When I travel, I try to limit my environmental impact. I don't want to refrain from travelling completely, but when I do travel, I tend to favour ground-level transportation over air-transportation, if distances are not too large (e.g., if traveling over-land would take more than three days, I might fly anyway.

A well-filled train usually has a much lower ecological footprint per traveller-kilometer than an æroplane, particularly if the train is hydro-electrical, such as in Sweden. High speed trains and diesel trains are already worse, but still considerably better than flying. But what about ferries? Fuel used by (fast) ferries can be quite dirty. On the other hand, ferries may carry over a thousand travellers, sometimes several thousands.

How does the ecological footprint per traveller of a typical, well-filled ferry compare to the ecological footprint per traveller of an æroplane?

For example, travelling from Stockholm to Warsaw, one might identify four alternatives with a somewhat similar travel class, where all day trains are 2nd class and all overnight accommodation (train or ferry) is with a bed/berth in a shared cabin.

  • flying in an ordinary economy seat
  • by train+ferry via Nynäshamn–Gdańsk
  • by train (almost) all the way via Copenhagen, Hamburg, Berlin (a considerable detour)
  • (only part of the year) by train-on-ferry via Malmö and Berlin (Berlin Night Express)

Which one is the most ecological?

  • Great question! I have been looking for travel search engines with Eco information, and there are one or two (free) for air travel. I think you have missed one possible travel route, the over night train from Malmö to Berlin. And then Berlin to Warsaw. Though I have no real numbers I've used this myself several times, might just be the least eco destructive route.
    – Alendri
    Oct 7, 2012 at 12:14
  • True, I didn't think of that one because it's not operated when I will travel, it's not year-round. I have added it now nevertheless.
    – gerrit
    Oct 7, 2012 at 12:33
  • What travel class? There's a big difference in impact between first class and economy on many modes of transport, due to the different amounts of space you take up
    – Gagravarr
    Oct 7, 2012 at 13:02
  • @Gagravarr, true, I have added information on this.
    – gerrit
    Oct 7, 2012 at 13:07
  • Personally I would like to have the comparable data of any available classes, so I can make a choice and see the difference between them.
    – Alendri
    Oct 7, 2012 at 13:13

2 Answers 2


Emissions figures for ferries are surprisingly hard to find compared to those for cars, trains, and aircraft. The best source I've found for ferries is this report:

Åkerman, Jonas (2008). Klimatpåverkan från utrikes resor ["Climate effects from foreign travel"]. Report TRITA-INFRA-FMS 2008:7. Stockholm: Royal Institute of Technology.

Åkerman looks at foreign travel by residents of Sweden. He sources ferry emissions figures from public environmental impact reports and personal communications from Silja Line and Viking Line, the main operators of ferries between Sweden and Finland. These are the final figures he arrives at for ferries and other major modes of transport:

| Mode of transport |   Average greenhouse emissions |
|                   | (kg CO₂-equiv. / passenger-km) |
| Air               |                           0.24 |
| Car               |                           0.09 |
| Ferry             |                           0.17 |
| Bus               |                           0.02 |
| Rail              |                           0.04 |

There are caveats and significant uncertainties attached to all these figures, but even taking them as order-of-magnitude estimates indicates that the train produces far fewer greenhouse emissions than the ferry.

Estimating the relevant distances for your Stockholm-Warsaw trip with Google Maps gives me:

| Route                       | Distance  | Emissions                   |
|                             | (km)      | (kg CO₂-equiv. / passenger) |
| Air, direct                 | 800       | 192                         |
| Ferry + Rail via Gdańsk     | 570 + 350 | 97 + 14 = 111               |
| Rail via Hamburg            | 1800      | 72                          |

I didn't do the maths for "Berlin Night Express" route, but I imagine it would be similar to the train-only route since the Trelleborg-Sassnitz crossing is a short one.

  • 1
    Interesting! As a side note, I'm surprised by the bus vs. rail figure, considering that rail is often electric and electric rail may be nuclear or renewable, whereas buses are essentially always diesel.
    – gerrit
    Jun 14, 2019 at 12:20
  • It would also be interesting to see how the emissions of ferries are divided between foot passengers, car passengers, and freight sharing a ferry Jun 14, 2019 at 12:26
  • @gerrit Yes, that surprised me too. My guess is that it's skewed by the restriction to international travel, which in the case of buses often means pre-booked charter coaches with high occupancy ratios. Åkerman assumes 70% occupancy for buses which is probably reasonable in this case, but would probably be unrealistically high for a lot of local/regional bus services.
    – Pont
    Jun 14, 2019 at 12:55

Comparing aeroplanes and trains shows that aeroplanes are very much the least ecologically friendly mode of transport. As an example from http://www.seat61.com/CO2flights.htm:

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A site which has some limited data comparing plane, train and car+ferry gives us the following data, but I would assume that the car emissions skew the numbers somewhat, which leads me to believe that the ferry could be the lowest impact:

enter image description here

Caveat: these only take CO2 into account, and there are many other ways transport impacts the environment.

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