Jan Heuberger

One flight from Europe to Asia can produce five metric tons of carbon emissions, which is as much as a single human on an average produces per year. Flying is one of the most unsustainable ways of traveling, but still, the amount of flights and passengers is rising year by year. Considering the Paris Agreement and the corresponding climate goals something must be done. Immediately. Various projects are already underway to find solutions to make flying more sustainable and make a significant contribution to the fight against human-induced greenhouse gas emissions.

The appearance of the new Covid-19 virus has forced the governments of various states to take measures that have had astonishing effects. For example, the decrease in air pollution in China, which has fallen massively since the outbreak of the virus. It is inconsiderate to think that not only air pollution will be improved, but also the emission of greenhouse gases, especially the CO2 caused by flying. Maybe the measurements/lockdown after the outbreak of Covid-19 are a first step in the right direction and can show us what could be possible, in terms of reducing emissions.

But what is already being done to make aviation more sustainable and what impact could Covid-19 have in the future?

Climate change and the rising emissions of greenhouse gases

The Greenhouse effect can be explained as global warming when certain gases in the atmosphere trap heat as long-wave radiation, which is submitted by the earth, short-wave radiation is reflected back to space. The more greenhouse gases are in the air, the more heat is captured in the molecules.

A lot of these greenhouse gases are emitted by humans. Even though these gases occur normally in the atmosphere, the human-caused rapid rise over the last century is problematic.

CO2 is the most anthropogenic released greenhouse gas in the atmosphere. The amount of CO2 in the air today is 40% higher than at the beginning of the industrialization. The causes for this increase are among other the use of fossil fuels, burning of coal, deforestation and large-scale livestock farming. Traveling and transport are human activities with a large fossil fuel demand. Nearly all ways of traveling include the emission of greenhouse gases, especially CO2. The biggest “villain” of low-emission travel modes is aviation.

Why should we avoid flying?

Flying results in the release of a lot of carbon dioxide into the air, as it has a high fuel demand. According to Arunima Malik, who is a researcher at the University of Sydney, 8 % of the greenhouse gas emission results from traveling itself. Looking closer at the fractions, 2% of the traveling related emissions are caused by aviation, which doesn’t seem that much. But if you compare a flight from London to San Francisco with the emission produced by a family car per year, the emission is twice as high for the flight compared to the car, which is significantly more. In the following picture you can see the emissions of different travel options regarding CO2 and other greenhouse gases.

Figure 40.1 – CO2 and Non CO2 greenhouse gas emissions of different means of transport in comparison. https://www.bbc.com/future/article/20200218-climate-change-how-to-cut-your-carbon-emissions-when-flying

The global emissions are still rising, between 2013 and 2018 they increased by 32%, in spite of new, better fuel and more aerodynamic design. Furthermore, the total passenger number is unpredicted to double within the next 20 years and stressing the problem further.

But CO2 emissions are not the only problem caused by flying, there are other substances released with negative effects on the atmosphere, such as water vapor, which is even a stronger greenhouse gas than CO2. Traveling without boarding a plane is thus already a good start to reduce one’s own carbon footprint.

What is the role of the aircraft altitude on the climate impact?

Researchers are trying to reduce the CO2 emission in multiple ways. There are greener fuels, electric engines or more efficient aircraft designs. But according to a study at Imperial College London, there is an easier way, which could help to reduce the impact of flying on the climate. A change of altitude of 2% of all flights by a couple of hundred meters, can already reduce the damage by as much as 59%.

Meant are the airplane contrails, which are occurring when an airplane passes in the sky. Contrails are like an ice cloud around small dust particles. These contrails behave just as normal clouds, they can reflect sunlight and have a cooling effect, or they block the heat reflected from the earth. On average they hold more heat back than they are cooling the earth and thus amplify the greenhouse effect. However, these contrails are only formed in areas of thin atmosphere and high humidity and only last a maximum of around 18h. Therefore, already a little change in attitude can prevent the airplane from producing these contrails by avoiding these areas. The only problem is, that according to the scientist Andrew Heymsfield, to determine which altitudes are beneficial. Finding a way how to measure and determine the optimal heights, represents one of the biggest challenges for the researchers involved.

The CORSIA agreement

In 2016 the members of the International Civil Aviation Organization ICAO have decided on a compensation system for air traffic. The agreement is called Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). This is the first-ever sector-wide carbon-offsetting program.

