In this episode of our ‘Sustainability in the Air’ podcast, Matteo Mirolo, Director, Strategy and External Relations at Contrails.org, speaks with SimpliFlying’s CEO Shashank Nigam about how contrails — those white lines we see trailing behind aircraft — contribute significantly to global warming and how the aviation industry can address this often overlooked aspect of climate impact.
Contrails.org is a science-led nonprofit initiative launched this week by Breakthrough Energy. The platform is focused on transforming contrail research into practical climate action, and brings together academics, industry practitioners, policymakers and civil society to catalyse work on contrail mitigation. With three core pillars – science, technology, and adoption – Contrails.org coordinates strategic research, develops open-source models and tools, and fosters incentives for implementing solutions across the aviation ecosystem.
Here are the key highlights of the conversation:
What contrails are and their climate impact (2:33)
The mission of Contrails.org (4:48)
Airline trials for contrail avoidance (8:51)
Cost implications of contrail avoidance (13:55)
Implementing contrail avoidance in airline operations (16:27)
Strategic vs. tactical approaches to contrail management (19:34)
Contrail management and Paris Agreement goals (22:36)
Rapid Fire! (26:06)
Keep reading for a detailed overview of the episode.
Why contrails matter in aviation’s climate impact
Contrails, or condensation trails, form when soot and water vapour emitted from aircraft engines in cold, humid atmospheres condense around soot particles and freeze into ice crystals. While they might look harmless or even beautiful in the sky, these ice clouds act like greenhouse gases, trapping radiation emitted from Earth.
While contrails can have a cooling effect during the day by reflecting solar radiation, at night, without any sunlight to reflect, they trap outgoing heat from the Earth, resulting in a substantial net warming effect.
This concerning climate impact presents a more immediate opportunity for mitigation compared to other aviation emissions, says Mirolo, with contrail mitigation offering several advantages:
Unlike CO2 which stays in the atmosphere for centuries, contrails typically dissipate within hours or days, meaning that mitigation actions have an immediate climate benefit.
Only a small percentage of flights create warming contrails. Moreover, the geographic concentration of the problem – primarily in Europe, North Atlantic, and North America – makes targeted solutions feasible.
Contrail mitigation can be implemented using existing aircraft and infrastructure, without waiting for fleet renewals or new technology deployment.
With sustainable aviation fuel (SAF) in scarce and expensive supply, and zero-emission aircraft still years away, contrail mitigation represents one of the few available modalities for the aviation industry to address its climate impact.
5 takeaways from the conversation
1. Contrails.org: A science-led collaborative initiative
Contrails.org is a newly launched initiative by Breakthrough Energy that aims to transform contrail research into practical climate action. Its approach is structured around three fundamental pillars:
The first pillar focuses on science, which Mirolo emphasises as “the most important factor.” This involves coordinating and sponsoring research to deepen understanding of contrail impact, including developing more accurate forecasting methods and impact measurements. The scientific foundation ensures that all subsequent actions are grounded in rigorous evidence.
The second pillar centres on technology and demonstration of feasibility at scale. As Mirolo explains, “We are working to develop open-source models, tools, and protocols for contrail avoidance, and validate them through trials with airlines as well as air navigation service providers.” This approach aims to bridge the gap between theoretical understanding and operational implementation.
The third pillar addresses adoption, focusing on several key aspects: raising awareness about contrails’ climate impact and mitigation potential, resolving system-level hurdles within the aviation ecosystem, and fostering appropriate incentives for widespread adoption. This component recognises that technical solutions alone are insufficient without corresponding behavioural, operational and policy changes.
Contrails.org aims to position itself as an open, collaborative space. Mirolo describes it as “a tent under which people can come and put their furniture,” emphasising that as a non-profit, its sole objective is to solve the contrail problem. This collaborative ethos reflects the understanding that effective contrail management requires coordinated effort across the entire aviation sector.
2. The balance of costs and climate benefits
A critical question for airlines considering contrail avoidance is the potential cost, particularly in terms of additional fuel burn. While precise figures are still being researched through practical demonstrations, early studies suggest the impact could be minimal.
