Last year a member of my local Zero Waste group on Facebook asked if she should do bulk bin shopping in the context of living 20 miles away from the nearest store to offer it. Commentators on the post agreed that it probably was not a good idea. The additional miles driven would likely have a larger carbon footprint than the amount of plastic saved.
I wondered if there is a way to express miles driven as a quantity of single-use plastic. Here is my best ballpark estimate:
1 mile driven = 5.3 standard size plastic water bottles
How did I come up with this estimate? Here is the math:
- Every gallon of gas used represents 24 pounds of carbon dioxide and GHG (greenhouse gas) emissions.
- On average US cars get 24-25 miles per gallon of gas. To make the math easy I’m using 24 mpg, meaning that on average 1 mile driven = 1 pound carbon dioxide and GHG pollution.
- An average 500 milliliter plastic water bottle has a carbon and GHG footprint of about 3 ounces (16 oz = 1 pound, so about 1/5 of a lb.) Therefore 5.3 water bottles = 1 pound of carbon emissions.
A three mile round trip is the equivalent of purchasing a 16-pack of water bottles. I call this concept ‘invisible plastic’ and use it as a guide when it comes to reducing my carbon footprint. For example I wouldn’t drive across town to buy one zero-waste item if a disposable version is available at the Bodega next door to me. That’s an easy decision though, and most people don’t need the concept of invisible plastic to know that to be true. I recommend that when in doubt, calculate your journey in water bottles per mile driven, estimate if your shopping journey would save more plastic than that, and then compare to other car-free options you may have. It’s not perfect, but it is a good framework with which to examine your carbon footprint habits.
I’ve been thinking about this lately now that we are living in a world in which the COVID-19 health crisis is curtainling bulk bin shopping options, increasing take-out, and prohibiting reusable cups at coffee shops in favor of single-use ones. Most environmentalists, while pragmatic during these trying times, are nonetheless disappointed in the change to their zero-waste routines.
However, one silver lining to social distancing and shutdowns is an unprecedented reduction in air pollution and greenhouse gas outputs. Carbon emissions from fossil fuels are estimated to fall by 2.5 billion tonnes in 2020 due to the prolonged lack of factory production, flying, driving, and so on. That is 5 trillion pounds of CO2, or the equivalent of 26.5 trillion water bottles. That’s a huge quantity of invisible plastic.
Plastics have adverse health consequences as well, so moderation where possible is still best, but the COVID19 health crisis is much more immediate and deadly. Storms and tornadoes are also hitting many parts of the country, and the new advice is to seek shelter even if it means you can’t practice social distancing. It illustrates the hierarchy of threats to human health and safety, where the most immediate threats take priority even if it has negative consequences for other health risks. Sadly there is no perfect answer or solution in these situations.
Don’t beat yourself up over our current need to prioritize public health over single-use plastic consumption. Given the immense overall carbon emission reductions, we are giving Mother Earth a much needed break from our human-made pollutants.
There have also been dramatic increases in home-baking, vegan and vegetarian food purchases, and gardening, all of which help reduce your single-use plastic and carbon footprint. Have you been baking bread? Planting lettuce? Eating more beans and Beyond Burgers? If so let us know! Share with us on social media.