Thursday, 22 January 2015

Green Travel - is where you go rather than how you get there

There are two parts to green travel - the travel bit and the staying there bit. It's a good rule of thumb that flying is heavy on carbon emissions, though it isn't so much the flying as such, it is the distance you can go when you fly. You might average 60 mph in a car, or even 70 mph on motorway.  A Boeing 747 cruises at about 550 miles per hour so you can get a lot further in the same time.

The table below shows carbon emissions from journeys by air, road and rail.

ModegCO2e/kmExample there and back
Air long haul/passenger (economy)151London - Johannesburg 9000km x2
2,800 kg
Air short haul/passenger (economy)158London - Berlin, 940km x2
500 kg
Car (medium)177Cambridge - York 250km x2
88 kg
National rail/passenger48Cambridge - York 250km x2
24 kg
Eurostar/passenger12Cambridge - London (National) 90km +
London - Paris (Eurostar) 500km x2
20 kg
Data from Government conversion factors for Greenhouse Gas Reporting

For comparison, the average UK person generates 25 kg CO2e/day (9.1 tonnes/year)*.  That means one return flight to Jo-burg is equivalent to 112 days worth of carbon emissions for the average UK person -  nearly 4 months.

By the way, a typical hotel stay is another 30 kg CO2e/room/night (from ecometrica). So for a trip to Paris, the hotel will dominate but for a trip to Jo-burg, the main bit is definitely the travel.

You might decide to go anyway and carbon-offset your journey - see Carbon Offsetting - does it really work. But  that post is a bit old so the costs have changed. Climate Care now charges about £7.50/tonne CO2e. Offsetting the Jo-burg trip would cost you £20.

Because of the carbon emissions and also for other reasons - like we hate airports and we don't drive - I and my beloved have used the train for almost all of our holidays for at least the last 5 years.  You can hear about our experiences and other aspects of green travel next Thursday at the Fort St. George pub on Midsummer Common. The event is Climate Friendly Holiday Choices organised by Cambridge Carbon Footprint. (By the way the Fort. St. George footbridge is closed so you will need to cross the river somewhere else).

* UK emissions 581.1 mt CO2e in 2012 ( pdf), UK population 63.7 million in 2012 (ONS)


  1. It's good to see updated figures all in the same place - thanks. Do the air travel emissions include 'radiative forcing'? I believe understanding on this has changed, and we should now assume that emissions at high altitude have around double the global warming potential of emissions at sea level.

    1. Yes they do include RF - it seems to about double the numbers, as you say.

  2. Nicola,
    I'm struck by the very low figure for Eurostar. In principle, the faster you go, the more energy you use. High speed trains will therefore be using more energy than low speed ones, all other things being equal. But that's not how it appears in your table.

    Could it be the low carbon score for Eurostar is because French electricity is mostly nuclear and therefore has a very low carbon intensity?

    1. Yes, I was surprised too. But Eurostar is exclusively electric and the French electricity is low carbon. Also possibly Eurostar trains have higher average occupancy than normal National Rail.