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Climate Change, A Global Concern for all Aviation Stakeholders

Climate Change, A Global Concern for all Aviation Stakeholders

Climate Change, A Global Concern for all Aviation Stakeholders

“Aviation’s CO₂ emissions are projected to keep growing in the long term. There is an urgent need for all stakeholders to take action”. 

In the past decade, the impact of climate change on our world has become a subject of global concern. The global aviation industry produces around 2% of all human-induced carbon dioxide (CO₂) emissions, representing around 11% of CO₂ emissions from transport worldwide. In 2015, ICAO had forecast an annual growth rate for air traffic of around 4.6% until 2025, but the COVID-19 crisis had other plans. Despite this severe reversal of air traffic growth being experienced at the moment, a return to previously projected growth is expected in the medium term.

Though airports are seen as being the main stakeholders in this aspect, they also play an important role is driving collaboration between all operational stakeholders, in reducing the sector’s carbon footprint.

Unfortunately there is currently no airport in any country that is required by law to achieve carbon neutrality. On the positive side, certain airport operators in different parts of the world have been gradually channeling their efforts to reduce their CO₂ emissions, through an independent programme called Airport Carbon Accreditation (ACA). While other airports have chosen to directly offset their emissions through their Corporate Social Responsibility or Sustainability programmes.

With all the different strategies to mitigate these emissions, some airports would ask, if they wish to progress to becoming carbon neutral, what is the most effective way to identify and manage carbon emissions? The answer would be to participate in a globally recognised carbon management programme for airports that independently assesses and recognises airports’ efforts to manage and reduce their CO₂ emissions such as the already mentioned ACA program. Through this program Greenhouse Gas (GHG) emissions are managed and identified by three different scopes, namely Scope 1, 2 and 3, as categorised by World Resources Institute (WRI).

It is important for airports to be aware of the 3 different scopes of emissions present within its boundaries because this will assist in the recognition of emission sources (identify ownership), control of emissions sources and thus responsibility for managing the emissions. Each of these scopes of emissions should be reported by an airport; first the total emissions of scopes 1 & 2 and then separately the scope 3 since they are two different types of emission factor, market and location based as this helps to avoid double counting of the same emissions.

Envisa has long experience in supporting airports in achieving the ACA certification and other carbon management programs all around the world. This is complemented by its extensive delivery of robust environmental impact assessments and participation in European R&D programmes in the aviation sector. 


Importance of Identifying the 3 Scopes

If we take a scenario of electricity consumed at the airport, it may come from many different power production sources such as, non-renewable generation from offsite, on-site renewable power generation and there are also cases of the airport re-selling this power to the tenants and many other scenarios. Such cases are what lead to categorizing GHG emissions into the 3 different scopes to avoid double counting of the same emissions. Hence, in managing carbon emissions, it is of great importance that an airport identifies that sources of emissions and the different emission boundaries within the airport.

In consistence with the emission identification by scope, the reporting of emissions should be done separately for each scope, as laid out in the Airport Carbon and Emissions Reporting Tool (ACERT) tool, recommended by Airports Council International (ACI), to calculate these three scopes of emissions. Sometimes an airport can calculate one or two scopes at the same time while following ACI accreditation guidelines. While other airports prefer to calculate an individual scope’s carbon footprint before accreditation, for example scope 3 emissions can be calculated in a separate project in preparation for ACA level 3 accreditation.

For constant control and management of emissions, it is best for airports to maintain the good practice of carbon management by beginning to participate in the ACA program for airports with no accreditation and for those accredited they can annually either upgrade their ACA level or renew their current ACA level.

Managing the 3 Different Scopes of Emissions

An airport has more influence on what is under its control, hence Scope 1 emissions are owned or controlled by the airport operator and can be managed easily by the airport. Once the footprint of these emissions is calculated, the airport controls the emissions by reducing or offsetting them. With respect to the emission source, the reduction measures for Scope 1 emissions can be, implementation of new on-site waste and wastewater management technologies, introduction of electric ground support equipment to replace fossil fuel vehicles, and many more. Reducing some emissions can be a challenge since not all sources of emissions have more efficient technology innovations present to date that can be used to replace the existing.

