The complicated truth about plastic bags

Early this year, our town passed an ordinance banning single-use plastic bags. The bags are being phased out in stages: In Phase 1, which started this May, stores will have to charge shoppers 10 cents for each plastic bag they use (though they have the option of providing recyclable paper bags at no charge). In Phase 2, starting in November, stores will no longer be allowed to provide single-use plastic bags at all, but they may continue to offer paper bags for 10 cents each. These rules apply only to the bags used at the register; plastic bags used for wrapping up meat, fish, produce, and baked goods are still allowed, as are the plastic bags your newspaper comes in and the one the dry cleaner sticks over your clothes.

If all this sounds excessively complicated, there's a reason for it. The town went to a lot of trouble when crafting the law to make sure it wouldn't end up doing more harm to the environment than good.

You see, it turns out that the whole issue of plastic bag use is a lot more complex than it looks. As I noted back in my last Thrift Week entry, most of the alternatives to plastic bags cause environmental problems that can be even worse. A single-use paper bag, according to a 2011 analysis by the UK EPA, has a life-cycle carbon footprint four times as big as a plastic bag's. In other words, you'd have to reuse a paper bag three times to make it as green as a plastic bag used just once. And that darling of environmentalists, the cotton tote bag, would have to be reused 131 times.

In a Danish study from 2018, which looked at factors other than climate change—water use, ozone depletion, toxicity, and so on—these alternatives fared even worse. Assuming that a plastic bag gets reused once as a trash can liner before it's finally discarded, the authors concluded that a paper bag would need to be reused 43 times to be equally green, and a bag made of conventionally grown cotton would need to be reused 7,100 times. And in case you're thinking organic cotton would do better, the Danish scientists found just the opposite; an organic cotton bag would need to be reused 20,000 times—I repeat, TWENTY THOUSAND TIMES—to be as green as the much-maligned LDPE plastic bag.

And plastic bag bans can have additional, unintended consequences as well. NPR's Planet Money did a story on this in April, based largely on the work of Rebecca Taylor, an economist at the University of Sydney in Australia. She did a study comparing towns in California that had plastic bag bans to similar towns that didn't, and she found that in the towns with bag bans, people were buying more than twice as many small plastic bags, because they no longer had plastic shopping bags to line their trash cans or pick up their dogs' poop. And since these commercially available bags are thicker than the ones used at the supermarket checkout, this undid about 30% of the reduction in plastic use caused by the ban.

So does that mean banning plastic bags is just a straight-up bad idea? Well, not necessarily. Although plastic bags are in fact less harmful to the environment as a whole than most other types, they can do a lot of concentrated harm within a city. When people don't dispose of them properly—and sometimes even when they do, because an empty bag can easily get blown right out of a trash can—they wash into waterways where they harm wildlife, or clog storm drains and cause flooding. And since the easiest way to reduce plastic bag litter is to reduce plastic bag use, a ban can make sense.

The trick, then is to design a ban in such a way that it reduces the use of plastic bags, but doesn't encourage the use of alternatives that are even worse. Our legislators in Highland Park were apparently aware of this, which is why they went to so much trouble to make sure our ban wouldn't simply replace plastic bags with paper ones. They also somewhat addressed the dog poop/trash can liner issue by continuing to allow plastic produce bags and newspaper bags. These bags are probably less likely to become litter than plastic shopping bags, because people usually don't unpack them until they get home, where they can throw them straight in the trash—or save them to reuse when walking the dog.

All this was in my mind when I read on Nextdoor Woodbridge, a bulletin-board group for my neighborhood, about a proposed plastic bag ban in East Brunswick. I immediately chimed in to talk about the importance of making sure the ban doesn't simply trade plastic bags for paper ones, and to point out that according to Taylor's research, charging a fee for single-use bags does just as good a job of reducing their use as banning them, with fewer negative side effects.

Unfortunately, this suggestion didn't go over very well. Most of the people who commented seemed to be approaching the issue from the knee-jerk "Plastic is bad!" perspective, and they didn't want to hear any excuses for anything short of an outright ban. One person wanted to know why Highland Park was "selling" the bags for 10 cents a pop instead of eliminating them entirely:

Why are they made available at all ? Why ?? If the real concern is cleaning up the environment !! ???? Doesn't make common sense to me .

Another argued that there was no good reason to use plastic bags for bin liners or dog poop:

There are dog poop pick up products that decompose in the land fills. If you can afford having a dog or cat you can afford to buy or repurpose something else for this job. How about using paper bags for your small, bedroom, bathroom, office small trash cans. Maybe also try to compost or compost more and use larger paper bags for kitchen garbage cans as well. So you have to rinse it out ever once in a while.

These comments were kind of discouraging to me, because they directly contradict the best available science on plastic and the environment. "If the real concern is cleaning up the environment," then it makes perfect "common sense" to care about what people are replacing their plastic bags with, and whether it's more destructive to the environment than plastic. And it definitely does not make sense to encourage people to buy paper bags, with their much larger ecological footprint, as a "green" alternative to plastic.

But it seems that once people have it in their heads that plastic is Public Enemy Number One, nothing you can say will convince them otherwise. They already know what they believe in, so don't confuse them with your facts. I've encountered this same problem on the Plastic Free July site, where they recommend reusable bags "made from natural fibres such as such ethically-produced cotton" (which are much more destructive to the environment than single-use plastic) as "a fantastic alternative to single-use plastic bags," and suggest replacing your plastic trash can liners with "a few sheets of newspaper" (which has a higher carbon footprint than plastic") or "certified compostable bin liner bags" (which won't actually turn into compost in a landfill, but will break down faster than plastic, thereby producing more planet-warming methane).

So I guess the real point of this post is simply a plea to all my fellow environmentalists: Let's try to use our heads, as well as our hearts. I know the video of the turtle with the straw up its nose is incredibly upsetting. It makes you want to do whatever you can to stop things like this from happening. And on the face of it, banning these single-use plastics seems like an easy fix. But if we really want to help the ocean and the creatures that live in it, we need to do more than just grasp at the obvious solution. We need to actually consider all the impacts of our choices—such as whether the carbon emissions caused by paper bag production are more harmful than a bunch of plastic bags sitting unchanged in a sanitary landfill. If we ignore inconvenient facts and just rush toward the option we've already decided on, we're no better than the folks who deny climate change exists because they don't want to have to give up their steak and their SUVs.