The aim of this program is to limit the net carbon emission from 2021 until 2035 for international flights between the participating countries. The average of the 2019 and 2020 net emission is used as the reference limit.

If the CORSIA agreement can be fully realized, it might prevent approximately 2.5 billion tons of CO2 emission over the next 15 years, even more, if the limit is reduced.

There are multiple ways for the airlines to cut the CO2 emission. They can choose freely between the following options:

1. Use more efficient aircrafts
2. Find new technologies, which set more efficient flight paths and reduce delays
3. Use sustainable alternative fuels
4. Invest in emission offsets within or outside of the aviation sector.

The program is divided into multiple steps. From 2021-2026 81 nations participate in a first voluntary phase, while the second phase from 2027 until 2035 is mandatory to the participants.

From 2022 every three years CORSIA is analyzed on its contribution to the sustainable development in international aviation and the effectiveness is evaluated. In 2032 there will be the ultimate evaluation of the project and it will be decided, if the project will continue longer than 2035 or if it will be terminated.

Alternative fuels vs kerosene

Since air traffic is expected to continue to grow, the demand for fuels will also increase. Per ton of burned kerosene 3.15 tones of CO2 are emitted. There is therefore great interest in sustainable, alternative fuels. One solution could be renewable energy from air and water or an alternative fuel made from plants, fats or waste.

There are already alternative fuels that are in use but they cannot compete with kerosene in terms of price, weight and required space. Firstly, they are not available in large quantities and secondly, alternatives currently cost up to five times more than kerosene. Furthermore, the cultivation of plants for fuel needs a lot of space, which leads to a competition with the cultivation of food.

However, the cost of fuel is very essential for an airline, as it is one-third of the total cost an airline has. Therefore a way must be found to produce these alternative fuels in large quantities in the future, which will then be available at a competitive price.

Until the goal of sustainability for fuels is achieved, there are other issues to consider. Namely, it must be investigated if and how much the CO2 emission is really reduced. Whether the area under cultivation does not affect the cultivation of food and how much energy and raw materials are otherwise required. These points must be represented in a measurable and comparable value so that it is possible to carry out an evaluation to see whether a contribution to climate protection ultimately is made or not.

The impact of Covid-19

Due to this virus outbreak, the global aviation system is in a crisis, countries closed their borders to reduce international traveling till further notice. More and more flights are canceled and airlines are currently grounded . In the month of March 2020, the international passenger capacity has already been reduced by 33%. This could maybe be a chance to reduce the attractiveness of flying. Nowadays flying can be extremely cheap, for example, a ticket from Zurich to Spain can be cheaper than a train ticket within Switzerland from Zurich to St. Moritz. Due to the lost income, some airlines are facing bankruptcy, this could lead to more expensive flights as the airlines will not be able to execute flights if they are not profitable. High ticket prices could make passengers question and debate the need for a flight for their next vacation. The fear of a virus and other diseases could also prevent people from wanting to travel in such crowded transportation to exotic places. The current lockdown shows that technologies as teamwork softwares and video conference meetings work even for large organisations e.g the EU and others and made traveling unnecessary. This could lead to less executive traveling as companies can save money using the now proven tools available. However only time will tell if these assumptions will come true.

References: 

1.  https://www.beobachter.ch/umwelt/forschung-innovation/biotreibstoffe-antrieb-der-zukunft  Stefan Bachmann, zuletzt aktualisiert 31.5.2012
2.  https://www.klimaschutz-portal.aero/klimaneutral-fliegen/alternative-kraftstoffe/ Aufgerufen 6.4.2020
3. https://www.bbc.com/news/science-environment-49349566 24th August 2019
4. https://edition.cnn.com/travel/article/airplane-contrails-climate-change-science-study/index.html Francesca Street, Updated 16th February 2020
5. https://www.bbc.com/future/article/20200218-climate-change-how-to-cut-your-carbon-emissions-when-flying Jocelyn Timperley, 19th February 2020
6. https://eu.usatoday.com/story/news/2018/12/26/flying-bad-environment-heres-what-do/2350488002/  Elizabeth Weise Updated 15th December 2019
7. https://www.icao.int/sustainability/Documents/COVID-19/ICAO_Coronavirus_Econ_Impact.pdf
8. https://www.tagblatt.ch/international/luftverschmutzung-in-china-massiv-gesunken-diese-satelliten-bilder-zeigen-die-einzige-gute-seite-des-corona-virus-ld.1199576