Blogbeitrag zum Nachhaltigkeit beim Fliegen - Artenschutz to Go

Is sustainable air travel possible?

As many might know, you book a flight for an upcoming vacation or for a business trip and are plagued by a guilty conscience or even receive negative comments from those around you. There is even a term for this feeling, the so-called flight shame. Many people ask themselves whether it is not enough to make their everyday consumption more sustainable or to generally establish more awareness for the environment. After all, air travel has a small share in global warming and even these emissions can be offset by means of CO2 compensation. But is this really a sustainable solution?

for Thought

According to a study by Manchester Metropolitan University, air traffic contributes 3.5 percent to climate change.14 The most important greenhouse gas emissions are carbon dioxide, nitrogen, and the effect of condensation trails. Additionally, soot, aerosol and sulfate aerosol particles are among them. CO2 accounts for only 1/3 of the climate impact, while 2/3 is due to so-called non-CO2 related factors.1

CO2 is a greenhouse gas and thus has a warming effect on the climate. 2 Nitrogen, oxygen and solar radiation produce ozone, which is also a greenhouse gas.3 Whether ozone protects or harms us depends on the layer of air in which it is found. The ‘ozone layer’ at an altitude of about 15-50 kilometers protects us from the sun’s dangerous UV-C radiation and mitigates the slightly less dangerous UV-B radiation. Aircraft, however, travel at an altitude of about 10 kilometers. The nitrogen emitted there acts as a greenhouse gas and, in high concentrations, can also have health effects.4,5,6

Condensation trails are formed from water vapor that cannot be completely absorbed in the layer of air that is about -40 degrees Celsius cold. They can have a cooling effect by reflecting sunlight directly back into space. Conversely, they can have a warming effect too, similar to greenhouse gases, by preventing the heat rays from re-entering space. However, it is clear by now, according to the study, that the warming effect predominates.6

Air travel is one of the most climate-damaging ways to get around.

For example, the flight route from Frankfurt a.M. to the Maldives with a return flight (16,000 km) emits more than five tons of CO2. In comparison, one can drive more than 25,000 km in a mid-range car (7l/100km).7 To ensure that the Earth does not warm up by more than 1.5 degrees, the annual CO2 budget of a human being is 1.5 tons of CO2 per year. However, a flight from Düsseldorf to New York already emits 2.8 tons of CO2 equivalents per person and thus exceeds the budget by almost double.8

A widely used option to reduce the emissions caused by flying is the so-called CO2 compensation. This involves calculating the CO2 emissions of a flight, for example. It is then determined how much it costs to compensate for this CO2 elsewhere, for instance by donating to climate protection projects for renewable energies or reforestation. Prices vary from provider to provider, since other factors are taken into accounts, such as non-CO2 effects, flight altitude, and stopovers. When choosing a provider, we should look for reputability. Such providers would first advise their clientele to reduce or avoid emissions before offsetting them. In addition, it is important to consider whether these projects would not have been carried out anyway, i.e. even without compensation and whether in the end the amount of CO2 really saved is the amount that one would like to compensate. Therefore, providers should make it clear how exactly they control or guarantee these aspects.9

Another way to reduce emissions from air travel appears to be the development of more environmentally friendly aircraft. Electric aircraft, hydrogen-powered aircraft, biofuel and synthetic kerosene are currently the subject of research. Electric aircraft are electrically powered and emit no CO2, nitrogen, water vapor or soot. However, they are not an alternative to traditional short- and long-haul aircraft due to low energy performance.

Hydrogen-powered aircraft use hydrogen as a propellant instead of kerosene and are therefore CO2 neutral and emit no soot particles. However, they also emit nitrogen and water vapor. The most problematic aspect of this type of aircraft, however, is the lack of space, since hydrogen requires up to four times more volume than kerosene. As a result, the tanks have to be stowed differently, meaning that aircraft would have to be redesigned all over the world.