Scope 2 emissions defined as GHG emissions from the off-site generation of electricity (and heating or cooling) purchased by the airport operator, can be managed by the airport with some limitations. Reduction measures can be implemented and currently the most common is the implementation of solar power generation systems, to reduce the amount of power that the airport purchases from non- renewable off-site power generation source. Airports having renewable heating source such as geothermal, do not need any energy reduction measures as this source is considered emission free. Like for scope 1 emissions, some emission sources do not have enough efficient replacement options.

It is more challenging to manage Scope 3 emissions since they are emissions from airport-related activities from sources which are not owned or controlled by the airport operator. This shows that managing GHG emissions in an airport is not just about the airport, but there are other GHG emitting activities within the airport boundaries that are involved such as airport tenant, third parties and other stakeholders. Hence, to help reduce these emissions, third-party engagement methods have proven to be the most effective. These engagements with third parties serve to urge them to become more efficient, less polluting, and smarter in their choices.

For all the 3 scopes of emissions, after reducing all emissions via various methods, the remaining carbon footprint equivalent can by invested in responsible carbon offsetting projects. It is recommended to offset after knowing the carbon footprint of all 3 scopes within the airport, then after the airport can be considered carbon neutral. The ACI ACA has now two ACA levels, namely level 3+ (Neutrality) and Level 4+ (Transition) to guide airports offset their emissions by investing in globally recommended offsetting projects.

In most cases for an airport, when Scope 1 and 2 emissions are combined, they make a smaller proportion of emissions than scope 3 emissions alone. This is the reason why airports are encouraged to strive to reach ACA level 3 accreditation in order to have a full view of all the scopes present within their boundaries.

Benefits of Managing all 3 Scopes of Emissions

Among the benefits of managing carbon by scope, the data collection phase brings an engagement between the airport itself and the third parties.

Economically, airports can save their financial resources by purchasing off-site non-renewable generated power to on-site solar power generation. Or if the airport switches to more efficient energy sources such as electric cars, it will save the funds spent on offsetting their fossil fuels consumed by fossil fuel vehicles and many more examples.

Environmentally and socially, the amount of carbon emissions that an airport generates from all 3 scopes of emissions affects the quality of air – which is a danger to human health,  a major cause of climate change non – conducive environments for animals and plants. Hence carbon reduction and offsetting practices by an airport are of great benefit to our environment.

Other Carbon Management Related Projects

During the years of experience in Carbon Management projects, Envisa has been conducting detailed emission assessments in different airports and helped the airports in their carbon neutral process. Envisa can recommend the following services related to managing the 3 scopes of emissions in an airport:

  • Participation in ACA programs – voluntary approach which allows airports to obtain a label according to their level of accreditation, but above all, gives them recognition from their peers and the public.
  • GHG foot printing and identification of opportunities for reduction.
  • Local air quality modelling and impact mitigation – as the 3 scopes of emissions affect the quality of air at an airport.
  • Waste management – falling under scope 1 emissions this can be considered as an independent project.
  • Energy management and optimisation – a high percentage of all the 3 scopes emission comes from energy consumption or production sources, hence conducting an Energy management and optimisation project would be of great value to the airport.

Envisa experts will be delighted to provide any of these services for you and to make it in the most relevant way according to your platform. In addition to the mentioned services, we  help you collecting the required data, writing the mandatory documents, and facilitating meetings with your stakeholders by workshops.

Do not forget to learn more about our solutions to tackle environmental issues in the aviation sector, and you can also read about our previous work at airports.

Please, do not hesitate to contact us for any questions or remarks by email: towani.mtonga@env-isa.com, and follow our activities on our website and LinkedIn page.


