Opinion – Leandro Narloch: Stop thinking that paper bags are more sustainable than plastic bags

One of the mysteries that most intrigues me in the behavior of environmentalists is the obsession of many of them with bags and paper straws.

Studies and more studies show that paper loses to plastic in almost all environmental criteria – among them, carbon emissions. Even so, the typical environmentalist considers it a “civilizing advance”, as Mayor Bruno Covas said, to exchange one for the other.

Plastic, as we know, causes a serious problem in places with poor public management of waste. But a good environmental impact analysis needs to consider not just the grave, but all stages of a product’s life. From raw material production, the emissions involved in manufacturing and transport, to use and disposal.

At least six times heavier than plastic bags and with greater volume, paper bags require six times more trucks (and fuel) to transport. Paper manufacturing occupies space that could be used for native forests or food production, unlike plastic, which is made from a by-product of refining gasoline.

A life cycle analysis carried out in the UK found that a paper bag uses more energy, four times more water, causes 90% more acidification of the atmosphere, 14 times more eutrophication (the accumulation of nitrogen and phosphorus in water) and almost four times more greenhouse gas emissions than a plastic bag.

Yes: in times of global warming, there are environmentalists advocating replacing plastic bags with four times more polluting alternatives.

Last week, McKinsey published yet another study on the climate impact of plastic. It measured “cradle-to-grave” emissions from plastic used in plumbing, in the manufacture of cars, bags, T-shirts and animal feed packaging, soft drinks, milk and water glasses. And compared it with emissions from alternative materials — paper, steel, aluminum, wood, cotton, wool, fiberglass, among others.

Of 14 applications, plastic did better in 13. “The production of paper bags causes three times more emissions than plastic bags due to greater use of raw materials and transport emissions”, says the study.

“The difference in impact increases to five times when you consider disposal and impact on use (such as ‘double bagging’).”

Does this data apply to Brazil? Probably yes, but I can’t be sure. There are no reliable lifecycle analytics around here. In general, each industry — paper and plastic — pulls the sardines to their side, giving a good stretch to the numbers that favor them. NGOs sponsored by these sectors go along the same lines.

Brazil has a modern paper industry that is concerned with environmental issues, but it is hard to believe that it is efficient enough to offset the smaller impacts of plastic.

The fact is, deputies and councilors across the country are banning bags based on anecdotal evidence of WhatsApp turtle photos, without seeking serious environmental impact studies.

Would it be the case to change the plastic or paper bag for the organic cotton ones? Depends on how often you use it.

According to Our World in Data, the organic cotton bag that everyone thinks is eco-friendly is only more sustainable than the plastic one if it is reused 2,375 times. Traditional cotton does a little better: it needs to be reused “only” 840 times.

The plastic bag is the closest thing to a perfect product: it’s cheap, light, waterproof, durable and capable of supporting thousands of times its own weight. This is precisely the problem. So good and cheap, we use it a lot — Brazil consumes more than 13 billion bags a year. Millions of them clog drains or end up in forests, rivers and the sea.

The most accurate solution here seems to be charging a minimum price. In several countries, charging a minimum price for grocery bags reduced their use by 80%. It may not be enough, but it is better than replacing them with much more polluting alternatives.