Why is it important?
In a globalised world where travel has become a routine part of daily life and air travel is now viewed as an ordinary activity, aviation has become one of the fastest-growing sources of greenhouse gas emissions, currently contributing to 2.4% of global CO2e emissions(1). By 2050, this share could increase to 22%(2). At a sectorial level, professional travel represents, for example, 7% of the total carbon footprint of the international aid sector.(3)
Beyond CO2 emitted from burning fuels, air raft engines also affect the concentration of other atmospheric gases and pollutants. When released at high altitudes, these emissions alter the physical and chemical properties of the atmosphere, leading to an increase in greenhouse gases and potentially forming long-lasting contrail cirrus clouds (linear clouds formed by water vapour and exhaust particles).(4) When including these non-CO2 effects, aviation contributed to 4% of the global temperature increase since pre-industrial times.(5)
The climate impact of aviation is projected to rise by 200%-360% by 2050, even with maximum use of lower-carbon alternative fuels.(6)
What's the solution?
The solution to reducing carbon emissions in air travel involves several key strategies. First, allowing only economy class significantly lowers CO2 emissions per passenger due to lighter and more numerous seats and fewer amenities. Second, taking direct flights and best itinerary(7) minimises the fuel-intensive takeoff and landing stages. Third, fuel-efficient aircraft offer improvement through advanced technology, that can greatly reduce in-flight energy use. Finally, choosing more efficient airlines that maximise seating capacity, have high load factors and improve operational efficiency, reduces emissions further.(8)
Point of attention
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Point of attention
Radiative forcing: Condensation rails of water vapor generated by planes contribute to the formation of cirrus clouds. Those clouds trap outgoing infrared radiation more effectively than they reflect incoming solar radiation, participating to warming effect. When calculating CO2 emissions from air travel, the Radiative forcing (RF) metric is added.(9) Studies show that their effect is equivalent to double or even triple the CO2 emissions from aviation.(10) This means that over 60% of aviation’s impact on global warming could come from non-CO2 effects.(11)
Key actions
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#1 Fly economy class
Flying business class emits 3 times more CO2e emissions per passenger than economy class (and 9 times more in first class). Economy class, with smaller, lighter and less numerous seats, make each passenger account for a lesser portion of the whole plane’s carbon emissions. There are less amenities, less extra services and less baggage allowance, further adding to the plane’s total weight. (see “economy tickets only” factsheet).
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#2 Prefer direct flights
Takeoff and landing are fuel-intensive. During takeoff, aircraft engines operate at maximum thrust, consuming a substantial amount of fuel to gain altitude. Similarly, landing requires considerable fuel to control descent and maintain safe speeds. That is why direct flights significantly reduce emissions (see “direct flights” factsheet)(16).
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#3 Favour more efficient airlines
Airline efficiency is determined by factors such as aircraft fuel burn, engine type, winglets, seating and cargo capacity, passenger load factor, and the freight share of total payload. Some airlines are managed in a more efficient way than others,(17) resulting in fewer emissions per passenger.(18) However, the most critical factors remain aircraft fuel burn and seating density.(19)
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#4 Use search engines that make the climate impact transparent
Use search engines that provide an estimation of greenhouse gas emissions per flight. For example, the travel impact model provides an estimation of emissions per seat/passenger for each flight by integrating factors such as flight origin and destination, aircraft type, cabin class and seat configuration, load factors, and average aircraft utilisation. Google flights uses this model, but note that non-CO2 effects are not yet included (radiative forcing) and emission data will have to be adjusted for reporting purposes.
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#5 Adapt the booking process
Whether flights are booked directly by staff, through an internal department, or a travel agency, make sure that emissions per flight are showcased and taken into account in the final choice. Adapt the booking process to privilege less-emitting itineraries, through both voluntary and compulsory measures (showing less emissive itineraries first, oblige staff to privilege least emissive routes, allow for a certain price increase for direct flights, etc).
To consider
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Potential co-benefits
- Cost savings: Efficient airlines often have lower operational costs, leading to more competitive ticket prices. Choosing economy class also offers additional savings.
- Encouraging sustainability: Favouring efficient airlines creates demand for more sustainable practices across the industry.
- Health benefits: Globally, reducing air travel emissions decreases particulate matter and noise pollution, benefiting public health.
- Improved efficiency: Opting for direct flights reduces travel time, eliminates baggage transfers, and lowers the risk of missed connections.
- Employee well-being: While economy class might be less comfortable for long journeys, direct flights can leave employees more rested upon arrival.
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Success conditions
- Leading by example: Managers and leaders should demonstrate their commitment by choosing less emissive flight options.
- Updated travel policy: The organisation’s travel policy must incorporate the preference for low-emission flights and ensure compliance.
- Budget management: The higher costs of direct flights can be offset by flying economy class or reducing the number of trips. Booking early also helps manage expenses.
- Raising awareness: Engaging leadership in the decision-making process is key to ensuring buy-in and broader organisational acceptance.
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Prerequisites & specific considerations
- Availability: Direct flights or routes with more efficient airlines may not always be available.
- Policy integration: Implementing this solution requires adjustments to the travel policy and booking tools.
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Potential risks
- Increased booking time: Selecting more efficient routes or airlines may require additional effort during the booking process.
- Higher costs: Direct flights are often more expensive than connecting options.
- Employee comfort: Some employees may perceive a downgrade from premium to economy class as a loss of benefits.
Tools and good practices
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Climate Action Accelerator, Travel toolkit, 2024
The Climate Action Accelerator has developed a professional travel toolkit to help organisations implement their travel emissions reduction target.