About the author



Energy & Environment Engineer


Towani MTONGA is an Energy and Environment Engineer who holds a ME3, Masters of Sciences in Management and Engineering of Environment and Energy from the IMT Atlantique Nantes in France. She is a Junior Consultant at ENVISA, and her principal responsibilities include assisting with Airport Carbon Accreditation (ACA) Projects and performing airport noise assessments. 


The new era of airport hubs?

The new era of airport hubs?

The new era of airport hubs?

As a consequence of the travel restrictions imposed on fights due to the global COVID-19 pandemic, airlines have reduced their capacity offers and grounded part of their fleet, particularly the big quads such as B747 and A380. These aircraft being mainly operated to connect hub congested airports, the hub-and-spoke system seems to be over, to the benefit of more point-to-point flights. So how can one envisage a new era for airport hubs?


The fate of traditional hubs

In a broad organizational context, a hub is the effective centre of an activity, region, or network. For aviation, hub airports are traditionally meant to concentrate passenger traffic and flight operations at a given airport and mainly serve as transfer (or stop-over) points to get passengers to their destination. It is part of the famous hub-and-spoke system by which an airline will operate flights from several non-hub (spoke) cities to the hub airport, and passengers traveling between spoke cities need to connect through the hub, thus creating economies of scale. It allows an airline to serve city-pairs that could otherwise not be economically served on a non-stop basis (point-to-point model).

Long-haul flights, performed by big aircraft models such as B747 and A380, connect these hubs and airlines operate fewer flights to serve a higher number of destinations and operate fewer aircraft.

However, when they can choose, passengers prefer to avoid congested hub airports where they must queue for another flight to their destination and prefer to have a direct point-to-point flight. Moreover, even if the hub-to-hub flight can be a kind of aircraft-sharing (by analogy to car sharing), connecting through a hub airport can actually mean flying a longer distance for each passenger, then having a bigger (climate change) environmental impact. As engine performance and reliability has dramatically improved over time, twin-engine aircraft are now allowed to fly more direct routes even above seas, oceans or desertic areas, making them far more competitive and more fuel efficient than quads.

The impact of COVID-19 and associated restrictions

For about one year now, the various lockdowns and travel restrictions in reaction to the COVID-19 pandemic have affected air travel like no other economic sector. In 2020, demand for air travel (revenue passenger kilometers or RPKs) fell by 65.9% compared to the full year 2019[1], by far the sharpest traffic decline in aviation history. Europe’s airports lost 1.72 billion passengers in 2020 compared to the previous year, a decrease of -70.4%, bringing them back to their traffic level of 1995[2]. To adapt their capacity to the current demand, most companies have parked a large part of their fleets, temporarily or permanently. The current economic stress, doubled with environmental pressure for operating aircraft that are more fuel-efficient and consequently emit less CO2, generated the end of operations of quad-engine aircraft (B747, A380 and A340). These aircraft will probably be scrapped and dismantled, and hopefully recycled by some experts of aircraft green recycling such as TARMAC AEROSAVE.

In such conditions, who could pretend that we are entering a new era for airport hubs?

New sources of energy

CO2 emissions from civil aviation represent about 2% of man-made CO2 emissions[3], and are directly proportional to fuel burn by a factor of around 3.16. In other words, each ton of fuel burnt emits 3,16 tons of CO2; this relation is pure chemistry and has nothing to do with technology or operations. Although the share of aviation’s CO2 emissions remained globally constant over the past decades[4], the absolute emissions keep increasing as traffic increases, reaching 915 Million Tons in 2019 [3].

Assuming that the traffic will recover from the current crisis associated to the COVID-19 consequences, one of the key solutions to decarbonize the sector is to speed and scale up the development and usage of new types of energy, including electricity, hydrogen and sustainable aviation fuels (SAF).

To achieve the industry’s ambitious goal of reducing the CO2 emissions of the sector by half in 2050, compared to 2005 levels and to be consistent with the global requirements of the Paris agreement, all new types of decarbonated energy need to be considered. However, SAF will have a predominant role in that process as they are already available (even if the level of available volumes needs to be scaled up) and will remain the only solution for medium and long-haul flights in the period running to 2050[5].

