modifying flight plans could reduce these climaticidal phenomena – Libération

The share of white lines created by planes in the sky in global warming could be reduced by changing certain flight plans, confirms an analysis published this Wednesday, November 13 by a European NGO. “By slightly modifying the flight paths of a small part of the global fleet, the climate impact of contrails could be halved before 2040,” indicates this assessment carried out by Transport & Environment. The association estimates the cost of this measure at “maximum 4 euros per passenger for a transatlantic flight”.

The report offers “avoidance strategies” to prevent the creation of contrails (often called contrails) “which last for several hours” et “have a warming effect, mainly at night, when they prevent terrestrial radiation from escaping into space”details Jérôme du Boucher, aviation manager of the organization, to AFP. Concretely, a pilot should adapt his flight plan to pass “either a little above or a little below an atmospheric air mass that has been identified by weather models”knowing that wetter and colder air masses are favorable to the creation of these condensation trails, according to this expert.

A small part of the journeys concerned

The document indicates that only 3% of flights generate 80% of the warming linked to these contrails. The trajectory changes requested by the NGO would therefore only take place on a limited number of journeys and during only a small part of the journey. The surplus fuel used by planes would only represent 0.5% of the kerosene consumed by the entire world fleet in a year.

The subject of changing the trajectory of a fraction of flights is already under study at Air France, as reported by AFP at the end of September. In this company, 4% of flights are responsible for 80% of the impact of contrails on global warming, underlined Irène Boyer-Souchet, in charge of the file at Air France. More than 3,000 observations were made by in-house pilots over a year and a half, with the aim of helping Météo France improve its forecasts of risk areas so that they could possibly avoid them. American Airlines pilots carried out seventy test flights above or below risk zones using satellite images, meteorological data, software models and prediction tools. the help of artificial intelligence. A 54% reduction in contrails was noted.

Soot and ice crystals

Classified as non-CO2 emissions from aircraft, contrails forming at high altitude in cold, humid areas called ice supersaturated regions during the combustion of kerosene are increasingly studied by scientists and industry. . The soot particles become encapsulated in ice crystals which form white lines transforming into cirrus clouds, filament-shaped high-altitude clouds. Cloud sails trap some of the heat rising from the Earth, preventing it from being radiated out of the atmosphere, and therefore act as a greenhouse gas by causing net warming.

According to a study on the contribution of aviation to climate change published in 2021 in the scientific journal Atmospheric Environment, these sails could represent up to 57% of the sector’s impact on global warming, much more than CO2 emissions due to fuel combustion. But emissions linked to white lines have a shorter lifespan in the atmosphere than those due to carbon dioxide and their effect on global warming could disappear quickly if solutions were found to avoid them. According to a report from the University of Cambridge published in September, accelerating the deployment of a global system against contrails could even reduce the impact of aviation on the climate by 40%. Which, given the saturation of airspace, would first require setting up a coordinated system at the planetary level.