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The environmental impact of air transport

The environmental impact of air transport

The Swedish transport sector needs to be fossil-free. Over the past 40 years, air transport has become 70 per cent more fuel-efficient and accounts for about two per cent of global emissions of fossil carbon dioxide. But since air travel is growing, the industry needs to work hard to further reduce emissions.
Environment  carbon dioxide

In Sweden, air transport accounts for four to five per cent of total carbon dioxide emissions. The transport sector as a whole is responsible for about one third of Swedish carbon dioxide emissions.

Did you know that:

Speeding on Swedish roads produces more fossil carbon dioxide emissions than domestic air transport
Air transport has become 70 per cent more fuel-efficient over the past 40 years

Global environmental targets for air transport

Because air transport is part of a global industry, its environmental impact is handled in a global context. Air transport is the first worldwide industry to agree to long-term global environmental targets:

  • Air transport emissions of fossil carbon dioxide shall be reduced 1.5 per cent per passenger and kilometre to 2020. After this, growth in air travel shall be climate-neutral.
  • Actual emissions of fossil carbon dioxide in 2050 shall be half the level in 2005.

In October 2016, countries around the world signed a global climate agreement, the Carbon Offsetting and Reduction Scheme for International Aviation, or CORSIA. Negotiations have been under way for many years, and for the first time in history an entire sector reached an agreement on a global instrument to handle its environmental impact.  As a result of this roadmap, emissions for air transport will not exceed the level in 2020 and will be half the number in absolute terms by 2050. This target is in line with the emissions allowable to achieve the UN’s emissions target for 2050.

The air travel industry faces a major challenge: meeting continued strong passenger growth while continuing to reduce its greenhouse gas emissions.

Many efforts are being made to reduce the environmental impact of air transport, in particular by improving the environmental performance of aircraft. European aviation research and the air transport industry expect that by 2020 aircraft will be developed with 50 per cent lower fuel consumption and carbon dioxide emissions, 80 per cent lower nitrogen oxide emissions and half the noise levels compared to aircraft manufactured today.

Compared to aircraft from the 1960s, today’s aircraft are 70 per cent more fuel-efficient per person-kilometre. The most modern aircraft use about 0.03 litres of fuel per passenger-kilometre.

Rapid advances in alternative fuel for commercial air traffic are also being made. Bioaviation fuel can be made from different renewable materials, such as forest and food waste.  

In the Nordic countries, biofuel is made from used cooking oil, which reduces carbon dioxide emissions by at least 80 per cent compared to the same amount of fossil aviation fuel.

One biofuel with great potential is algae fuel, which yields a relatively large quantity of fuel compared to other plants. Because algae are water plants, they do not compete for farmland and can grow relatively quickly under the right conditions.

In Sweden, by-products from the forestry industry are the material currently of greatest interest. Biofuel can be mixed with today’s fossil fuel and will constitute a significant share of this mixture as early as 2020.

You can read more about the air transport industry’s international climate work here. 

Together with Nordic airlines, airports, government authorities and aircraft manufacturers, Swedavia is pushing for an increased supply of biofuel to the industry. The work is being carried out in part under the framework for the Nordic Initiative for Sustainable Aviation (NISA). Swedavia is also a partner in the economic association the Fly Green Fund, whose aim is to increase demand and access to biofuel in the Nordic countries.

Another factor contributing to lower fuel consumption and emissions is green flights, a three-part concept that consists of green departures, straight flightpaths and green approaches. This is being developed in a partnership between Swedavia, air traffic management (the Swedish Civil Aviation Administration) and the airlines. 

Did you know that: The most modern aircraft use about 0.03 litres of fuel per passenger and kilometre.

Green flights

The concept of green flights consists of green departures, straight flight paths and green approaches.
Green flight

A green approach entails the aircraft continuously descending from its cruising altitude down to the landing runway. Because the descent is continuous, hardly any jet thrust is needed, which saves fuel and reduces emissions.

Since the aircraft’s computer has continuous contact with equipment on the ground, the entire flight is adjusted based on the exact landing time. Together the air traffic controller and pilot can plan an even approach – the plane glides down instead of step-by-step, as is the case today. An approach like this can save up to 150 kg of fuel and 450 kg of carbon dioxide emissions. Noise is also reduced since the aircraft does not need to use engine thrust at lower altitudes.

