¿What is the Carbon Footprint of Sea Freight and Ferries?

It is quite easy to find the carbon footprint of air and land transport, but what about maritime transport? In this article we explain what impact on CO2 emissions you produce if you or the products you buy use this means of transport.

The carbon footprint for a passenger on a ferry is 19 g CO2/km. If a car is also boarded, the footprint increases to 130 g/km. For freight ships, between 7 and 45 g CO2/km are emitted per tonne of cargo. For cruise ships, each passenger produces 10,700 g CO2/hour.

Ship type Carbon footprint
Ferry 19 g CO2/km passenger
Freight ship 7 - 45 g CO2/km tone
Cruise ship 10,700 g CO2/hour passenger

To give you an idea of how the comparison with other means of transport stands, a passenger on a domestic flight produces 255 grams of CO2 per kilometer, by car 181 g CO2/km and by bus 28 g CO2/km.

So on a journey from Barcelona to Palma de Mallorca, a passenger's carbon footprint, measured in kilos, is:

  • By ferry, without vehicle: 4,6 kg CO2
  • By ferry, including vehicle: 31,6 kg CO2
  • By plane: 55 kg CO2

If you want to make more comparisons between means of transport or for other distances, you can use our Carbon Travel Calculator.

It is important to note that these figures may vary depending on many factors and the sources consulted. Below we explain in more detail the carbon footprint for each type of ship, as well as other comparisons so that you can get a better idea of what all these figures mean.

Ferry

Balearia Ferry

Balearia Ferry. Photo by Manolo Gómez en Flickr.

As we mentioned, the carbon footprint for a passenger travelling by ferry is 19 grams of CO2 per kilometer travelled. This figure comes from the UK Government (source), and is also the one we use for our Carbon Footprint Calculator, since apart from considering it a serious and impartial source, it also gives figures for other means of transport, thus allowing a fairer comparison.

If we look at other sources, according to a report by the Intergovernmental Panel on Climate Change (IPCC), the carbon footprint of a passenger ship ranges from 15 to 150 grams of CO2 per kilometer and passenger, which also fits our reference figure.


Why does the IPCC give such a wide range?

There are many factors to consider, among others:

  • Efficiency of the ship's engines
  • Ship aerodynamics
  • Class you are traveling in
  • Possibility that a vehicle has also been shipped
  • Ship size

It could be a ferry like this one:

Small ferry

Small ferry used for passenger only. Photo by HS Spender en Unsplash.

Or a much larger ship, which also transports cargo trucks, so the emissions produced by the ship are spread between passengers and cargo and result in a much smaller carbon footprint per passenger.

Big ferry

Large ferry used for passenger and cargo. Photo by stroller en Pixabay.


As a last source, we can look at Balearia's 2017 annual report, where they also specify the average carbon footprint of their fleet. According to this report, for every ton of cargo 97 g CO2/km/km are emitted. Assuming that each passenger and their luggage weigh 100 kg, this gives a carbon footprint per passenger of 9.7 g CO2/km/km.

This figure is somewhat lower than those from previous sources. This could be due to the calculation system used by Balearia, and/or more efficient boats.


Below you can see in a table the summary of the carbon footprint of passenger ships according to the different sources:

Source Carbon footprint
(g CO2/km passenger)
uk.gov 19
IPCC 15 - 150
Balearia 9,7

Freight ship

Freight ship

Freight ship moored in the port of Hamburg.. Photo by Julius_Silver en Pixabay.

Due to the large amount of goods that can be transported by a cargo ship, sea transport is the least polluting means of transporting goods, except for the electric train as long as a large percentage of the electricity is produced with renewable energy.

If one starts researching the carbon footprint of this type of ship, the few figures that can be found will be very different. As always, one has to be careful about who gives the figures, as they may be made up if there are hidden interests. That is why we are relying again on the data provided by the IPCC.

According to this study, a transoceanic container ship has a carbon footprint of between 7 and 25 g per kilometer and ton transported.

For ships that transport containers over shorter distances, such as from the Iberian Peninsula to the Balearic Islands or the Canary Islands, the carbon footprint is between 15 and 45 g per kilometer and ton transported.

In this case, the range of values is not only due to the size of the ship and the cargo it can carry, but also because of other factors such as whether it carries refrigerated cargo and how efficient the engines are.

Practical example

Bananas

Transporting a kilo of bananas has a different carbon footprint depending on their origin.. Photo by TheDigitalArtist en Pixabay.

To get an idea of what these numbers represent, let's say we live in Barcelona and buy bananas from Costa Rica. Taking a value of 15 g CO2 per kilometer and ton transported for the transoceanic ship, it comes out that each kilo of bananas has a carbon footprint of 138 g CO2 (only for the 9,200 km of maritime transport, not including neither production nor possible land transport, among others).

If we buy the bananas from the Canary Islands, taking an average value of 30g CO2 per kilometer and ton transported, it comes out that each kilo of bananas has a carbon footprint of 72g CO2 (only for the 2,400 km of maritime transport, not including neither production nor possible land transport, among others).

In a more extreme example, such as buying apples from New Zealand, which is 20,300 km away, the carbon footprint for each kilo of apples is 304 g CO2.

Comparison with other means of transport

Taking again the IPCC data as a reference, below we show you what is the CO2 footprint of maritime transport compared to other means of freight transport.

As you can see, for each means of transport there is not a single figure but a range of values between a minimum and a maximum. This is due to all the factors that influence the calculation of a carbon footprint.

Chart produced by Travelinho from IPCC report data, page 610.

Cruise ship

Cruise ship

The carbon footprint of a Cruise ship is 10,700 g CO2/hour (257 kg/day). Photo by Peter Hansen en Unsplash.

The pollution produced by cruise ships is an issue that many people already know from the news that has been published in recent years: some cities have taken measures to limit the number of cruise ships moored in their ports and thus be able to better control air quality.

A cruise ship is in fact a floating city with its own electricity generation. Even when it is moored it continues to generate electricity, being this form of generation much more polluting than land-based generation.

Thus, cruise ships emit very harmful gases such as nitrogen oxide (NOx) or sulfuric oxide (SOx). However, in this article we focus only on greenhouse gas emissions.

Because the cruise ship continues to pollute when it is moored, we have taken as a measure to calculate the carbon footprint the kilos of CO2 per day, instead of per kilometer. To do this, we have used myclimate.org's CO2 cruise calculator.

Considering a cruise ship of between 1,000 and 2,000 passengers in size and a standard cabin, the carbon footprint per passenger is 257 kg CO2/day, or 178 g CO2/minute.

Traveling in a suite cabin the footprint is even higher, as these cabins occupy more surface area and have more amenities. The carbon footprint then rises to 320 kg CO2/day, or 222 g CO2/minute.


To put these figures into perspective, it is worth noting that each Spaniard emits an average of 6 tons of CO2 per year. In addition, to avoid exceeding 2°C of global warming, each one should emit a maximum of 2.3 tons per year. Thus, a 9-day cruise is equivalent to more than a third of the Spanish annual average and the quota that each one should emit in a whole year.

If you are interested in calculating more accurately the CO2 footprint for a cruise, you can visit the myclimate.org website where they offer their tool for free, as well as the possibility of offsetting your carbon footprint.


We hope you found the article informative. If you have any questions or want to make a comment, you can do it on Facebook, Twitter or you can contact us directly.