Easy Answer: Neither. Bring your own. But if you forget, you may want to choose the type of bag you’re most likely to reuse.San Francisco is considering expanding its plastic bag ban to include almost all retailers. The state of California is advancing a law that would ban plastic bags and make customers pay for paper sacks. China banned plastic bags last year. Which got me wondering—why all the hate for plastic? Are plastic sacks that much worse than paper?
Nope. Turns out both are pretty bad for the environment.
The production of both plastic and paper bags has environmental consequences; there are a number of studies out there devoted to the question of which one causes the most environmental damage, and no definitive answer (which is why reusable bags are still the best option – but I agree that it’s important to have a strategy for when you just don’t have one). For both plastic and paper bags, though, incorporating recycled content helps to reduce environmental impacts associated with manufacture. Many paper shopping bags have recycled content, but not very many plastic bags do. And most plastic bags are derived from fossil fuels, which are a non-renewable resource, while paper is made from renewable resources. On the other hand, plastic is lighter in weight than paper, meaning less fossil fuels are needed to transport a larger amount of plastic bags. Plastic also tends to be stronger and more waterproof than paper, which can mean greater efficiency in packaging (e.g., you might not need as many plastic bags as paper bags if you’re packing heavy or moist goods). In San Francisco, like many other communities in the U.S., it’s a lot easier for the typical consumer to recycle paper bags, since you can often do that in your home curbside paper recycling, but many grocery stores and other locations also collect plastic bags for recycling. However, plastic bags are trickier to recycle, and consumers don’t always to remember to bring bags back to the store for recycling. So there are a number of issues which can affect which bag has the greater environmental impact, including how you use it, how you make it, and which environmental factors you’re considering as most significant.
It probably doesn’t make sense for most communities to outright remove all single-use bag options without some kind of transition period, just because people are used to having free single-use bags offered to them, and it will take a while to transition to a society where we all remember to bring our reusable bags every time we visit a store. If some single-use bags are to continue to be available, though, we should figure out how to reduce their environmental footprint as much as possible.