Green approaches have been developed at Stockholm Arlanda Airport in a partnership between Swedavia, international air traffic control bodies and SAS. So far, it has only been possible to carry out green approaches during light traffic since green and normal approaches cannot be used together during heavy traffic.

Shorter flights

Green Connection is a project aimed at optimising and shortening the entire flight. In this project, trials have been carried out in which the flight path between Stockholm Arlanda and Göteborg Landvetter Airport was shortened using modern satellite-based technology.

Questions and answers about biofuel

Why is it important to invest in bio aviation fuel?

“The world needs to reduce its dependence on fossil fuels, and the entire transport sector needs to switch over to renewable fuels.

“Air travel, whose main environmental impact is from the emission of fossil carbon dioxide, has made enormous progress in reducing carbon dioxide emissions per passenger over the past 30-40 years. The industry’s target is to cut emissions of fossil carbon dioxide by half in absolute figures by 2050 compared to 2005. Biofuel is a key factor in this. The technology already exists. What is missing is large-scale production of fossil-free aviation fuel at a competitive price.”

Is there enough bio material to supply the air travel industry with renewable fuel?

“A Norwegian study shows that there is enough material in forests to meet the needs of air travel. If road transport were required to run on electricity or hydrogen gas to a greater extent, biomass could then be freed up for air travel.

“The possibility of producing bio aviation fuel from algae, which can be cultivated in the sea, offers good potential in the future to supply the air travel industry with renewable fuel. Given the great productivity of algae, it could replace oil without using unreasonably large areas for cultivation.”

Does using bio aviation fuel affect what are called high altitude effects?

“The introduction of bio aviation fuel means that we reduce emissions of fossil carbon dioxide and thus our impact on the climate. High altitude effects can be managed firstly through technical and aviation operations measures. It is mainly nitrogen oxide and water steam that have an effect on the climate at a high altitude. It is still uncertain what this effect looks like, but research is under way to enable us to better understand this mechanism.

“Due to the different ways different emissions affect the climate as well as due to the different lengths of time they remain in the atmosphere, emissions must be treated on an individual basis. This will enable identification of the best ways to reduce the total impact of flying on the climate.”

Why does Swedavia choose to buy green flights for official business?

“For many reasons. First, we reduce our own impact on the climate. But by leading the way and buying green flights for official business, we also want to show others, especially decision-makers and producers, that there is a demand for renewable fuels in the air travel industry too and in that way help large-scale production get under way. At the same time, we show other companies that it is already possible today to choose renewable aviation fuels. With the right measures, we can have fossil-free domestic air travel in Sweden by as early as 2030.”

How would that happen?

“Today we know how much fossil carbon dioxide emissions Swedavia accounts for in its flights for official business. Since 2016, we pay a premium on each flight our employees take for business purposes so that the airlines will use fossil-free fuel instead of regular aviation fuel.

“Swedavia does not own its own fuel. Instead we have purchased a service from a fuel broker, who supplies it. It works the way it does with green electricity. You pay for the amount of renewable aviation fuel you use, but it is not entirely certain that your own flight will be fuelled with renewable aviation fuel. The fuel comes into the system, so to speak, and that is what is important.”  

What does the possibility of buying bio aviation fuel look like today?

“The market for biofuel is still not mature. At present there is no continuous, large-scale production of bio aviation fuel in the world. The fuel produced so far has been made to order and on a small scale. In other words, the supply is limited. That makes our efforts even more important.

“We hope that more organisations and individuals will follow our lead and require biofuel to be used when they fly in order to send a clear signal to producers that there is a demand and thus incentive to invest in local, large-scale production in the Nordic countries.”

Can today’s aircraft fly on biofuel?

“Yes, the product is the same whether it comes from fossil or renewable materials. The air travel industry has agreed on a number of specifications that aviation fuel, JetA1, must fulfil – the same goes for renewable fuel. Today a mixture with 50 per cent biofuel is allowed but going forward that percentage can hopefully be higher, perhaps even 100 per cent.” 

What is biofuel made of?

“In the flights carried out in the Nordic countries so far, waste cooking oil is used as material for the fuel. In Sweden, by-products from the forest industry are the most interesting alternative at present.  These fuels can be mixed with today’s fossil fuels, and it is expected that they will constitute a significant percentage of the mixture by 2020.

