Fight or flight: the truth behind air travel

As people become more conscious of their environmental impact on the world, there’s been an increased focus on air travel — and over the past year, a corresponding increase in “flight shaming”. Perhaps surprisingly, air travel isn’t a huge contributor to carbon emissions, accounting for only 2.5% globally. So, is it really as bad as people say?

In Ireland, around 40% of total greenhouse emissions come from transport. The largest sources of transportation-related emissions include passenger cars, light-duty trucks, sports utility vehicles, pick-up trucks, and minivans. These sources account for over half of the emissions from the transportation sector. The remaining greenhouse gas emissions from the transportation sector come from other modes of transportation, including freight trucks, commercial aircraft, ships, and trains.

air travel
A table of the energy related CO2 emissions by sector. Image sourced from the SEAI.

At the individual level, the emissions produced by air travel depend on where passengers sit and whether they are taking a long-haul flight or a shorter one. For long haul flights, carbon emissions per passenger per kilometre travelled are about three times higher for business class and four times higher for first class, according to the Department for Business, Energy and Industrial Strategy (BEIS) in the UK. This is because there’s more space per seat, so each person accounts for a larger amount of the whole plane’s pollution. Taking off uses more fuel than cruising. For shorter flights, this accounts for a larger proportion of the journey. And it means lower emissions for direct flights than multi-leg trips.

Carbon emissions from flying are still pretty bad. Generally speaking, air travel is worse than any other mode of transportation. The science is tricky: since there are a surprising number of variables, there’s really no good apples-to-apples comparison. Depending on the make, model, distance, and the number of passengers in your car, driving might be better — or worse — than flying. The same is true with buses.

If you’re driving alone, especially over a long distance, air travel could be better. Yet, on that same trip, if you carpool with three other people, you can get your numbers down by a quarter, making driving the better option. So, it turns out there’s no one-size-fits-all answer. You can’t say “flying is bad, never fly” because sometimes it’s better to fly.

But what are the most eco-friendly ways to travel? Usually, rail is the best option. Trains are among the most efficient and lowest-emitting modes of transport, according to a report by the International Energy Agency (IEA). In particular, urban and high-speed rail hold “major promise to unlock substantial benefits,” said the report, including reducing greenhouse gas emissions, congestion and air pollution. 

Trains make up 8% of the world’s motorised passenger movements, yet use only 2% of the world’s transport-energy demand, according to the IEA. If services performed by rail were instead carried out by planes, cars and trucks, transport-related greenhouse gas emissions would be equal to the CO2 emissions from the entire continent of Africa (that’s as much as the annual carbon dioxide output from 200 million cars).

Electric cars are also a great option. With no tailpipe, pure electric cars produce no carbon dioxide emissions when driving. This reduces air pollution considerably. Put simply, electric cars can give us cleaner streets, making our towns and cities better places to be for pedestrians and cyclists, as well as being far better for the environment during long haul drives. Over a year, just one electric car on the roads can save an average 1.5 million grams of CO2. That’s the equivalent of four return flights from London to Barcelona.

So next time you decide on a journey, weigh your options – if you’re travelling alone for a long journey, a flight may be the better option. If a rail option is available for you, that could be a great way to reduce your carbon footprint. Whatever you choose, be conscious of the environmental ramifications of your trip.

Erica Carter
Erica Carter

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