Saturday 14 August 2010

Oh… I wasn’t expecting that.

So, this week, I've talked about about my holiday and how good it was to take the car and ferry rather than flying.
Then I thought I'd work out the carbon footprint of both and see how much I saved, to nicely round off my blog week...

CO2e (tonnes)
Car (Eire)6200.16
CO2e (tonnes)
Car (UK)6600.17
Car (Eire)6200.16

OK, so the numbers are only fractionally different, and are based on one set of calculation engines I found on the web. But it does highlight the difficulty of making decisions when the information is not readily available or not actually embedded into our daily decision-making processes. I was pretty gutted when I did these calculations last night.

I can rationalise it. Possibly overall, a ferry lasts longer than an airplane and so the embodied CO2 is less than the plane journey. Maybe the full end-to-end infrastructure of air-travel is overall more damaging than car / ferry travel. Possibly the fact that we have to hire a car in Ireland if we don’t take our own makes a difference. The simple truth is that I just don’t know. And we, as individuals, as societies, cannot make proper decisions unless all the facts are in the public domain and fully transparent.

So, what will I do next year? I’m inclined to still do the ferry / car journey again – it was certainly a better experience for me. The rest of the family may feel differently. We’ll have to see.

Notes: Carbon Footprint measured in tonnes CO2e. Flight & Car carbon footprint measured at Flights are return Stansted to Dublin and include multiplier for radiative forcing. Rail is return Norwich to Stansted. Ferry is return Holyhead to Dublin. Ferry emissions from


  1. Lovely posts this week Jon, enjoyed yesterday's and those solar radiators! That's a shocker about these figures! Hmmmm...

  2. Hi Jon,

    As far as I can tell from the calculators you used, the flights, rail and ferry are per person, but the car is per car (because it uses little more gas with 4 people in a car).
    Thus for a family of 4 this would work out as:
    flights 1.32
    rail 0.08
    car 0.16
    total 1.56

    ferry 0.904
    car 0.17
    car 0.16
    total 1.234

  3. Dear Jon,

    Data is not my strong point, however as I remember from the Carbon Conversations "text" book there is a big difference between ordinary and high speed ferries.

    Which one did you cross on?

    All the best,