January 8, 2025
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The other impacts of aviation on the climate
The global impact of aviation on climate changeIn addition to CO₂, aviation has other “non-CO₂ effects” on climate change. These effects result from complex interactions between aircraft emissions and the atmosphere. They are mainly related to the formation of contrails (short for condensation trails), and also include the emission of nitrogen…significant warming impact, especially in the short-term,of the same order of magnitudeas CO₂ emissions. Air France is actively committed to identifying and implementing solutions to reduce non-CO₂ effects, and thus minimizing the climate impact of its flights. Image Climaviation, action de recherche sur l’aviation et le climat © ClimaviationWhat is the climate impact of non-CO₂ effects ?The latest scientific research on the cumulative effects of past aviation emissions from 1940 to the present day has highlighted the significant impact of non-CO₂ effects. These accounted for two-thirds of aviation’s radiative forcing in 2018, meaning the change in the Earth’s energy balance.…Contrail formationCondensation trails, or contrails, are responsible for at least 80% of the non- CO₂effects.Contrail formationThe white streaks that form in the sky behind an aircraft are known as condensation trails (contrails). When an aircraft passes through sufficiently cold and humid atmospheric conditions, the water vapor in the air transforms into an artificial cloud, the formation of which is facilitated by the…Contrails persist in certain risk areasBut in a super-saturated humid atmosphere, the contrails will persist, gradually spreading into sprawling cirrus clouds, which can linger for up to ten hours. They have a twofold impact on the climate – a cooling effect due to the reflection of solar radiation, and a greenhouse effect, which warms…IAGOS partnership: An aircraft equipped with scientific sensorsSince 2013, in partnership with the CNRS, Air France has been taking part in IAGOS (In Service Aircraft for a Global Observing System), a European research infrastructure. Air France has equipped an Airbus A330 with scientific sensors that measure greenhouse gases and humidity at high altitudes in…Collaboration with Météo France: A more reliable prediction of persistent contrail-prone areasCurrent weather forecasts do not allow for anticipating with sufficient precision the areas where persistent contrails will form along a flight path. Since 2021, Air France has been working with Météo France to improve the prediction of these risk areas. Within this framework, Air France has…Participation in the European research project CICONIAThe CICONIA European project combines a scientific and operational approach to determine the most effective solutions for reducing the climate impact of non-CO₂ effects, and to implement them on a large scale. The project encompasses the entire ecosystem – research bodies, weather services,…Future solutions to reduce contrailsA small number of flights are believed to account for most of the climate impact caused by contrails. In 2019, on a global scale, less than 3% of flights were responsible for 80% of the climate impact related to contrails ( Imperial College ). Detecting these flights in advance will, in the future…Avoiding flying in areas at riskOne promising strategy is to modify the flight path to avoid creating warming contrails. In most cases, this solution results in additional fuel consumption, and consequently additional CO₂ emissions. These flight path changes will therefore only be implemented if they are globally beneficial for…Improving fuel qualityCertain fuel components, known as aromatics, play a role in soot production. Removing part of these components from fossil fuels, or using sustainable aviation fuels (SAF) that are naturally free of them, reduces the formation of soot, which could lead to a significant reduction in contrail…Your questionsWhat is the future impact of a flight on the climate? And how can we effectively compare CO₂ with non-CO₂ effects?Radiative forcing does not directly provide the CO₂ equivalent of non-CO₂ effects. To estimate the future climate impact of a flight taken today, there are various methods that consider the timescales over which these phenomena operate (hundreds of years for CO₂, compared to hours to years for non-…Has the Air France group already implemented solutions to reduce condensation trails?The main short-term solution for reducing non-CO₂ effects is to modify flight paths to avoid areas conducive to contrail formation. But this solution is not mature enough to be deployed on a large scale. The main risk is to implement unnecessary route adjustments which could be harmful to the…What is the impact of nitrogen oxides (NOx) on the climate?Nitrogen oxides (also known as NOx) are formed at high temperatures during combustion in engines. At low altitudes, they degrade air quality and have an impact on human health. When emitted at high altitudes, NOx contributes to global warming by forming ozone, while it has a cooling effect by…