Published November 12, 2021 - Last Update November 30, 2023 -

Railways, waterways and airways are all part of the essential infrastructure of our society. Of these, aviation is all too often seen as the Big Bad Wolf in the world of climate change. But that picture is based on framing and not on facts. Unfortunately, this picture does seem to influence policymakers. So, let’s unmask the framing, step by step. The effects of doing so may be limited, but it will hopefully lead to the return of justifiable pride in one of human society’s greatest achievements: the conquest of the air.

To start with, let us list three things that are not up for discussion. Number one; climate change is real. Secondly, the contribution that aviation makes to climate effects is also real. Thirdly, making an intercontinental flight will add a considerable amount to your personal emissions footprint.

Taxation

Now, let us discuss a fourth point: tax exemptions on international transport are not a necessity. The exemption from taxes on international transport is a political choice. That choice was made in 1944 with the aim of promoting international contact. The hope was that this would reduce the risk of major armed conflicts.

Of course, the choice made then does not have to be maintained forever, but the discussion about altering that choice should be about the choice. Therefore, do we still consider that the promotion of international contacts is sensible, or do we opt for limitations to our mobility? Of course, a careful consideration of the pros and cons should look at all of the consequences for the world in general as well as for our society specifically.

Relative Emissions

Unfortunately, rather than having the discussion about the pros and cons of mobility, the issue is often framed thus: aviation should be taxed and restricted because aviation is so bad.

To begin with, that is wrong in a relative sense. Passenger ships are the only real alternative for intercontinental transport, and despite their low speed they use seven times more energy per passenger than an aircraft over the same distance.

It does not work for continental transport either. The alternative here is High-Speed Rail (e.g., the French TGV or the Anglo-French Eurostar) which uses as much energy per passenger as an aircraft. A Dutch journalist, Karel Knip, devoted two articles to this in the NRC newspaper in 2018, but after receiving a spade of negative reactions, mostly hate mail, he decided not to discuss the topic anymore.

In terms of climate change, High-Speed Rail only outperforms an aircraft when using electricity generated by nuclear power stations, which is indeed the case with the TGV and the Eurostar.

Even then, at least 9 million passengers per year, so at least 25,000 per day, must use a High-Speed Rail route, otherwise the emissions resulting from the construction and maintenance of the extensive infrastructure, often with many tunnels and bridges, will throw a spanner in the climate change works and an aircraft will still be the better solution. High-Speed Rail is better than an aircraft in just a few situations and even then, the costs involved are extremely high for a very limited climate advantage. See the post ‘HSR-syndrome‘. The latter is permitted of course, that too is a political choice, but the money spent is all but wasted.

Absolute Emissions

The framing used then switches to a different argument: in absolute terms, the contribution is so large that aviation really must be tackled. Aviation is the Big Bad Wolf. If you then investigate this, you will see that the contribution of aviation to global CO2-emissions is about 2%. Not zero, by any means, and certainly something that needs to be addressed.

But even if it is brought back to zero, it has, by definition, little influence. It is therefore not very clever to place aviation on the scaffolds as climate change’s main culprit… at least, not if you really want to do something about the climate change problem.

Emissions Growth

Yes, say the framers, it may only be 2% now, but aviation will grow so quickly that by 2050 perhaps a quarter of all CO2-emissions will come from aviation. If you analyze this, it turns out that the amount of 25% will only be reached when aviation does nothing at all, while all other human emission sources have been reduced by at least three-quarters. And if that happens, the climate change problem is well on track to being solved, including the aviation problem. Because that would mean we have moved from fossil fuel to emission-free electricity as society’s main power source and this will also make aviation emissions free.

Efficiency

The final piece of framing is that aviation must become more fuel efficient and that, just like with cars, you can enforce this by taxing fuel. To say this shows a great lack of knowledge of aviation. Aircraft have a maximum take-off mass that is strictly observed. Even if the fuel were free, aviation would become increasingly more fuel efficient as lower fuel consumption means more space for passengers and cargo on board an aircraft.

This is exactly what happened during my career in aviation: the fuel consumption of civil aircraft decreased from 8.5 liters per passenger per 100 km (Douglas DC-8; my first intercontinental aircraft) to 2.3 liters per passenger per 100 km (Boeing 777; my last one). That is a decrease of more than 70%. Therein lays the problem. Unlike with cars, there is little room for further improvement.

Future

Nevertheless, there is a potential solution. One could choose to limit mobility by making flying more expensive. However, one would also have to make the alternatives equally more expensive, otherwise the results might be disappointing as demand might move to forms of transportation that perform worse than aviation. So, the discussion must really be about whether to limit mobility, not about limiting aviation.

But if you choose to restrain mobility by making air travel more expensive, governments must use the revenue from levies or taxes to make aviation climate neutral. Because aviation does have a problem. High-Speed Rail can run on electricity from nuclear power plants and can also use electricity from other emission-free sources as soon as it becomes available in sufficient amounts. Aircraft cannot do that.

The path to climate neutral flying is through the development of SAF: Sustainable Aviation Fuel. Initially and for short range flights this can be bio-kerosene, already possible now and produced, for example, from Algae or Miscanthus, so that it does not compete with food production. Later this can be hydrogen for these shorter flights, once suitable aircraft and sufficient emission-free electricity to make the hydrogen are available. For longer flights the only option so-far is synthetic kerosene, which could be made when there is more production of electricity from solar, water or wind energy or nuclear power stations than what is needed for other users.

Both SAFs are already technically possible but are still too expensive. If you really care about the future, you should choose to work on stimulating this development, and not on policy making based on framing.

In short: when you work in aviation, you have every reason to be immensely proud. When you are a policy maker, please make wise choices based on facts. If you wish you could have a quick look at the policy options mentioned in the blog post ‘Airway to 2050‘.

Aficionados of numbers and percentages can find background information, sources and detailed examples of the framing discussed above in the pdf
“The Beauty of Aviation – Solutions versus Framing”
first published November 4, 2021, last edited April 22, 2023.

For an analysis of the options to reduce sound annoyance see the pdf
“Sound Exposure versus Sound Annoyance“
first published December 7, 2022, last edited October 4, 2023.