“Another biofuel with great potential is algae oil, which produces a relatively large quantity of fuel compared to other plants. Since algae are water plants, they do not compete for land for cultivation and can grow really quickly under the right conditions.  There are stringent sustainability requirements for the fuel that is to be used, and it is important that bio aviation fuels are produced from materials that do not compete with food production or are harmful to the environment.”

What is the price differential between fossil fuel and bio aviation fuel?

“Today renewable fuel is several times more expensive than fossil fuel. The price has fallen from seven-eight times higher than fossil fuel before to three-four times higher since 2009. In the past year, falling crude oil prices have caused the price differential to increase again. However, since the market for bio aviation fuel is not mature, it is difficult to give a price for the product.”

Why is it so difficult to get production going?

"There has not been demand for it and there are still not enough incentives for increased use. Add to that the low price of crude oil. But with the large-scale production of bio aviation fuel, the price will be pushed down."

Meet Lena Wennberg Environmental manager at Swedavia

Air transport is often portrayed as a climate villain. How large an environmental impact does it really have?

“In Sweden, air travel accounts for four to five per cent of total carbon dioxide emissions. In comparison, the transport sector accounts for one third of all carbon dioxide emissions, and manufacturing emits roughly the same amount. We certainly do not want to disregard the emissions from flying, but it is important to set this in relation to other emission sources as well as to the benefits to society.  

“We live in a globalised world, where trade and tourism are important to the global economy. We humans need to meet, which is why I do not think air travel will decrease. However, the air travel industry bears great responsibility, and intensive work is under way at the global level to reduce the climate impact of air travel. One of the targets we are working towards is to reduce carbon dioxide emissions by 1.5 per cent per passenger-kilometre each year to 2020. After that, the growth in air travel shall be climate-neutral, and by 2050 emissions of fossil carbon dioxide from air travel shall have fallen 50 per cent compared to the level in 2005.”

What is the top environmental issue on Swedavia’s agenda?

"The climate issue, which is not just important for us but for all society. Our objective is to not emit any carbon dioxide from our own operations by 2020. Another objective is that we shall have fossil-free domestic air travel by 2030. Today at Swedavia, all flights for official business use renewable aviation fuel. With this move, we want to increase demand for renewable aviation fuel but also inspire other companies and organisations to follow our lead. Together we can create more sustainable air travel."

What are you most proud of Swedavia having achieved?

“Obviously, we haven’t achieved our target of zero carbon dioxide emissions from our own operations yet. There are still about 2,000 tonnes and a few years left, but there is incredibly strong engagement among employees at our airports to achieve our zero vision. Ronneby Airport has already reached its target, and the airports in Östersund and Luleå will achieve their carbon dioxide goal in 2019. Part of our climate work involves us buying only green electricity, and the airports in Malmö and Gothenburg have their own solar energy facilities.

“We’ve also assessed the vehicles used at the airports and switched to cars that run on electricity. For larger vehicles such as snow removal equipment, they now run on biogas or biodiesel (HVO). However, we still have a few nuts to crack. For the uninterruptible power supply, we have not yet found any bio oil that can be stored for long periods, and we need to also find a fossil-free alternative to the fossil fuel used for firefighting exercises at some of our airports.”

How far have you come compared to airports in other countries?

"We are the only large airport group in the world to achieve the highest level of environmental certification, Airport Carbon Accreditation (ACA), for all of our airports. That means we measure, reduce and set targets to reduce greenhouse gases. We also influence other operations in the airport area so that they also measure and reduce emissions. We carbon-offset the emissions we have not managed to reduce. As far as I know, we're the only airport group in the world that has an explicit zero vision for carbon dioxide emissions, and our airports are among the few that offer biofuel to airlines.”

What suggestions do you have for passengers who want to fly climate-smart?

"If you want to reduce your carbon footprint, you should choose the route and the airline with the lowest carbon dioxide emissions. On some air travel websites, you not only can compare prices but also see what emissions the flight produces. You can also choose to fly using biofuel, a service offered by the Fly Green Fund. It costs about SEK 300 extra to fly fossil-free for one hour, and it is easy to pay using the Swish app. As for the journey to and from the airport, you can also think about what's best for the climate."

