Transport accounts for around one-fifth of global carbon dioxide so our collective choices matter. This chart from Our World in Data, was sourced from the UK Government’s methodology paper for greenhouse gas reporting, widely used by companies to quantify and report their emissions. It shows the comparison of travel modes by their carbon footprint, measured by the amount of greenhouse gases emitted per person to travel one kilometre.
While this work was undertaken in UK, it is entirely relevant in Australia and New Zealand, by applying a little sensibility. Obviously we don't have international train travel and of course Australia's electricity production is the dirtiest in the world so the electricity emissions are a little larger in Australia. In the end however, it doesn't largely change the usefulness of the chart in acting as a useful transport decisioning tool. (Substitute Eurostar for distances over 1000 kilometres.)
No surprises here. You can happily leave this article right now with this knowledge, but to be frank, you probably knew this already. Often travel decisions aren't simple and involve other dependencies like distance, so read on if you want the whole cook book of comparative recipes.
Using a bike instead of a car for short trips would reduce your travel emissions by 75%. Taking a train instead of a car for medium-length distances would cut your emissions by 80%. Using a train instead of a domestic flight would reduce your emissions by 84%.
Over short to medium distances, walking or cycling are nearly always the lowest carbon way to travel. While not in the chart, the carbon footprint of cycling one kilometre is usually in the range of 16 to 50 grams CO2eq per km depending on how efficiently you cycle and what you eat.
What if you can’t walk or cycle, or you need to travel longer distances and can’t take a train? Taking a flight or driving alone are the most carbon-intensive options. Between the two, which is better depends on the distance travelled. If you’re travelling moderate distances - less than 1000 kilometres or a domestic flight - then flying has a higher carbon footprint than a medium-sized car. If the distance is longer - more than 1000 kilometres - then flying would actually have a slightly lower carbon footprint per kilometre than driving alone over the same distance.
There can be wide variation in emissions depending primarily on a) the length of your trip, b) the source of electricity in your local grid, c) the occupancy of public transport and d) in the case of driving — your vehicle and number of passengers.
When driving, your emissions will depend mainly on which vehicle you use and the number of passengers. Driving a small car emits 111 g CO2eq per km while a large 4×4 car emits 200 gCO2eq per km. Adding one additional passenger travelling to the same location would halve emissions per passenger-kilometre.
Some general takeaways on how you can reduce the carbon footprint of travel:
Greenhouse gases are measured in carbon dioxide equivalents (CO2eq), meaning they also account for non-CO2 greenhouse gases and the increased warming effects of aviation emissions at high altitudes.
Image: Unsplash | Dave Kim / Chart | Our World in Data. Information from this article was used under Creative Commons. The original article was written by by Hannah Ritchie. Our World in Data presents the data and research to make progress against the world’s largest problems. This blog post draws on data and research discussed in our entries on CO2 and Greenhouse Gas Emissions and Energy by Hannah Ritchie and Max Roser. This article was first published in May 2017; last revised in August 2020