Photo: Russ Heinl/Shutterstock

This Small Change Could Cut Aviation's Carbon Footprint by 35 Percent

Sustainability Airports + Flying
by Tim Wenger Mar 25, 2024

Recent studies published in journals including Science Direct and MDPI have shown that reducing the carbon footprint of air travel by as much as 35 percent could be as easy as rerouting the trajectory certain flights to fly above or underneath parts of the atmosphere where their path releases the most condensation trails, or contrails, in the sky.

While the majority of carbon emissions in the airline sector result from burning jet fuel, the contrails formed by the release of particulate matter, water vapor, and heat from planes form cirrus clouds that effectively act as a blanket trapping radiation in the atmosphere, the studies show. This results in about a third of aviation’s emissions, or about one percent of total carbon emissions globally.

The studies found that between two and 10 percent of flights account for the vast majority of contrails. That’s because these trails of condensation occur primarily in humid and icy parts of the atmosphere. By rerouting flights that pass through these areas, much of that “heat blanket” could be avoided.

In 2023, the New York Times reported on data showing that in many cases, pilots could be directed to fly over or under parts of the atmosphere where they’re most likely to produce contrails. What’s more, doing so wouldn’t cost airlines much money. Airlines could feasibly reduce 73 percent of contrails with just a 0.11 percent increas, according to reporting in MIT Technology Review.

Why the added fuel burn could be worth it

Burning more fuel releases more emissions, but the paper’s coauthor Marc Shapiro told MIT Technology Review, “ . . . what we’re showing in this paper is that the added fuel burn is a lot less than we expected.”

This is a point that deserves more attention. Jet fuel is nearly as flammable as diesel and is the primary source of carbon emissions in both commercial and non-commercial aviation. However, due to the small amount of extra fuel that would need to be burned to avoid creating contrails — far less than what is burned during take-off and landing of the flight, in most cases — the climate impact of this could be huge. This is especially true at scale, and played out over a multitude of years.

Even though electric airplanes and more efficient airplane design builds are under development, decarbonization of commercial flights is decades away, if it’s even possible at all. Unless humanity is going to stop flying entirely, small steps like reducing contrails will prove to be pivotal moments in making this high-impact industry slightly more sustainable.

Making a small portion of flights even a little cleaner could have a massive impact on the overall climate impact of aviation, which accounts for about four percent of humanity’s total carbon emissions and is among the most challenging industries to decarbonize.

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