Measuring Carbon Footprint: Flawed, but Essential

footprints

I recently read Mike Berners-Lee’s excellent book How Bad Are Bananas: The Carbon Footprint of Everythingwhich uses detailed research and painstaking calculations to give realistic ideas of the carbon* footprint of many of the things we do in daily life. What’s the difference between buying asparagus and frozen peas? How does train travel compare to car travel? What’s the impact of a traffic jam? Berners-Lee answers these questions and many others.

One catch is that neither Berners-Lee nor anyone else can give exact numbers for any of these things. For example, the carbon footprint of eating a banana differs a whole lot depending on whether you’re buying it practically off the boat in Miami or from a grocery store in Topeka, Kansas because of the transportation element. The impact of driving a car depends not only on the kind of car, but also on its age, how long you plan to keep it, how well it’s maintained, how often you drive it, and many other factors.

Some of these complications are minor and can be ignored, but others are major. For example, you’d think that between clothing made from natural fibers and clothing made from polyester or other petroleum-based products, the natural fiber clothing would always be greener–but what about laundry? It turns out that washing and drying clothing can be a much bigger factor than the manufacture of the clothing in the first place, and a pair of jeans requires much more energy from a dryer (if you use one) than a pair of synthetic fabric pants.

An even worse complicating factor is that different sources disagree hugely on what the footprint of a particular item or activity really is, and most of these sources greatly underestimate the footprint. For instance, you may have heard statements about the carbon footprint of different vehicles, but in many cases those statements only cover the fuel consumption of the vehicle, and even then don’t take into account the infrastructure and supply chain necessary to deliver the fuel, but rather just what’s coming out of the tailpipe. Berners-Lee makes a special effort to be complete in this regard, but even he readily admits he is likely to be missing some factors in at least some cases.

This doesn’t mean that we have to nail down every last gram of impact and get some kind of complicated analysis of every little thing we do. It also doesn’t mean that because the answers can’t be exact most of the time, we should give up on counting carbon. It just suggests that the most useful approach is to understand carbon footprint numbers as guidelines and to make the best decisions we can based on those guidelines.

For example, it’s next to impossible to quantify exactly what the footprint of manufacturing and transporting a solar array is, or to know the potential footprint of the electricity the array replaces (though it’s often safe to assume it’s from coal, for reasons explained in the book). At the same time, it’s easy to see from even rough calculations that regardless of where these numbers land exactly, installing an effective solar array makes for a huge reduction in carbon footprint.

Annoyingly (to me, anyway), Berners-Lee is not much of a booster of solar power for reasons essentially unrelated to its carbon impact, and I think his analysis on that point is off-target. This is one of my many minor peeves about the book, yet on the whole it’s extremely useful. I hope to cover more of both its good and bad points in future posts. In the mean time, if you’re at all interested in understanding your personal impact on the climate–and everybody else’s, for that matter–may I suggest you buy the book?

*Like Berners-Lee and many other people who discuss the subject, I use the term “carbon footprint” as shorthand for “carbon dioxide equivalent,” which is to say the impact of all greenhouse gases, all of which can be calculated as being equivalent to a certain amount of carbon dioxide (CO2) in the atmosphere. While there are a variety of greenhouse gases, CO2 is the most abundant, though it’s not as damaging gram for gram as most of the others. Anyway, it’s unnecessarily complicated in most situations to talk about “carbon dioxide footprint, nitrous oxide footprint, methane footprint, and refrigerant footprint” and then to have to do a bunch of extra math from there when we can just use conversion factors and talk about “carbon dioxide equivalent.”

Photo by liknes

You want me to stop doing WHAT?

Flying. I’d like it if you stopped using airplanes. I’m not saying you have to or that I’m going to make you or that you should: I’m just hoping you’ll think about it.

downed airplane

The number of things we could be doing every day to reduce our carbon footprint and fight climate change disaster is unmanageable, overwhelming. Reducing paper and plastic use, recycling, reusing, repurposing, gardening, public transit, local foods, avoiding processed foods, solar and wind power …  I don’t know if you have time to tackle it all at once, but there’s no way I can manage. I have to change at most a few things at a time–which is why it’s essential for me to to figure out the things I can do that will make the greatest impact and do those first.

Number one on my list? Not flying.

For millions upon millions of years, not flying for humans has been a no-brainer. Then the airplane comes along and suddenly we’re Jonathan freakin’ Seagull.

I totally get the wonder of flight. I don’t mean the feeling of it, which for humans generally means getting a little queasy, trying not to spill the little airplane meal, and looking out a small window at a weirdly disconnect landscape; I mean the possibilities. Years ago I flew to Japan, and while I visited, there wasn’t a day I didn’t look around me to see and feel that holy crap, I was in Japan, and my two shoestring trips to Europe after I got out of college felt even more life-changing to me. On the other hand, as wonderful as those trips were, did I really need to go to Japan or Belgium or Hungary? No, not really. It was fun and fascinating, but there are other fun and fascinating things to do in the world.

Travel to foreign countries used to be one of my favorite things. Now that I see the real cost of it–which is not counted in dollars but in disasters–the shine has worn off.

I understand there are a lot of people who travel for business. The first thing I would suggest is that this often isn’t strictly necessary, just convenient and even, from a cost standpoint, reasonable. The second thing I’d suggest is that if you’re in a business that really does require a lot of air travel, you could make a disproportionately huge, positive impact on climate change by finding a way to cut way back, or to stop it. The third thing I’d suggest is that if your job really requires air travel and you don’t have the means to change it, it may be worth considering another job if you want to fight climate change.

Easy for me to say, though. Except for vacations and writing-related events, I generally have no reason to fly. Yet it being easy for me to say this doesn’t take away any of its importance. I’m sure I’d be more convincing on the subject if I were a former world-traveling business prodigy who had stopped flying instead of some schmuck who started taking regional vacations, but I’m doing my best.

Just how bad is air travel? Of course it depends on the specifics, but two or three round trip transatlantic flights can do as much damage to the climate as everything else an average American might do during the course of a year put together. All of the heating fuel, the driving, the fertilizers and fuel to bring you food, the cow methane, the household waste, and everything else: it’s doubled by a few flights.

As far as alternatives are concerned, the best and easiest is often to stay put or go to some alternative destination close by. Trains, boats, and buses are good bets, each having a much smaller carbon footprint than airplanes. Even cars are a lot better than planes, with hybrid, plug-in electric, and highly fuel-efficient cars of course being the preferred way to go. A trip by car can come close to emitting the same amount of greenhouse gases as a flight of the same distance, depending on the circumstances, but airplane emissions occur high in the atmosphere, where they have several times the impact they would have on the ground.

No one is going to stop you from flying. Few people even care at this point, but I hope you’ll be one of them, if you aren’t already. If fighting climate change is important to you, there’s not a single thing I can recommend that can reduce your footprint so easily and so profoundly.

Photo by The_ Incredible_ Mr.E