About the author

Philippe Fonta

Philippe Fonta


After 20 years in the aviation sector (manufacturer, international coordination) and 8 years in a worldwide non-for-profit organization on Sustainable Development, Philippe Fonta is now advising companies and organizations on Sustainability, Corporate Responsibility, and Uncertainties Management through his SCRUM-Consult consultancy firm.

Do not hesitate to contact him by email: P.fonta@scrum-consult.com 


There are obviously different sources of SAF, from municipal solid waste to agricultural waste residues, waste oils and some form of biomass (no competing with food chain). The Emission Reduction Factor (ERF) of these SAF seem to be between 70% and 80%, so they are quite promising.

But there is another solution which looks even more promising: the development off so-called e-fuels or Power-to-liquid (PTL) fuels. Using renewable electricity to convert CO2 (captured from industrial processes or directly from the air) into SAF. They could be deployed anywhere in the world, initially near existing industrial facilities as the capture of CO2 from industrial facilities is more efficient than from Direct Air Capture (DAC) from the atmosphere where CO2 is much more diluted. Combining this potentially unlimited source of supply with green hydrogen would make the process more efficient.

Some heavy industrial sectors, such as cement or steel manufacturing are considered as “hard-to-abate” sectors[6], together with international maritime and aviation sectors, because they will have difficulties to de-carbonate their activities. For instance, in 2018, the cement sector developed a low-carbon technology roadmap in partnership with the International Energy Agency (IEA): this roadmap identified that in order to match the 2°C scenario of the IEA (2DS[7]), about half of the emissions of CO2 from the sector will need emerging and innovative technologies, carbon capture[8] being one of them. The cement sector has been active over the past decade on studying and developing pilot projects on carbon capture utilization and storage (CCUS). Recently, LafargeHolcim, a major worldwide cement manufacturer, partnered with OMV, VERBUND and BOREALIS for the joint planning and construction of a full-scale plant by 2030 to capture CO2 and process it into synthetic fuels, plastics, or other chemicals.

The project, named ‘Carbon2ProductAustria’ (C2PAT), aims at converting the 700,000 tons of CO2 per year into synthetic fuel by OMV.

This example shows that no-one will solve the challenge of climate change and CO2 emissions alone, and that gathering multiple stakeholders on a single hub location would enhance synergies of success.


Future Power-to-Liquid hubs?

Is this opportunity of grouping activities into hubs and produce synthetic fuels for aviation happening? Up until recently, I would have argued that the sector has identified the technical opportunity but did not engage in such partnership initiatives. However, beginning of February 2021, three main announcements indicated a possible change in the mindset:

On February 8th , 2021, during the High-Level Conference on Synthetic SAF organized in the Netherlands, two main initiatives were launched:

  • Synkero, a start-up company that will focus on the development of a commercial synthetic kerosene facility in Amsterdam, using captured CO2[9] and hydrogen, and
  • Zenid, which aims to build the world’s first industrial size demonstration plant (in Rotterdam area) for sustainable aviation fuels made from air. Direct air capture technology provides CO2 to a highly efficient co-electrolysis unit, that turns the CO2 and added water into syngas. The syngas is transformed into liquid hydrocarbons by a modular Fischer-Tropsch Reactor and then refined into sustainable aviation fuel.

On February 11th, 2021, whereas most of the French media attraction was directed towards the decision of the French government to cancel the extension of CDG airport, a more positive initiative was launched by Groupe Aéroports de Paris (ADP), the Île-de-France Region (Paris area), the Choose Paris Region agency, the Air France-KLM group and Airbus: “an unprecedented call for expressions of interest to explore the opportunities offered by the hydrogen at Paris airports and meet the challenge of decarbonizing air transport activities”. The objective is to create a real “hydrogen hub” at Paris airports by building an ecosystem federated around hydrogen, with major corporations, laboratories, start-ups and universities.

