A new study, led by scientists at Imperial College London and published in Environmental Research Letters, has found that modern commercial aircraft flying at high altitudes create longer-lived planet-warming contrails than older aircraft.
This revelation comes after the study, which used machine learning, analysed satellite data on more than 64,000 contrails from a range of aircraft flying over the North Atlantic Ocean.
“Newer aircraft are flying higher and higher in the atmosphere to increase fuel efficiency and reduce carbon emissions,” explained Dr Edward Gryspeerdt, lead author of the study and a Royal Society University Research Fellow at the Grantham Institute – Climate Change and the Environment.
However, Gryspeerdt said that an unintended consequence is that the aircraft are now “creating more, longer-lived, contrails, trapping additional heat in the atmosphere and increasing the climate impact of aviation.”
Indeed, this applies to aircraft flying above 38,000 feet, such as the Airbus A350 and Boeing 787 Airliners.
The study’s findings also highlighted the underestimated impact of private jets.
The researchers outlined that this type of aircraft produces longer-lived satellite-detectable contrails despite their lower fuel flow, as they fly at higher altitudes, more than 40,000 feet above Earth.
“Despite their smaller size, private jets create contrails as often as much larger aircraft. We already know that these aircraft create a huge amount of carbon emissions per passenger so the super-rich can fly in comfort,” said Gryspeerdt.
“Our finding adds to concerns about the climate impact caused by private jets as poor countries continue to get battered by extreme weather events,” the author added.
However, the study also found that reducing the amount of soot emitted from aircraft engines, produced when fuel burns inefficiently, could reduce the lifetime of contrails.
“Our study provides the first evidence that emitting fewer soot particles results in contrails that fall out of the sky faster compared to contrails formed on more numerous soot particles from older, dirtier engines,” commented co-author Dr Marc Stettler, a Reader in Transport and the Environment at the Department of Civil and Environmental Engineering, Imperial College London.
Gryspeerdt said that while it’s common knowledge that flying is “not good for the climate,” most people do not appreciate that contrails and jet fuel carbon emissions cause a “double whammy warming of the climate.”
“This doesn’t mean that more efficient aircraft are a bad thing – far from it, as they have lower carbon emissions per passenger-mile. However, our finding reflects the challenges the aviation industry faces when reducing its climate impact,” added the research lead.
Read the full study here.