Thursday, August 26, 2021

20,000 Bags? Exaggerated

CUNY professor Angus Johnston took on the job of analyzing that recent study you may have heard about, which proclaimed that a cotton tote bag has to be reused 20,000 times to make up for its manufacturing, compared to a flimsy plastic grocery sack. I had already seen a minor debunking of the study from an environmental reporter, but Johnston goes into a lot more depth. 

What's wrong with the analysis?

First, the study specified organic cotton, an adjective most people probably missed when they read about the study. It's not too likely all the tote bags you have, even if they're cotton, are organic. Conventional cotton uses one-third the resources of organic. And if your bags are made from recycled plastic bottles or some other material... who knows, maybe none of this applies.

The biggest challenge to the study's 20,000x claim, though, is that it's not about general climate impact at all. The cotton totes are only 50x worse for that kind of impact, even by the study authors' own measurements. Where did the 20,000x number come from? It's the authors' estimate of how much electricity (generated by natural gas) it takes to irrigate organic cotton and the impact that has on the ozone layer. Not on greenhouse gases. It's as if someone cherry-picked the biggest number they could find in the results, in order to get headlines.

The study's authors also assumed that the average plastic sack gets two uses, one to carry home the original product and again to take out the trash. Let's just say that we all know that is not true. (How many plastic sacks have you seen blowing down the street, or stuck in a tree? How many have you thrown away, especially if they were ripped?) 

Or at least it's not any more true than the authors' other assumption, which is that it takes two cotton totes to carry as much as you can in a plastic sack.

By the time Johnston was done, he had figured the average conventional cotton tote as at most 25x, with ones made from other materials possibly substantially lower. So if a cotton bag gets reused every other week for a year... you've saved 25 plastic bags while decreasing the need for oil to make the plastic bags and either landfill or incineration to dispose of them, plus you can keep using the bag some more. 

That's not to say that every organization and their brother should be giving out cloth bags all the time. None of us is saving the planet "one bag at a time."

But I think that trend has peaked, thank goodness. Let's all use the ones we have, or if we need one, get it at a reuse store, since there are plenty in existence already. I donated some of the ones that have been foisted upon me along the way to my local food shelf, which loves to get them.

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