Do you encounter any prejudices about the environmental impact of air transport?

"Yes, some people think, for instance, that aircraft dump fuel before landing. But that's not the case. This may happen in an emergency, and then only on intercontinental flights. In the Stockholm region, it happens perhaps two or three times a year that an aircraft needs to get rid of fuel, but then that happens at such a high altitude that the fuel is converted into steam."

About Lena Wennberg

Job: Environmental manager at Swedavia

Employed at Swedavia since... I started in 1998 in the Stockholm Division as environmental manager (Arlanda and Bromma) when LFV operated the airport.

My environmental interest was sparked ... when I was little, I was in Skogsmulle (an association that promotes outdoor activities for young people), I was a scout and I’ve always loved animals.

Best suggestions for a more sustainable everyday life: use green energy in your home, eat more vegetables, eat local/organic, sort your waste and take mass transit. Air travel is a mode of mass transport, and people can choose to fly on biofuel.

Lena Wennberg

Other emissions from air transport

Aircraft engines emit carbon dioxide, nitrogen oxides, hydrocarbons, soot, particulate matter, carbon monoxide and sulphur dioxide.
Other emissions

Sometimes people can smell aviation kerosene at airports. Sulphur compounds in the aviation kerosene, so-called mercaptans, have a penetrating, intensive and characteristic smell in very small concentrations. However, mercaptans are not toxic in the low concentrations found at Swedavia's airports.

World leader in operating climate-smart airports


All of Swedavia’s airports are certified at the highest level of Airport Council International Europe’s standard for the climate work of airports. Stockholm Arlanda Airport was the first airport in the world to receive the highest certification. Certification means that all of Swedavia’s airports continuously reduce fossil carbon dioxide emissions from their operations, that they help other operations at the airports to reduce their emissions and that Swedavia offsets the emissions it has not yet reduced. As a result of its certification and work to switch to renewable aviation fuel, based on this standard Swedavia is the airport group that has come furthest in the world in its work to develop climate-smart airports.

You can read more about the ACA certification programme here.

Different levels:

Mapping, Reduction, Optimisation and Neutrality. There are four levels in ACA climate certification at which the work of the airports is assessed and graded. Certification at the highest level, 3+, requires the airport to be entirely climate-neutral in terms of emissions from its own operations. When an airport has complied with the requirements for the highest level, it means that all other steps on the scale have also been complied with.  

Level 1 (Mapping): Means that the airport shall determine the emission sources it has control over, Scope 1 or 2, under the Greenhouse Gas Protocol. The airport shall calculate carbon dioxide emissions in accordance with ISO14064 standards and compile a carbon footprint report. The report shall be verified by an independent auditor.


Level 2 (Reduction): All of the above plus the airport shall provide evidence that it has effective carbon dioxide procedures and that a reduction was made in carbon dioxide emissions. Efficient carbon dioxide procedures include showing that the airport has a low carbon policy, allocating responsibility, monitoring fuel and energy consumption, communicating with relevant stakeholders, setting carbon/energy reduction targets and training staff.


Level 3 (Optimisation): All of the above plus the airport involves other companies and organisations at the airport in reducing their carbon dioxide emissions. This third-party engagement includes airlines and different service providers such as ground handling companies, catering companies, mass transit companies and others that work at the airport. This level widens the scope of the airport’s carbon footprint to include, at a minimum, emissions from aircraft taking off and landing, surface transport to the airport for passengers and staff, and employee travel on official business.

Level 3+ (Neutrality): All of the above plus the airport offsets the remaining emissions it has control over (Scope 1 and 2) that it has not reduced on its own. Offset is done by investing in projects in developing countries through which a corresponding amount of carbon dioxide is absorbed.

More information about the programme

The organisations behind the Airport Carbon Accreditation programme are Airport Council International Europe (ACI Europe), ACI Asia-Pacific, ACI Africa and the consultancy firm WSP Environment & Energy. The programme complies with the Greenhouse Gas Protocol, the international standard develop by World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD).

“We will not only be a good role model. We will also be involved in driving development in a sustainable direction.” Jonas Abrahamsson, CEO.

“We will not only be a good role model. We will also be involved in driving development in a sustainable direction.” Jonas Abrahamsson, CEO.