It’s quite obvious that – at least in the Western world – we have quite a big problem with plastic. Whether it’s wasting so much on packaging, or putting too much in our bodies – either through plastic surgery or BPA exposure – it’s everywhere. Apparently, “the amount of plastic produced in a year is roughly the same as the entire weight of humanity”, though perhaps that doesn’t take into account that a few of us have been on diets so far in 2018. Plastic is definitely a huge problem, and it’s no wonder there’s a lot of focus on it as it is typically derived from oil, making it both non-renewable in addition to being non-biodegradable. By bringing the argument specifically to bags, there’s a lot less focus on comparisons such as paper or cloth bags, and I think it comes partly from this image that biodegradability is the most important point from an environmental perspective. However, is this the case? Are plastic bags really the worst for the environment?
In as few words as possible: plastic comes from oil and paper comes from trees. Deciding which bags have the biggest environmental impact is actually quite challenging because there are different ways to affect the environment: a lot of energy can be used to create a biodegradable product, or alternatively a less energy intensive process can produce a non-biodegradable product. Here we have one producing more CO2, whereas the other is producing something which is intrusive to the environment and entering the food chain. The former is actually a description of creating paper bags, the latter plastic bags.
Throwing bags to the wind
So what happens when we throw these materials to the wind, instead of caution? As previously mentioned, plastic is typically not biodegradable, meaning empty coke bottles with faded labels can now be found free of charge worldwide. In addition to being an eyesore and blocking storm drains, plastics are in particular a problem for marine life with “fatalities as a result of ingestion, starvation, suffocation, infection, drowning, and entanglement”.
However, it’s not necessarily better when it comes to paper bags. They have been shown to release methane when they end up in landfills because the paper lies under other waste, meaning that the paper is decomposed anaerobically (without oxygen). This process creates methane as a product, which is a very potent greenhouse gas.
In addition to the energy intensive process, you may be surprised to find out that paper bags actually produce 70% more air pollutants, 50% more water pollutants and use 4 times as much water in comparison to plastic bags. More plastic bags are also able to fit into a smaller space, so you can transfer more bags per lorry, leading to lower transport emissions.
The only other alternative are those tote bags you see dotted around, usually in close proximity to a pair of converse and a denim jacket. You can probably guess that they are also in fact terrible for the environment. One study showed that a cotton bag would have to be used 131 times to have a “lower global warming potential” than a single use plastic bag. Something worth taking into account is that these statistics are all for the production of new bags.
So given that everything just seems to be absolutely awful to use, what’s the best option to take? My first suggestion would be to use your ‘Fjällräven Kanken’, thereby eliminating the need for extra bags in the first place, especially because having a few potatoes rolling around your bag isn’t going to be causing you any big problems. Otherwise, recycled cotton bags are probably the way to go, as they would need to be used less to compare to a single use plastic bag, while having the potential to last years. The main reason for this is that, as a society, we really do need to move away from single use items if we would like to significantly reduce our impact on the environment. Therefore any bag which you already own will suffice, and try to use it as much as you can. The information above does show that while each bag has it’s pros and cons, there is a distinct answer to the question of which single use bag to use while you’re out and about: none.
Jack McGovan is a recent graduate in chemistry with a specialisation in ‘Energy and Sustainable Chemistry’ from the University of Groningen, the Netherlands. Following a job as a student journalist covering the energy transition, he has moved to Berlin where he is following his passion for working towards creating a fairer and more sustainable world. Seeing a gap in the way in which the world of science was communicated, he founded Delta-S. By writing source based content, he hopes to communicate his findings to a wider audience.