Flygskam or SUVskam?

A recent EIB poll showed a majority (62%) of Europeans favour banning short haul flights. If only it were that simple to reduce emissions.

Updated August 2022 to reflect Boeing 737 now on Dublin-Kerry and new ATR on Dublin-Donegal

Like demonising diesel when it emits less CO2/km than petrol (whilst we wait for zero emissions vehicles to fall in price), banning short haul flights will push those who need to fly short haul into single occupancy cars – where rail is not an option.

This post is a longer version of the tweet shown below that generated quite a few questions, so thanks to all for their interest and here goes with the sources etc.

On an individual basis, one person flying to Donegal emits less CO2 than one person driving economically in a VW Golf 1.6TDCI diesel. 

My calculations and sources

  • Golf 1.6TDCI at 5L/100km and 3.17kgCOe per litre Well to Wheel (5% bio) is 15.85kg/100km
  • Dublin Airport to Donegal Airport by road is 285km – Google Maps
  • 2.85 x 15.85kg/100km = 45.17kg x return = 90.3kg CO2e
    • 5L/100km from 50,000+km in my 141 VW Golf Diesel trip computer. Your mileage will vary and most will be consuming far more fuel per 100km.
    • Other real-world sources are available on the internet, but broadly speaking you will find your car’s L/100km or MPG on the dashboard trip computer.
    • Dublin-Donegal round trip by scheduled airline service is 58.4kgCO2e – Source ICAO calculator (2020)
    • One way it’s 45.17kg from the car vs. 29.2kg from the plane per seat (2020)
  • Yes, if only one person travelled then the entire flight emissions would be 853.6kg (now 518kg due to newer aircraft in 2022) but that’s not the reality. Cars have an average load factor of 1.5 people (30%) and airlines over 90% or 72 seats x 90% = 65 PAX (or 43 PAX at 60% load factor).
  • Basically, once there are 18 or more passengers on board (25%), it is better to fly together than travel alone by car.

The calculation is based on best available data, if you have a better source please comment below and I will amend.  The aim is to illustrate the choices available to individuals and what might happen if we ban all short haul flights where rail is not available.

I am not saying flying is greener than driving, it’s not; the faster you go the more you energy you use and the more your journey emits. The difference here is in load factor.

Yes, it’s too simplistic to show point to point when we often travel via other locations, but it helps to make the point clearer. See a more detailed Dublin-Tralee example below (updated August 2022 to show Boeing 737). 

So my key point was to be careful what you wish for when banning short haul flights. If all passengers chose to travel alone by car instead (as I would for work) the unintended consequence would be more emissions, not to mention issues like increased driver fatigue resulting in accidents.

Total emissions from a round trip flight is 853.6kg (now 518kg) vs. let’s say (at default 60% load factor) 43 sole occupancy car journeys at an economical 1,942kg CO2e.

Sample comparison between Dublin and Donegal as of August 2022 with ATR on Dublin-Donegal and 333gCO2/kWh after a firly windless 2021.

Flygskam (shame) vs SUVskam

The IEA recently published a blog “Growing preference for SUVs challenges emissions reductions in passenger car market”

The impact of its [SUV share] rise on global emissions is nothing short of surprising. The global fleet of SUVs has seen its emissions growing by nearly 0.55 Gt CO2 during the last decade to roughly 0.7 Gt CO2. As a consequence, SUVs were the second-largest contributor to the increase in global COemissions since 2010 after the power sector, but ahead of heavy industry (including iron & steel, cement, aluminium), as well as trucks and aviation.

The growth of SUVs dwarfs the growth in emissions from other sectors including aviation:

IEA, Change in global CO2 emissions by energy sector, 2010-2018, IEA, Paris

Fly vs rail vs EV

I used an old slide in replying to some of the questions on Twitter, amended below with feedback from @CillDar – thank you. The slide was used in training to provoke debate and get participants to do the calculations, even if only on the back of an envelope.

Corrected distances and updated factors and again in 2022 to include bigger faster jet aircraft. :

Dublin Kerry showing increase emissions when flying vs driving alone due to larger faster Boeing 737 emitting four times as much as ATR in original comparison.

Any specific journey will have its own characteristics so we shouldn’t damn or promote any one mode, the fact is all modes have a use to someone at certain times.

To those saying Dublin-Kerry by plane is parish pump (pork barrel) politics at its worst, I’d ask you to consider how working from home in Kerry can allow workers to reside, work and spend their income in Kerry whilst being able to commute to Dublin same day using a scheduled airline. I’ve worked same day by rail to Tralee, it was fun but not very productive.

To those who say their electric vehicle can beat these figures… fine, but take a look at Tesla’s range and you will see their electric SUV’s are significantly less efficient than their cars.

[Update 1/8/20: Yes, I am anti-SUV, too heavy, too tall and too dangerous unless needed for towing, commercial work etc. Tesla’s I admire and I’d love, if they just used switches instead of touchscreens, programmable switches per BMW i3 for me for now].

My original point was and is, that shaming those choosing SUVs would be a far more effective online campaign for humanity than #Flygskam in reducing the growth in GHG/CO2e emissions globally.

Update 10th January 2022 from IEA

Record SUVs sales in 2021 highlight need for policy action to tackle emissions
Global sales of SUVs have proven very resilient throughout the Covid-19 pandemic, growing by over 10% in 2021. We estimate that SUVs accounted for more than 45% of global car sales in 2021, setting a new record in terms of both volume and market share, according to our recent commentary.
While there are also more and more electric SUVs on the market, the vast majority of SUVs on the world’s roads today – over 98% – still rely on internal combustion engines. SUVs are heavier and consume around 20% more energy than a medium-sized car. They rank among the top causes of energy-related carbon dioxide (CO2) emissions growth over the last decade. In 2021 alone, the global fleet of SUVs increased by over 35 million, driving up annual emissions by 120 million tonnes of CO2.
To address these emissions trends, government policies, especially fiscal measures, should support a quicker shift towards electric vehicles while providing incentives for the early replacement of SUVs that run on fossil fuels. Even as SUVs increasingly electrify, policy makers should keep an eye on the average size of vehicles. Some governments have already started introducing relevant measures, such as France and Germany, which have put a tax on large and high-emissions cars like SUVs.   Read the commentary by Chief Energy Modeller Laura Cozzi and Energy Modeller Apostolos Petropoulos.

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