Explore here -
Google flights, Integrating emission data
Google flights is a tool for choosing the least emissive option in the booking process. It is based on the Travel Impact Model. It calculates estimations of CO2 emissions based on factors such as flight distance, aircraft type, and passenger class. However, the emissions from the calculator do currently not consider non-CO2 effects (radiative forcing index, RFI). For the carbon footprint calculation, data would have to be adjusted for the RFI.
Explore here -
Atmosfair, Airline efficiency ranking, 2018
Atmosfair uses a rigorous methodology to rank airlines based on their CO2 efficiency, providing a valuable tool for travelling and decision making, with airline ranking from A to G.
Explore here -
ICCT, Transatlantic airline fuel efficiency ranking, 2017
This document facilitates organisations’ choice of airlines with greater fuel efficiency, ranking them based on various factors such as passenger load, type of aircraft used, load factors, etc. Overarchingly, this is a guide to help determine which airlines to prioritise in travel decision-making.
Explore here
To go further
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Carbone4, Preconceived ideas on aviation and climate, 2022
The webpage describes the impact of aircrafts on climate change and defines topics such as non-CO2 effects and the increasing emissions from air cargo. It explains how the different technological advances like fuel efficiency and alternative fuels are fundamental while still emphasising on the need to reduce air traffic growth and behavioural change to meet climate goals.
Explore here -
Stay grounded website, 2024
Stay Grounded is a network of over 200 associations campaigning for a reduction in air transport and its negative effects on climate and health. Their website gathers information and constructive critiques on climate policies throughs a variety of factsheets, reports, guides, discussion papers and case studies.
Explore here -
IEA, Aviation, 2024
The International Energy Agency provides facts and figures on Aviation while tracking the progress made by the industry in relation to the Net Zero Emissions by 2050 Scenario. The website gathers simple information on technical measures related to low-emissions fuels, improvements in airframes & engines, operational optimisation and narrates the related policy developments.
Explore here -
Future Tracker, Flight class and Its Impact on your carbon footprint, 2023
The document lays out the reasons for the difference in CO2 emissions between first, business, and economy class tickets. Presented as a “simple opportunity” to further incentivise behaviour change.
Explore here
Acknowledgment
Last updated 25 August 2024.
Share your success stories, suggestions, and comments with us! contact@climateactionaccelerator.org
Featured
Professional travel
Economy class tickets only
Travel policy
Train travel
Direct flights
Flightless employee benefits package
Sources
(1) International Panel on Climate Change, ‘Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change’, chapter 10.5.1, 2022. Available here (accessed 21 August 2024).
(2) N. Dolsak, ‘Different approaches to reducing aviation emissions: reviewing the structure-agency debate in climate policy’, Nature Portfolio, 2022. Available here (accessed 21 August 2024).
(3) Climate Action Accelerator, ‘Roadmap for halving emissions in the humanitarian sector by 2030 a path to climate-smart humanitarian action’, 2024. Available here (accessed 21 August 2024).
(4) C. Lopez de la Osa, ‘Non CO2 effects of aviation : time to finally address aviation’s full climate impact’, T&C, 2022. Available here (accessed 21 August 2024).
(5) M. Klower, ‘Quantifying aviation’s contribution to global warming’, Environmental research, 2021. Available here (accessed 21 August 2024).
(6) Carbon Brief, ‘Explainer: The challenge of tackling aviation’s non-CO2 emissions’, Clear on Climate, 2017. Available here (accessed 21 August 2024).
(7) S. Zheng, D. Rutherford, ‘Variation in aviation emissions by itinerary: The case for emissions disclosure’, The ICCT, 2021. Available here (accessed 21 August 2024).
(8) S. Amant, N. Meunier, C. Mallet, M. Subtil, B. Nossek, L. Delage, ‘Preconceived ideas on aviation and climate’, Carbone4, 2022. Available here (accessed 21 August 2024).
(9) IPCC, ‘Aviation and the Global Atmosphere’, Reports, 1999. Available here (accessed 21 August 2024).
(10) S. Amant, N. Meunier, C. Mallet, M. Subtil, B. Nossek, L. Delage, ‘Preconceived ideas on aviation and climate’, Carbone4, 2022. Available here (accessed 21 August 2024).
(11) Future cleantech architects, ‘The basics and the gaps’, Aviation, 2024. Available here (accessed 21 August 2024).
(12) S.Zheng, D. Rutherford, ‘Variation in aviation emissions by itinerary: The case for emissions disclosure’, The ICCT, 2021. Available here (accessed 21 August 2024)
(13) S. Amant, N. Meunier, C. Mallet, M. Subtil, B. Nossek, L. Delage, ‘Preconceived ideas on aviation and climate’, Carbone4, 2022. Available here (accessed 21 August 2024).
(14) Economy class: 79 gCO2 per pkm vs business class: 228 gCO2 per pkm. GHG Protocol, ‘Defra emissions factors’, 2021. Available here (accessed 21 August 2024).
(15) B. Graver, D. Rutherford, ‘Carbon intensity gap surged to a new high of 63% for transatlantic carriers in 2017’, The ICCT, 2018. Available here (accessed 21 August 2024).
(16) Climate Coalition, ‘Travel’, GCC, 2024. Available here (accessed 21 August 2024).
(17) B. Graver, D. Rutherford, ‘Carbon intensity gap surged to a new high of 63% for transatlantic carriers in 2017’, The ICCT, 2018. Available here (accessed 21 August 2024).
(18) Atmosfair, ‘Atmosfair Airline Index’, 2018. Available here (accessed 21 August 2024).
(19) T. Johnson, A. Murphy, A. Kharina, A. Smorodin, ‘Transatlantic airline fuel efficiency ranking’, The ICCT, 2018. Available here (accessed 21 August 2024).
Credits
Cover photo: Cottonbro/Pexels