Which factors influence the flight of aircraft

When will aviation go green?

The latest report by the Intergovernmental Panel on Climate Change made clear how difficult it is to achieve the climate target of 1.5 degrees. This goal can only be achieved with great effort. We have to turn almost all areas of life inside out. "How we live, eat, move around," explains climate researcher Niklas Höhe from the NewClimate Institute.

If the remaining CO2 budget for the climate target is distributed equally across all people, then each should not emit more than two tons of CO2 per year. Flying becomes a big problem.

The growth of global air traffic can no longer go on like this. "We also have to completely replace fossil fuel with fuel from renewable electricity and have to ask ourselves which flight is still necessary," said Harry Lehmann from the Federal Environment Agency (UBA). "We have to ask ourselves: How can I improve my transport balance? Going to the disco on the island at the weekend is certainly absurd," Lehmann told DW.

It is no longer possible to continue like this

Magdalena Heuwieser from Stay Grounded, a global network to reduce air traffic, agrees with Lehmann in principle. It describes the dilemma in which environmentally conscious people also find themselves. "Flying is a very difficult and uncomfortable subject. For many, flying is now normal. It is also a status symbol," says the climate activist. "But now it's about: How do we get the climate crisis under control? Do we actually have to change our way of producing and living and also rethink our type of mobility?"

Today, air traffic accounts for more than five percent of global warming and is the fastest growing cause of greenhouse gas effects. An end to this development is not yet in sight. Aviation experts and politicians have also recognized the problem and are alarmed.

The record temperatures in the German summer "have shown what is very likely to await us if we do not act decisively to limit the progression of global warming to the 1.5 degrees Celsius urgently required by the Intergovernmental Panel on Climate Change," said the Environment Minister of North Rhine-Westphalia. Ursula Heinen-Esser (CDU), at the start of the international conference for sustainable aviation called Greener Skies Ahead in Bonn.

Rudolf Doerpinghaus, President of the International Association for Sustainable Aviation (IASA) and organizer of the conference, predicts changes in the aviation industry due to climate change. If aviation does not react in time, "it will hit us like the diesel scandal will hit the auto industry," warns the expert.

Climate-friendly fuels from wind and solar power 

The aviation experts at the conference see the fastest possible replacement of fossil fuels with synthetically produced fuel from renewable electricity as an important step out of the climate dilemma. The development of electric aircraft, on the other hand, is still in its infancy. According to experts, airplanes powered by batteries will not help to significantly reduce emissions in aviation over the next two decades.

The production of kerosene from electricity has been tried and tested and is technically not a problem. With the help of electricity from wind, solar or water power, hydrogen is produced from water in an electrolysis process in a climate-friendly manner and, in a second step, synthetic oil and kerosene are generated by adding CO2 from the air.

These oils, which are produced using the so-called power-to-liquid (PtL) process, are similar to petroleum and can be used in aviation without any problems. Experts see the production of kerosene directly from biomass as no longer trend-setting because of the poor climate balance and high land consumption.

According to experts, the PtL fuels can be produced cheaply in large quantities, especially in countries with a lot of sun, wind and hydropower. In the Norwegian industrial park Heroya, for example, the industrial production of climate-neutral oil is to begin in a larger facility from 2020.

If the fossil fuels in aviation are given an adequate CO2 price, such systems would be profitable in many other countries. The fuels would then be globally competitive with oil.

More on this: Climate-neutral oil from Norway from 2020

How can the additional greenhouse effects be avoided?

Air traffic at high altitudes represents a particularly large and additional climate problem. In addition to CO2, there are additional greenhouse effects from contrails, veil clouds and ozone. With current air traffic, these additional effects have a climate impact that is about twice as high as that of carbon dioxide. In other words: for every ton of CO2 there is also a climate effect that corresponds to the emission of two tons of carbon dioxide. These climate-relevant additional effects also arise with climate-neutral kerosene.

With climate-optimized flight routes, however, the negative additional effects of flying can also be significantly reduced and "even turned into the opposite", says the professor for sustainable technologies, Stefanie Meilinger, from the Bonn-Rhein-Sieg University of Applied Sciences.

For example, if the sun is high in the sky during a flight, radiation can also be reflected back into space through contrails. Many factors influence whether air traffic has a warming or cooling effect: does the flight take place during the day or at night? What about the humidity and how high does the plane fly?

More on this: How does climate protection work with optimized flight routes?

In a large-scale study, Meilinger developed a corresponding optimization system for flight routes for Lufthansa Systems in collaboration with the German Aerospace Center (DLR) and the German Weather Service. According to experts, it could be introduced in the next few years.

The avoidance of climate-warming cloud formation has the greatest potential for climate protection. It would also be possible "to close particularly climate-damaging flight routes for air traffic," says Urban Weißhaar, flight route expert at Lufthansa Systems. But a reward system for choosing climate-friendly flight routes with the help of a price advantage would also be conceivable, according to Weißhaar. Airlines that then choose these routes and take a little detour would be rewarded for it and would have to pay fewer fees.

Expansion before climate protection

Actually, the UN aviation organization ICAO should develop measures for climate protection. But the concept introduced two years ago continues to rely on an unchecked expansion of air traffic without limits. It does not provide a strategy to completely replace fossil fuels and reduce the additional greenhouse gas effects of aircraft at altitude.

ICAO meeting in Montreal (2016): Expansion instead of climate protection

The agreement was "unambitious", emphasized Peter Liese (CDU), the responsible rapporteur in the European Parliament for the inclusion of air traffic in emissions trading (ETS). "This does not reduce the real emissions at the source," says Liese. "This agreement will not reduce a drop of kerosene," agrees Bill Hemmings of the European environmental organization "Transport & Environment".

With its concept "CORSIA" ("Carbon Offsetting and Reduction Scheme for International Aviation"), the ICAO wants to offset a very small part of the greenhouse gas emissions through climate protection projects from 2021 onwards, but in total accepts a strong increase in emissions.

The Federation for the Environment and Nature Conservation Germany (BUND) and five other environmental associations are therefore calling on the German government not to agree to the proposal and to express reservations about the agreement. CORSIA stands in "clear contradiction to the goal of the Paris climate treaty to limit global warming to well below two degrees, as well as to the EU climate protection target of at least 40 percent greenhouse gas reduction for 2030", according to a recent letter to the Ministry of the Environment.

How can air traffic be reduced?

So far, air traffic has not paid for the climate damage, is subsidized worldwide and is exempt from taxes. In Germany, these subsidies are around 12 billion euros, according to the UBA.

Hansjochen Ehmer, aviation researcher at DLR, does not consider the internationally agreed tax exemption for kerosene to be helpful or timely. He argues that the so-called external costs should also be borne by aviation, "we will internalize the external costs. This then naturally applies to all modes of transport on the same basis."

If the costs for damage from air traffic were included in the ticket prices, air traffic would become more expensive again and other means of transport would be significantly cheaper in comparison. Then fewer people would fly just to save money instead of taking buses and trains. Arne Fellermann from BUND also thinks a general ban on short-haul flights in Germany is conceivable. In this way, the set climate targets could be achieved.

Protest against airport expansion in London

The international network "Stay Grounded", to which the BUND belongs, not only demands the abolition of tax privileges. Rather, it would have to be invested in the expansion of night trains so that longer distances can be better covered by rail without using the plane.

In addition, the network is calling for airport projects around the world to be halted. Politics and companies should promote an economy of short distances and advertising for air traffic should be banned. The climate activists see the bans on tobacco advertising as a role model in order to better protect the health of citizens.

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