It is worth noting that in January 2021, representatives from the European aviation sector and environmental groups, together with a research organization and a sustainable aviation fuel supplier, have come together to provide recommendations to EU policymakers on sustainability aspects and support for future aviation fuels. Among the recommendations put forward in a consensus statement published by the initiative are to:

  • prioritize e-fuels and fuels made from wastes and residues;
  • exclude biofuels produced from dedicated cropland;
  • execute case-by-case assessments of local environmental impacts; and
  • support multiple technology pathways.


Aviation will definitely need new sources of energy and fuel to fully decarbonize its activities. New types of energy for aviation (electricity and hydrogen) offer real potential for short-haul aircraft in the coming years. However, in the meantime and to fuel longer-haul flights, responsible for about 80% of the global CO2 emissions from aviation, Sustainable Aviation Fuels (SAF) will play a key role and their potential needs to be scaled-up and supported by governments and the financial community.

All types of SAF need to be considered if they meet the quality and sustainability criteria defined by ICAO and the certification bodies. As airports represent the places where aircraft are refueling, as they are frequently located close to industrial activity where CO2 could be captured at industrial sources in more concentrated forms than through direct air capture (DAC), they are an ideal place to develop Power-to-Liquid (PTL) fuels. Combined with green hydrogen, that could also be produced within airport boundaries, airports should enter into a new hub era, concentrating some fuel production activities within their perimeter, thus reducing the need to transport this fuel and the volume of storage, being used by aircraft and other airport vehicles (hydrogen buses and trucks for instance).

Partnerships needs to be established and cooperation between different sectors of the “had-to-abate” sectors through which the carbon produced by heavy industries could become the source of fuels for others, creating a New International Carbon Economy (NICE).


[1] Source : IATA – https://www.iata.org/en/pressroom/pr/2021-02-03-02/

[2] Source : ACI Europe – https://www.aci-europe.org/media-room/303-europe-s-airport-2020-passenger-traffic-back-to-1995-levels.html

[3] Source : ATAG – https://www.atag.org/facts-figures.html

[4] The IPCC Special report “Aviation and the Global Atmosphere” in 1999 estimated that aviation emissions were around 2% of global anthropogenic emissions (1992 data): Page 6 of the Summary for Policy Makers (SPM)

[5] ATAG Waypoint2050 report

[6] Source : Energy Transition Commission « Mission Possible » : https://www.energy-transitions.org/publications/mission-possible/

[7] 2DS is an IEA scenario with at least a 50% chance of limiting the average global temperature increase to 2°C by 2100.

[8] “The integration of emerging and innovative technologies like carbon capture and reducing of the clinker content in cement are identified to provide the largest cumulative CO2 emissions reductions in the 2DS compared to the RTS by 2050, with 48% and 37% contributions, respectively.” Page 5 of the Technology Roadmap – Low-Carbon Transition in the Cement Industry (iea.org)

[9] Multiple sources possible : point source capture (industry), bio-based or Direct Air Capture (DAC)

To meet the environment challenges of the 21st century…this is the duty of airports!

To meet the environment challenges of the 21st century…this is the duty of airports!

To meet the environment challenges of the 21st century…this is the duty of airports!

“Envisa is ready to help your airport get started on the sustainability pathway” 

In a society where environmental issues have become a major concern, the aeronautical sector has to evolve in order to ensure a sustainable future, both for its industry and for the planet. As part of the ecosystem and as the first gateway between the population and the world of aviation, airports have a duty to set an example and take concrete steps to meet the challenges of the 21st century.

In order to help catalyse the airports’ approach, the Airport Council International (ACI) decided to create a voluntary program in 2009, the Airport Carbon Accreditation (ACA), which is now open to airports from all around the world.

As aviation and environmental experts, Envisa consultants have been helping airports for many years to get into the program.  

What is the Airport Carbon Accreditation program?

The ACA program was created to enable airports to understand their sources of emissions, to control them and to take actions to reduce the induced pollution. Its aim is also to make the accredited airport gain recognition from the society and its peers for its commitment to tackle environmental issues, and to encourage others to follow its lead.