Biokerosene is not obtained from fossil sources such as petroleum, but from renewable raw materials such as rapeseed oil and palm oil. Less CO2 is emitted during production and, according to a study, up to 70% fewer soot and fine dust particles are emitted. However, water vapor is still emitted and nitrogen emissions remain the same. Biokerosene is already used by some airlines, but so far it is only allowed in combination with conventional kerosene. It is a growing market, but it must be taken into account that the large areas of land needed for it could convert intact ecosystems such as rainforests into monocultures. (see blog post: Palm oil)

Of all these concepts, only synthetic kerosene seems to be a realistic and feasible alternative. It is also called power liquid. For this, CO2 is first filtered out of the air, which is then split with the help of electricity from renewable energies and water vapor. Hydrogen and carbon monoxide are produced. Finally, liquid fuel is produced through synthesis. According to the German Aerospace Center, significantly less CO2 and soot particles are emitted. However, suitable production facilities and further renewable energy sources still need to be developed for this promising method.

Another feasible method to reduce emissions by up to 25% is the optimization of flight routes. The idea behind this is to fly around harmful air layers, since emissions do not have the same effect or are harmful in all air layers. This means that emissions can be reduced even if the optimized flight route would require more time and even more kerosene.8
Der richtige Treibstoff ist eine zentrale Frage bei der Entwicklung nachhaltigerer Flugzeuge. © Jose Lebron on Unsplash
The right fuel is a key issue in the development of sustainable aircraft
(c) Jose Lebron on Unsplash
Der Erhalt unserer Korallenriffe hängt stark davon ab, dass wir die Klimaerwärmung stoppen.
The preservation of coral reefs depends heavily on stopping global warming

The Price Question

Emissions from aviation contribute to global warming. The most common effects of climate change include sea level rise, species extinction, and coral bleaching.

This results in flooding, which mainly affects islands and countries with shallow coasts. Furthermore, the oceans absorb a considerable amount of CO2, but an increased concentration in the sea leads to a lowering of the PH value. The over-acidification affects the life of corals, snails and mussels.10,11

The warming of the water also leads to coral bleaching. All this has consequences for the entire ecosystem associated with it, since corals, for example, serve as the food basis for many marine animals, and thus the habitat conditions are changed. Marine animals migrate to other areas or may even become extinct. Ultimately, dwindling fish stocks also affect the food supply for humans.12
For animals on land, the situation is similar; due to changing habitat conditions, animals will have to migrate, adapt or become extinct. A study by WWF and the University of East Anglia in the UK found that around half of all animal and plant species will become extinct by 2080 in important natural regions such as the Amazon rainforest if man-made emissions continue as they are now. Even if the Paris climate agreement’s minimum target of the 2.0 degree limit is met, one in four animal or plant species in these regions would become extinct.13

But climate change also affects us, humans, directly, for example in the form of increased tick proliferation and immigration of non-native mosquitoes that transmit diseases. Allergy sufferers also feel the effects of climate change, as the amount of pollen increases in northern regions. Furthermore, the pollen season starts earlier and ends later.10


Flying without a guilty conscience is therefore not yet possible. There are already some initiatives, but it will take some time before they are fully developed and tested. So what can you do now? The first step is to try to fly as little as possible. That means short-haul flights and domestic trips should be made by train or bus. As we have all just learned in the current times, entire business trips can be replaced by video conferences.

Perhaps we can also change our perspective on travel in general and ask ourselves what we hope to get out of the trip. Beautiful landscapes and regions are right on our doorstep, even more than we could ever look at. Of course, that’s not to say we can never travel or even fly again. However, we could consider it as something special again and then do it perhaps once a year, instead of twice. The flights that are still taken can be compensated for by CO2 offsetting, but this should not be seen as a free ride. The compensation saves CO2 elsewhere, but there is still an environmental impact due to the released emissions.

As always, being more sustainable or conscious doesn’t have to mean completely giving something up. But we can gain a new perspective on things and thus enjoy them with more respect and awareness.
Louisa Schroeter
Louisa Schroeter

Volunteer from the Nepada editorial team

provides insights into sustainability in everyday life
Our “Species protection to go” contributions make no claim to be completeness, but merely provide insights for a more conscious and more sustainable way of dealing with our planet. Together we can do a lot better, but we can’t do everything right straight away. Would you like to share more insights on this topic? Or do you have any critical comments? Then feel free to drop your comment.