A new study reveals that newer commercial planes flying at high altitudes produce contrails that linger in the sky longer than those from older aircraft. This finding complicates efforts to reduce aviation’s climate footprint.
The Contrail Conundrum
Contrails are the thin clouds of ice crystals that form behind aircraft at high altitudes. These seemingly innocent streaks in the sky actually trap heat in the atmosphere, contributing to global warming. In fact, scientists believe contrails may have an even greater warming effect than the carbon dioxide emitted from burning jet fuel.
Researchers from Imperial College London used machine learning to analyze satellite data on over 64,000 contrails from various aircraft flying above the North Atlantic Ocean. Their findings, published in Environmental Research Letters, show that modern aircraft like the Airbus A350 and Boeing 787 create more persistent contrails than older commercial planes.
Dr. Edward Gryspeerdt, the study’s lead author, explains: “It’s common knowledge that flying is not good for the climate. However, most people do not appreciate that contrails and jet fuel carbon emissions cause a double whammy warming of the climate.”
Higher Altitudes, Longer-Lasting Contrails
Modern aircraft are designed to fly at higher altitudes, typically above 38,000 feet, where the thinner air reduces drag and improves fuel efficiency. While this design choice does reduce carbon emissions per passenger, it also means these planes create contrails that take longer to dissipate.
This presents a complex challenge for the aviation industry. As Dr. Gryspeerdt notes, “Newer aircraft are flying higher and higher in the atmosphere to increase fuel efficiency and reduce carbon emissions. The unintended consequence of this is that these aircraft flying over the North Atlantic are now creating more, longer-lived, contrails, trapping additional heat in the atmosphere and increasing the climate impact of aviation.”
The study did identify one potential solution: reducing soot emissions from aircraft engines. Modern engines typically emit fewer soot particles, which can help shorten the lifetime of contrails. This is the first study to confirm this effect using real-world observations rather than models.
Dr. Marc Stettler, co-author of the study, states: “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.”
The research also revealed surprising findings about private jets. Despite their smaller size, these aircraft create contrails as often as much larger commercial planes. This is likely due to the extremely high altitudes at which private jets typically fly, adding to concerns about their disproportionate climate impact.
Why it matters: This study highlights the complexity of reducing aviation’s climate impact. While newer aircraft are more fuel-efficient, their contrails may offset some of the gains made in reducing carbon emissions. As the aviation industry works to become more sustainable, addressing the issue of contrails will be crucial. For consumers, this research underscores the importance of considering all aspects of air travel’s environmental impact, not just carbon emissions.
