Apr 18 2019

Should We Ban Plastic Bags

Probably – but it’s complicated.

That is often the unfortunate answer when we ask big questions about how best to manage the world. We want to feel good about ourselves for being good citizens, or at least champion clear policies that are objectively better and effective at achieving our goals. Reality rarely accommodates these desires.

Part of the problem is that there are over 7 billion people on the planet and growing, and our industrial civilization uses a lot of resources. So anything that millions or billions of people do is likely to have an impact. Because of this there may simply be no perfect option.

But further, the available options tend to have trade-offs. Therefore if you ask, which option is better, the answer often is – it depends. It depends on how you ask and how you answer the question. Defining the problem is often easier – the solution, not so much.

The problem here is clear – single use plastic products do not biodegrade. They survive in the environment for about 400 years. They will break down into microplastics, but these stay in the environment and can still cause problems. A recent study found microplastics in remote regions of the Pyrenees. They are basically everywhere. Plastics clog our oceans and increasingly animals are turning up dead bloated with plastic waste.

Those concerned about preserving the Earth’s environment as much as possible (which should be everyone) at various times turn their attention from one plastic product to another – bottles, straws, and now plastic bags are in the crosshairs. The UN estimates that the world produces between 1 and 5 trillion single-use thin plastic bags each year. Also, because these bags are light they can blow easily in the wind, which means they end up tangled in trees and elsewhere, causing more problems.

I think it is reasonable to conclude, and I have never heard a cogent counterargument, that the way we are doing things now is not sustainable. What will 400 years worth of plastic in the environment look like? What will be humanity’s steady-state of plastic garbage? We might be tempted to punt this one to the future, and hope their technology will fix it, but we may consider that we are the future our predecessors already punted to.

In any case – it is worth considering what policies and practices might best mitigate this situation. This is where we get into controversy, as their is no clean answer.

First, we cannot simply ban one option without asking a few questions. Primarily, what are the other options. What will replace the thing we are banning, and how good of an options is that? Further, we need to ask if there are any unintended consequences. What effect will the ban or change in policy actually have on human behavior. We also might want to know about cost, and therefore opportunity cost. Is this the best use of our time, money, effort?

With regard to single-use plastic bags vs other options, there are two big concerns: carbon cost, and waste. These two factors may not yield the same priority.

Regarding carbon cost (really energy efficiency) single use plastic bags are actually a good option. Paper bags cost three times the carbon. Cotton-based reusable bags would have to be reused hundreds or even thousands of times before they offset plastic bags. The best option is perhaps thick plastic reusable bags, but still they have to be reused a hundred or more times before they are a net benefit in terms of carbon.

Because of global warming it is now an increasingly good idea to limit our carbon footprint. So when we talking about changing entire industries, we need to to do a carbon efficiency entire lifespan analysis. Single use plastic bags, because they are thin, are actually not a bad option here, but the best is for everyone to use reusable bags for as long as possible – at least hundreds of times each.

Waste disposal gives a different priority. Single use plastics are perhaps the worst option, because they generate the most garbage, they do not biodegrade, and they find their way into the oceans and other parts of the environment. Paper bags are better because they biodegrade. Reusable bags are better because there are much fewer of them winding up in the waste stream. So again, reusable bags are a solid option if you reuse them a lot.

But there is more to consider. Studies find that when plastic bags are banned, people buy more plastic garbage bags, which are thicker and therefore use more plastic. It turns out, people reuse their plastic bags for waste disposal. By some estimates, however, this only reduces the advantage of banning plastic bags in about half, but does not completely offset it.

There is also the issue of recycling. There are some advantages to recycling plastic, and buying items that are made from recycled rather than new plastic. They still, however, ultimately end up in the waste stream.

The overarching problem is that plastic is cheap and convenient. It gets the job done, and can easily be mass produced. But we shouldn’t necessarily always follow this path of least resistance, because that path may not lead to a place we like. This is where evidence-based policy comes into play.

We may, ultimately, need to sacrifice a little bit of convenience in order to have a system which is more sustainable. Actually, I find using reusable shopping bags very convenient. They hold more stuff, and are easier to carry. You just have to think a little bit ahead and make sure they are available when you are shopping, by keeping them in your car, for example.

It is, of course, very difficult to get people to change their behavior just by telling them it’s a good idea. Banning plastic bags is one idea, but also just charging people for the bags is another option. These measures may help, but it seems they are insufficient to really address the issue. I feel like we do not yet have a great solution, one that is both waste and carbon efficient, that is maximally sustainable, and is easily adopted without people feeling like they are being inconvenienced (which affect compliance). Industry needs to come up with some clever solutions. A plastic bag that would rapidly and safely biodegrade, for example, would be nice.

Perhaps that is the best outcome of a ban on things like plastic bags. It may spurn industry to come up with those clever solutions, because we are depriving them of the easy but not sustainable ones.

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