# If a person uses public transport, how much carbon is added to the footprint?

For example if I use a public transport which is burning fuel with or without my presence, how one could calculate carbon footprint?

Hope I am in the right place for asking this question.

• Just may be a Sustainability SE question, but I'd lean towards it fitting here really. No matter though, good you asked, and we'll work out where it goes and get it there :) – JeopardyTempest Apr 2 '18 at 10:12
• as this question is now it is broad,what type of transport is it,bus-train-boat and how far do you travel. – trond hansen Apr 2 '18 at 13:55
• @trondhansen I guess this question can be understood as broad but then again it also can be understood as general question for all transportation types. For example you can generalize it in a way: "How much people affect carbon footprint by using transports that use fossil and/or electric vehicles?" Therefore it can be understood as scientific or philosophical. – titus Apr 2 '18 at 22:36
• @titus : Repeating your question with my own words, you mean the following: Buses, trams etc. emit greenhouse gases and air pollutants independent whether you use them or not. Depending on whether one or ten people use a bus, the carbon footprint of the user considerably varies. However, the carbon footprint of the bus as a whole does not vary much.How do we take this into account when we calculate the carbon footprint of one person? – daniel.neumann Apr 3 '18 at 8:34

I'm no expert on such subjects, but did Google and immediately this Guardian article offering a dataset apparently attributed to Camden Council/travelfootprint.org/Clear Zone Partnership. There are a lot of different values, but (if I understand the columns labels correctly), a rough breakdown of the footprints would be ranges of:

Bus: 20-90 g CO$_2$/km
Train, Diesel/Diesel-Electric: 30-150 g CO$_2$/km
Train, Electric [Long-Distance or Subway]: 10-70 g CO$_2$/km
Flight: 190-460 g CO$_2$/km

Walking: 5-25 g CO$_2$/km
Biking: 7-18 g CO$_2$/km

Basic car, Diesel: 40-180 g CO$_2$/km
Basic car, Gasoline: 40-200 g CO$_2$/km
Basic car, Liquefied Petroleum: 30-180 g CO$_2$/km
Basic car, Natural Gas: 30-150 g CO$_2$/km
Basic car, Gasoline Hybrid: 30-150 g CO$_2$/km
Basic car, Electric: 7-110 g CO$_2$/km
Motorcycle: 20-190 g CO$_2$/km
Scooter, Electric: 4-30 g CO$_2$/km

[See the report for other automobiles, including family cars, SUV, and minis]

(The best end of the range is the more efficient models run at peak capacity in best conditions [rural roads/medium distance short-haul flights]
The worst end of the range is less-efficient models at quite low capacity in less-efficient conditions [urban roads/very short or long-haul flights]
[Rail appears fairly similar in all usage circumstances, thus only depending on model/network setup, at least in this UK data])

This data attempts to take into account secondary sources (such as power plants for electric vehicles or needs of the agriculture which is used for the energy to walk/bike). As you can see there's a wide range depending on how most transport is used. You're best suited diving further into the table to find the most applicable use case for you.

My list only shows CO$_2$... the database also includes NO$_2$ and some others pollutants (if you can break down the abbreviations!) which can be very important too.

And this is UK-specific. So the equipment models used, network efficiency, and even climatological conditions will vary for other locations.

The date on the article also suggests its almost a decade old. So we have likely seen some additional improvements in some formats (though it seems unlikely that they are giant leaps in most cases).

Hopefully someone will come along with more recent and wide-ranging data, but this seems like a good start at some rough estimates.

• Sorry but I did not understand 'agricultural needs for walking.' Why would walking produce CO2? – Ram Keswani Apr 3 '18 at 7:21
• Because you have to eat additional food to provide the calories to walk. I suppose you could go idealistic and assume an entirely self-produced plant diet. But the source did not, and based it instead upon various typical diets (typical, organic, etc) and the resource cost of growing and transporting them. I tried to make that clearer, hope that takes care of that :) – JeopardyTempest Apr 3 '18 at 7:58