The ACA program has been also set up to enable authorities and decision makers to understand the impact of the airports around the world, in terms of activity, movements and emissions.

Based on 4 different levels of accreditation, it allows airports to evolve progressively and at an individual pace, from the identification of the sources of emissions to their reduction.

Once a level is achieved, the airport has to renew its accreditation every year or to evolve to the next one, so that the program ensures the continuous efforts from the airports.

Some figures about the Airport Carbon Accreditation

Worldwide, more than 300 airports are accredited, all levels combined, which represent about 45% of the global air passenger traffic.

The ACI estimates that on the period July 2018 – June 2019, 322,297 tonnes of CO2 were avoided thanks to the program, with the reduction actions taken by the airports.

More than 700,000 tonnes of CO2e were also offset by the airports, following recognised offsetting programs.

What the ACA program is actually measuring?

The Airport Carbon Accreditation Program focuses both on measured data but also efforts made by the airports to ensure the emissions are managed and reduced.

The program first requires actual consumption data from different sources, in order to measure the related emission. It is important for an airport to compute its emissions to understand where they are in terms of pollution, and on what department they have to act.

In addition, further in the program, the airport will also have to prove its management in order to achieve reduction targets, the involvement of the third parties present on site, and the actions taken to reduce emissions where the airport does not have direct control.

4 levels of accreditation

The programme is structured into 4 levels. Each year, the airport can decide to upgrade to the next level, or renew its accreditation for the same level.

It is also possible for an airport to join the programme at any level, as long as it meets the requirements of the previous ones.

In order to understand the different levels of the ACA program, just click here to get the requirements of each of them!

Added value for the airports

Joining the ACA program enables the airports to set up a strategy to manage its carbon emissions and to ensure its continuous improvements.

As part of the Airport Carbon Accreditation program, the airport will strengthen and benefit from the exchange of best practices between the platforms.

The recognition gained by the airport from the society will allow it to encourage a dynamic reduction in emissions beyond the airport perimeter, and to highlight the action taken by airports with regard to environmental issues.

The ACA program & COVID-19

Why would an airport bother to start an environmental procedure such as the ACA program, when the industry is severely impacted by the COVID-19 pandemic?

As aircraft movements and airlines services have been significantly reduced this year,  the emissions of an airport do not represent what would have been called “emission of a normal year”, so ACI has decided not to take into account the data for the entire year 2020.

This decision leads to two beneficial consequences for airports. Those who already joined the program will not have to renew their accreditation next year. As for those who consider joining the program in the coming months, their accreditation will hold for two years instead of one.

Envisa highly recommends airports to join the program before May 2021, in order to benefit from this decision.

How to join ACA program?

As an airport, once you decide to join the program, you will need guidance to make a good start. This is why we recommend you get in touch with professionals such as Envisa’s team.

At Envisa we will guide you on how to get into the program, and how to complete every requirement of it. With our experience, we are able to help you to collect the required data, to write the mandatory documents and much more, like facilitating meetings with your stakeholders.

Do not forget to learn more about our solutions to tackle environmental issues in the aviation sector, and to read about our previous work at airports.

Stay tuned for a new case study dedicated to the ACA program in the coming days.

Please, do not hesitate to contact me for any questions or remarks, and follow our activities on our LinkedIn page.


About the author



Environmental Engineer

Martin FORESTIER is an environmental engineer who graduated from Grenoble INP – Ense3.  He joined Envisa after working at the Environmental Research Institute in Thurso, Scotland. Passionate about aviation but also convinced by the environmental issues that the aeronautical sector is facing, he is the Airport Carbon Accreditation project leader at Envisa. Martin is giving training on the topic and presenting subsidy programs to airports and associate companies.  Besides, Martin is managing the emissions calculations of different GHG scopes delivered to airports. He has also experience with aircraft end-of-life cycle studies.

You can contact him on his email address: