Sustainable Living Challenge

Week 31: Understanding Carbon Footprints

The term “carbon footprint” has been thrown around  within and outside of the green movement for years now. I hope we can all agree that a small carbon footprint is better for the planet. However, what exactly is a carbon footprint and how do we calculate it? More importantly, how accurate is the carbon footprint? This week, we’re diving into understanding what all the hooplah is about!

What is a Carbon Footprint?

Even in researching this article, I had a lot of trouble locating an agreed upon academic definition for the term, “carbon footprint”. Pretty much every paper I found about carbon footprints has their own definition of what they are considering a carbon footprint to be. The term started becoming more popular some time around 2007 but even after eleven years, we haven’t really agreed on one definition. Oftentimes, “carbon footprint” is used colloquially to mean the direct impact a product or action has on the climate, based on the amount of carbon emissions associated with that product or action. For example the carbon footprint of driving a car would be related to the amount of gas used during a given drive.

However, a more accurate measurement of a carbon footprint takes into account the indirect and direct impact a product of action has on the climate. In the car example, the carbon footprint would be measured based on the amount of gas the car used as well as the emissions associated with collecting the materials to build the car, the actual manufacturing process, shipping the car to your local dealership, and the fossil fuels used to operate the offices associated with the car manufacturer and dealer. Suddenly, the footprint gets much larger. For all intents and purposes, I personally think Mike Berners-Lee’s definition in “How Bad Are Bananas” covers it pretty well:

The best estimate that we can get of the full climate change impact of something. That something could be anything – an activity, an item, a lifestyle, a company, a country, or even the world.

How to Calculate a Carbon Footprint

Calculating a carbon footprint can be really tricky. It is very hard to account for all of the processes that go into making something like our car example. If you really want to consider all of the direct and indirect impacts of a vehicle, you have to think about things like how often the tires and batteries are replaced and the carbon footprint of those items. Or take an action like biking. This may seem like a carbon-friendly action. However, exercising means you eat more, and if you are eating lots of meat, you could be increasing your carbon footprint. Right now, calculating the actual carbon footprint of something it extremely difficult and complicated. It’s really hard to cover everything that could possibly be associated with a product or even an action.

Is the Carbon Footprint Accurate?

As you are probably already gathering, carbon footprint calculations can be highly inaccurate. A study from Carnegie Mellon found calculations of carbon footprints to be highly uncertain. According to this study, the estimated carbon footprint of a product could have anywhere between 15%-50% estimated uncertainty. That’s huge range of possible error! So if we want to put a number on something, we’re going to have a hard time.

Why We Should Still Care

Carbon footprints are still useful measurements because they are great for comparisons. Even though we can’t accurately measure the entire carbon footprint of driving, we can compare the estimated impact of driving to that of flying or taking the train. This still gives us a way to parse out more eco-friendly actions and products. If something has a relatively low carbon footprint, that may be a better option than something with a relatively high carbon footprint. So while inaccurate, talking about carbon footprints can give us a foundation to work off of and also help us figure out which products are being greenwashed and which ones actually help the planet.

Tools You Can Use

Carbon footprint calculators should be taken with a grain of salt. However, they can be a useful tool for tracking your improvement when going eco-friendly. My recommendation is to pick one and play around with it to come up with ideas for how you can reduce your impact on the climate. While these online calculators may not be super accurate, they can definitely help motivate you to go green. A few I found are from the EPA, the Nature Conservancy, and the Carbon Fund.

Another great tool is the book I mentioned earlier, “How Bad Are Bananas” by Mike Berners-Lee. This book details the estimated carbon footprint of everything from paper towels, to plane rides, and yes, bananas. The author himself goes into detail about the inaccuracies of carbon footprint calculations, but he does a great job explaining how he came up with his numbers. I’m still reading through it myself, but I highly recommend it!

Thanks for reading everyone! Still have questions about the carbon footprint concept? Leave a comment below!