What Is the Carbon Footprint of Transportation? Driving big cars and flying short distances are the worst.

Lloyd Alter https://www.treehugger.com/what-is-the-carbon-footprint-of-transportation-5081940 October 13, 2020

Big personal vehicles have the highest carbon footprint
Big personal vehicles have the highest carbon footprint. Lloyd Alter

The statistician and engineer W. Edwards Deming once said “In God we trust. All others must bring data.” Some of the best data come from the Our World in Data team at Oxford University. Their latest looks at what form of transport has the smallest carbon footprint.

Carbon footprint of travel per kilometer
 CC Our World In Data

Probably to no one’s surprise, driving a big car is the worst. The data are all from the UK, so we are probably talking Land Rover here. The next worst way to travel is a short domestic flight. “This is because take-off requires much more energy input than the ‘cruise’ phase of a flight. So, for very short flights, this extra fuel needed for take-off is large compared to the more efficient cruise phase of the journey.”

Long-haul flights in the economy section don’t look that bad in terms of carbon per kilometer, but of course, one is traveling a much longer distance.

The first important question this chart raises is, why do we have big cars and short flights? The large car has almost double the footprint of a small one, and we are not even talking about the embodied carbon from making the thing, we are simply talking about fuel consumption. And look at the difference between national rail and domestic flight; both are covering the same ground, but one has six times the footprint of the other.

Oxfam emitters categories of consumption

From the Oxfam Carbon Equity study, we also know who is driving the Land Rovers and taking those short flights; mostly the top 10%, the wealthy. They are incentivized to spend more money to consume more energy, and they do, because as economist Robert Ayers noted, “the economic system is essentially a system for extracting, processing and transforming energy as resources into energy embodied in products and services.” There is more money in it for everyone.

What About Bikes?

Bikes in Copenhagen
Bikes in Copenhagen.  Lloyd Alter

Also interesting is that bikes and e-bikes are not included in the chart or in the options. (You can click on +add travel mode on the actual chart and pick your own mode of transport, but bikes aren’t there.) But they do mention them in the copy:

“Over short to medium distances, walking or cycling are nearly always the lowest carbon way to travel. While not in the chart, the carbon footprint of cycling one kilometer is usually in the range of 16 to 50 grams CO2eq per km depending on how efficiently you cycle and what you eat.”

The top number there is higher than rail or a small electric vehicle, which seems odd. In the footnotes, they explain:

“Finding a figure for the carbon footprint of cycling seems like it should be straightforward, but it can vary quite a lot. It depends on a number of factors: what size you are (bigger people tend to burn more energy cycling); how fit you are (fitter people are more efficient); the type of bike you’re pedalling; and what you eat (if you eat a primarily plant-based diet, the emissions are likely to be lower than if you get most of your calories from cheeseburgers and milk). People often also raise the question of whether you actually eat more if you cycle to work rather than driving i.e. whether those calories are actually ‘additional’ to your normal diet.”

The Our World In Data team relies on numbers from Mike Berners-Lee’s book “How Bad are the Bananas,” (which I rely on too) where he estimates the extra calories burned by doing exercise and estimates the carbon footprint of different diets, so a cyclist powered by bananas has a far lower footprint than one powered by cheeseburgers. It is a controversial argument that may well be twisted by the anti-bike types the next time they want to fight a bike lane, and is kind of ridiculous, everybody eats. Not only that, but a heavy driver burns more gas than a light driver, yet that is ignored. Bikes should be on that list, along with e-bikes, which come in at about 17 grams per kilometer.

However, they do conclude with recommendations that include:

  • Walk, cycle or run when possible – this comes with many other benefits such as lower local air pollution and better health.

Another recommendation might be to vote for politicians who would put a big honking carbon tax on fuel, to discourage people from driving large cars or taking short domestic flights. Looking at that graph, it’s staring us right in the face.