2024-08-07 12:27:46
According to Edward Gryspeerdt of Imperial College London, the findings could help airlines determine which routes to fly to minimize the plane’s condensation footprint. “If we could predict well enough which regions of the atmosphere are producing contrails, we could direct planes around them, reducing that effect.”
Under certain conditions, soot particles emitted by jet engines can lead to the formation of ice particles at the back of an aircraft, forming clouds known as jet contrails, which have a general warming effect. It is estimated that as much as half of the climate warming effect caused by aviation is not related to carbon dioxide emissions, but to condensation footprints.
How long aerodynamic clouds persist has a large impact on how much climate warming they cause – but their persistence is difficult to study. Gryspeerdt’s team combined flight data and satellite observations to determine the associations between specific aircraft and contrails and how aircraft type relates to contrail persistence.
In the past, this was only done on a small scale because it was done manually. But with the help of artificial intelligence, the team was able to analyze 64,000 flights. It found that private jets and more economical jets, which typically fly at about 38,000 feet (12 kilometers), a kilometer higher than other planes, are more likely to create longer-lasting contrails. “It was not what we expected,” says E. Gryspeerdt.
Not all soot particles emitted by an aircraft turn into ice particles, he said. The team believes that as the plane flies higher, a larger proportion of the soot particles form ice particles, but the overall size of the ice particles is smaller.
Smaller ice particles fall more slowly, so they take more time to fall to regions where the air is relatively warmer, where they sublimate back into water vapor. This means that the condensation trail lasts longer and causes more warming.
But because the properties of these higher-altitude contrails are slightly different, the team can’t say exactly how much warming they’re causing. Therefore, it is unclear whether the additional warming caused by longer-lasting contrails offsets the warming avoided by modern airplanes using less fuel.
All that is clear is that the impact of private jets has been underestimated. “Their climate impact per passenger is even greater than we thought,” says the researcher.
Because contrails are more visible over oceans and the team only had data from one geostationary satellite, they also only looked at flights over the western Atlantic Ocean, around Bermuda.
Gryspeerdt says the findings may not apply to flights further north, such as over Greenland and Iceland, because the air at high altitudes is drier, making contrails less likely to form.
“The study shows that high-altitude aircraft have a significant non-CO2 impact on the climate, primarily through the persistent contrail,” says Krisztina Hencz of the European environmental organization Transport & Environment.
High-altitude flights are mostly used for long-haul flights, she said, but long-haul flights are not covered by the European Union’s program to reduce non-CO2-related climate warming. It also points to the importance of switching to fuels that produce fewer soot particles, she says.
The study is published žurnale „Environmental Letters“. Parengta pagal „New Scientist“.
2024-08-07 12:27:46