The aviation industry can potentially halve its climate impact this decade at a low cost
Guest article by Joachim Majholm, founder of US-based non-profit Blue Lines.
While electrification, hydrogen planes, and sustainable aviation fuels hold promise for the future of sustainable aviation, these innovations require substantial investment and may take decades to fully implement.
However, there is an affordable climate solution for aviation that could be realised within this decade: contrail mitigation.
Contrails, those wispy white lines left in the sky by planes, form when water vapour from engine exhaust condenses around soot particles, creating ice crystals. These contrails can sometimes expand into extensive, high-altitude ice clouds.
These cirrus clouds have a dual effect on the Earth's climate: they reflect incoming solar energy during the day 👍 but trap heat during the night 👎. The net effect is that contrails potentially make up about 50% of aviation's climate impact.
The good news
The technology is already available to help airlines steer clear of regions predicted to generate persistent contrails, thus preventing the formation of condensation trails that exacerbate global warming.
Only a fraction of all flights need to be slightly rerouted over, under, or around the predicted contrail weather to eliminate most of the climate warming from these artificially created ice clouds.
A fraction of a percent in extra fuel cost
In August 2023, they released the findings of a collaborative study with Google Research and American Airlines. The study involved practical testing of contrail management. By slightly adjusting flight paths to avoid contrail-prone areas using Breakthrough Energy's software, they reduced contrail formation by an impressive 57%.
However, this comes with a cost that can seem relatively high at first glance.
The flights in the above study used an average of 2% extra fuel (which released 2% more CO2 emissions) to go around the predicted contrail weather. When you spend billions of dollars on fuel, as American Airlines does every year, 2% seems like a substantial extra cost and a lot of extra CO2 emissions.
Here’s the silver lining: The 2% extra fuel burn was only necessary for the few flights that were predicted to produce warming contrail clouds – not the entire fleet.
Several studies have looked closer at the cost of navigational contrails mitigation. At the Sustainable Aviation Futures North America Congress in Houston, Texas, a few weeks back, Marc Shapiro, director of contrails at Breakthrough Energy, mentioned that a new study involving simulating 100,000 flights in collaboration with Austrian flight planning software company Flightkeys resulted in an extra fuel investment of 0.03% to 0.05% on a fleet-wide basis. That number is almost as low as the 0.014% fuel penalty in a 2020 study looking at avoiding contrails over Japan.
It should be noted that both studies look at avoiding the majority of the contrail warming – not all of it.
A no-penalty result has been reported (but not independently verified yet) by Adam Durant, CEO of British company Satavia, while rerouting flights scheduled to produce highly warming contrails with clients KLM Cityhopper and Etihad Airways.
Tiny airfare increases
Fuel accounts for roughly 20% of an airline's expenses. Therefore, to estimate the potential airfare increase resulting from airlines passing on their additional fuel costs for contrail mitigation to customers, we can simply calculate the ticket price multiplied by 20% and then by 0.05%.
Suppose airlines choose to implement contrail mitigation and pass the extra fuel expenses on to passengers:
A short, local flight priced at $150 will only incur an increase of $0.02 (totalling $150.02), while a long-haul flight will see a rise of $0.10, moving from $1000.00 to $1000.10.
It's important to acknowledge that there will be additional expenses, such as implementation costs (software, training, process adjustments, etc.) and ongoing staff costs associated with addressing this issue. Even if those additional costs end up being ten times higher than the cost of the extra fuel, the potential airfare increase would be comparable to a rounding error.
But remember that those few extra cents could significantly cut the aviation industry’s climate impact, maybe by as much as half.
Many prominent airlines have acknowledged the problem – and opportunity – and have started helping researchers, such as by participating in the Contrail Impact Task Force. Some are even involved in real-life contrail mitigation.
Notably, in 2023, IATA, the airline industry's trade association, addressed the environmental impact of contrails for the first time. It’s a heartening start. Let’s hope that much more happens in this area in the near future.
This guest blog was written by Joachim Majholm, the founder of US-based non-profit Blue Lines. Blue Lines aims to educate and communicate about contrails and the climate to speed up the implementation of contrail mitigation for the benefit of our planet. Go to www.blue-lines.org to explore much more about contrails, and sign up for Blue Lines’ newsletter.