as bio-degradable. Oxo-degradable plastics contain an additive that speeds up fragmentation—this still results in microplastics that do not break down at the polymer level. These oxo-degradable plastics are not a solution to the problem. However, compostable plastics certified by international standards such as ISO 17088, or ASTM D6400 in the United States and EN 13432 in the European Union, will ensure bio-degradation within half a year. These materials need to be processed by municipal composting facilities that have sufficiently high temperatures (home composting won't suffice).

To reduce overall use of plastics, there needs to be a price on waste that truly reflects the negative externalities it causes. A fee on single-use plastics that captures the cost of disposal can help direct demand to more sustainable alternatives. Grocery stores used to give away shopping bags for free, which results in over-use because the "free" is actually a subsidy by the grocery stores. Many grocery stores have gone voluntarily to charging for bags, usually about 5 cents per bag. Several jurisdictions are moving in this direction as well. The City of Chicago imposes a US7¢ fee on plastic bags (2 cents go to retailers, and 5 go to the city). The state of Illinois, where Chicago is located, will impose a 10¢ charge for the rest of the state, with 3 cents going to the retailer, 4 cents to the Carryout Bag Fee Fund, and the remainder to fund recycling and waste management research. In the United Kingdom, introduction of a 5-pence fee resulted in a 85% drop of bags, The Guardian reported in 2016. The UK announced it would raise the charge to 10 pence.

From an economist's perspective, the bag fee is the way to go, rather than an outright ban. While it may appear that a ban is simpler and "costs nothing", this no-cost notion is not quite true. Plastic bags still provide a useful service, and this needs to be replaced with something else. California banned single-use plastics since 2017, and the LA times reported that The world didn't end, with very few complaints. Still, a ban is a drastic measure, and it may direct demand to unsuitable alternatives. The point of environmental policy is to bring the private cost and social cost of economic activities in alignment—and this means finding the correct price that corrects the environmental externality. A modest bag fee (10¢ is about the right order) will accomplish this mission. Moreover, a bag fee should also apply on single-use paper bags, appropriately differentiated. (After New York State decided to bring in a single-use plastics ban similar to California, New York City decided to impose a US5¢ fee for single-use paper bags). Similar recycling fees should be applied to other plastic products in order to encourage appropriate substitution. The way to guide policy making in this area is through life-cycle assessments that identify the full cost of use relative to alternatives.

While a plastics fee is the first-best environmental policy, are there reasons to embrace an outright ban as a second best option? In an election year, showcasing environmental policy is important, and a simple ban is probably more "visible" and easier to grasp for voters than a more complex and nuanced plastics fee policy. Canada's federal government is probably also concerned about its jurisdictional authority to bring in a fee, as it could set the stage for conflicts with the provinces that have primary jurisdiction over local environmental concerns. The outright ban in response to the global effects of marine debris is probably well within the scope of the federal mandate for oceans, as well as the federal criminal law powers that are the basis for the Canadian Environmental Protection Act (CEPA). Seen through this lens, the federal government's maneuvering room is somewhat limited, and the ban is probably the "safer choice" on constitutional grounds. This said, it remains a second-best approach. The alternative, in my view, would be to set a national plastic waste reduction target and cooperate with the provinces to choose their preferred approach to meet the target—including plastic waste fees. The federal ban would then only apply to provinces that opt to do nothing. Unfortunately, several provinces already have an antagonistic relationship with the federal government and are keener on conflict than on cooperation.

Beyond prevention there is removal. Actually scooping up marine debris is economically unfeasible at this point (although a Dutch non-profit is trying). To the extent that plastics waste enters the oceans through our water treatment facilities, we also need to look at novel water treatment options. For example, Perren, Wojtaskik and Cai (2018) look at electro-coagulation as a novel option. Talvitie et al. (2017) and others point to membrane bioreactors (MBRs) and crossflow membranes, well-established technologies for water treatment. All considered, membrane technology is probably the most reliable option in the near future, but it is costly.

All considered, the federal ban on single-use plastics is a defensible measure but not the first-best measure. A fee on single-use plastics would be better than an outright ban. The federal government should, therefore, give provinces the option to implement alternative policies that meet a federal reduction target (e.g., 85% by 2025), thus giving provinces the option to work with fees instead of bans. More is needed still. Marine debris from fisheries operations needs to be targeted, and wastewater treatment needs to be upgraded. Lastly, plastic waste that cannot be safely landfilled needs to be incinerated in waste-to-energy facilities. Reducing the use of single-use plastics will not alone solve the ballooning plastics waste problem. We need a more integrated and holistic nation-wide plastics waste management strategy that gets us closer to the notion of a circular economy. This includes more product stewardship by manufacturers who need to take greater responsibility for the use and disposal of the products they make.

Improving Canada's recycling system can also help. Other countries show how to do it effectively. When I visit Germany, I marvel at the vending machines in supermarkets that take back recyclable bottles and cans of all types, which are subject to a deposit return fee. As described in Has Germany hit the jackpot of recyling?, the system generates high recycling rates because single-use plastic bottles also come with a higher deposit (25 cents) than reusable bottles (8-15 cents).

Perhaps we should thank China for creating today's "plastics crisis" by refusing our waste. It forces us to consider new policies for waste reduction, innovation into more sustainable forms of packaging, and adopting more efficient recycling and waste management systems.