You might want to be sitting down for this one. If the climate change situation has you in an anxiety spiral, no one would blame you for making small and big changes to reduce your carbon footprint. So that may mean flying less, reducing meat consumption, and taking your own reusable cotton tote bag to the grocery store.
And yet – not all switches are as beneficial as they seem. A recent study looked at the environmental impact of plastic shopping bags as compared to various types of reusable bags, and let’s just say the results weren’t exactly what you might have guessed.
The report, commissioned by the ministry of environment and food in Denmark, assessed the life cycle of the humble plastic shopping bag, and concluded that, all things considered, the bag may actually have the least environmental impact of all the options studied.
Of course, the most obvious thing to consider with plastic bags is that they do not biodegrade (at least, not within our lifetimes), and therefore create plastic waste in oceans, harm marine life, and add plastic to our food supplies. Which is nothing to dismiss out of hand. But that’s not the only factor to consider, climate change-wise. There’s also the effect of manufacture, air pollution, toxicity, ozone depletion, and water use. So taking all of those factors into consideration, your classic grocery store plastic bag may end up being the least harmful. And when weighing it all up, the cotton tote doesn’t exactly stack up with sparkling green credentials.
Let’s break it down: the study supposed that classic plastic shopping bags (technically named low-density polyethylene bags, LDPEs), were reused once (say, to line a trash can), and then incinerated. It then looked at how many times different types of bags – weighing manufacture, water use, etc – would need to be reused to have the same environmental impact. And the results might shock you. Quartz simplified the numbers, which revealed that conventional cotton bags need to be reused 7,000 times to be as environmentally friendly as a plastic bag that’s reused just once.
So, besides litter, plastic bags may be the least awful of several very imperfect options. Paper bags, for example, may be recyclable, but producing them requires more water and energy than plastic bags, and contributes to deforestation.
In fact, of all the options, organic cotton came out with the dubious honour of being the very worst option, requiring 20,000 reuses before being on par with a plastic bag. This is due to the resource-intensive production process, which yields 30 per cent less cotton than conventional cotton (and yes, this is after adjusting for other differences like requiring less fertilizer and pesticides). There’s also the lack of textile recycling infrastructure, which means it’s difficult to recycle.
This is all in the face of increasing bans on plastic bags, and other single-use items like plastic straws. So where does this leave us? One thing’s clear, and that’s when it comes to cultivating sustainable habits, it’s worth doing your research. Some switches are red herrings, and you may inadvertently be contributing to the very problem you’re trying to solve. There are no magic solutions, but armed with knowledge, bag by (plastic) bag, we can all begin to make small, helpful changes.