“One of the papers published last year forecasted an additional 0.11% fuel burn across the fleet, which would be good news in terms of the very low financial impact for an airline,” Mirolo notes, though he emphasises the need for more real-world data to confirm these projections.
When comparing contrail management to decarbonisation solutions like SAF or future propulsion technologies, Mirolo mentions its cost-effectiveness:
“Compared to the costs of SAF, other emerging technologies, and future propulsion systems, it’s likely that contrail management will be much cheaper by orders of magnitude. I’m hopeful that creating the right incentives to make this feasible will be challenging, but realistically achievable.”
However, Mirolo emphasises that contrail mitigation isn’t an alternative to other climate solutions but rather a complementary approach: “It’s not a choice between SAF and contrails – we need both. However, in an era where everyone is focused on cost-efficiency, it’s important to highlight that contrail management is likely to be very cost-effective.”
3. Implementation challenges and opportunities
Implementing contrail management in daily airline operations requires careful consideration of workflows and systems integration. The ideal scenario, according to Mirolo, would be a fully automated system that treats contrails similarly to how airlines currently handle turbulence or significant weather events. “The goal is to streamline the process so there’s no added workload or extra adjustments needed from airlines,” he explains.
The contrail mitigation process involves two key steps: strategic planning before the flight by dispatchers, and tactical adjustments during the flight by pilots. Mirolo notes that most efforts currently focus on the strategic level, where meteorological and flight data are used to forecast potential contrail formation. These forecasts then inform flight planning algorithms, allowing for route optimisation that takes into account fuel efficiency, weather and contrail avoidance.
The aviation ecosystem’s collaborative effort is crucial here, requiring cooperation between airlines, air navigation service providers, and technology developers.
As Mirolo notes, “We need airlines to develop the expertise and operational concepts to implement this. At the same time, air traffic control needs to continue the work already underway in some flight information regions, where significant efforts have gone into training controllers and building systems for contrail management.”
4. The targeted approach to contrail management
What makes contrail mitigation particularly promising is that it can achieve promising results by focusing on a small subset of flights, as just 5% of flights produce nearly 80% of aviation’s contrail warming effect.
“The fact that a small proportion of flights cause most of the warming impact from contrails is actually good news,” Mirolo points out. “This means we only need to intervene on flights with the most significant impact, which are primarily concentrated around Europe, the North Atlantic, and North America.”
The targeted approach also extends to specific flight conditions. Contrails form only in ice-supersaturated regions (ISSRs) of the atmosphere – areas where the relative humidity with respect to ice exceeds 100%. Here, the air is cold and humid enough for water vapour to condense and freeze around soot particles emitted from engines. However, these regions constitute a relatively small portion of the atmosphere, and not all flights passing through them generate warming contrails. Additionally, night-time contrails have a more significant warming effect than those formed during daylight hours, as they only trap heat without reflecting any solar radiation.
Flight altitude adjustments offer a particularly effective mitigation strategy. Research indicates that relatively small vertical adjustments – as little as 2,000 feet in some cases – can make the difference between forming persistent warming contrails and avoiding them entirely. This precision allows for minimally disruptive changes to flight operations while maximising climate benefits.
5. The pioneering spirit needed for climate action
The challenge of contrail mitigation exemplifies how aviation can combine scientific rigour with ambitious vision to address climate change.
“Contrail management will be crucial to meeting the Paris Agreement goals,” says Mirolo. “While its contribution may seem modest, the path to achieving the Paris targets won’t rely on a single solution. It will take a series of effective measures working together. Contrail management is one of them – it’s quick to implement, has an immediate impact, and is cost-effective.”
He emphasises that climate solutions won’t come from a single silver bullet but from multiple efficient measures working in concert. The challenge calls for what Mirolo describes as a “moonshot approach” combined with a pioneering spirit reminiscent of aviation's early days: “If we tap into that adventurous mindset, it will help drive the mission to clean aviation.”
Momentum is already building, with airlines like American Airlines and TUI conducting trials, and air navigation service providers enhancing systems for contrail management. Continuous improvement in forecasting accuracy, verification capabilities, and operational integration will be key to scaling up these efforts.
Looking ahead, contrail mitigation will require effective collaboration across the aviation ecosystem. Contrails.org aims to facilitate this as an open platform where stakeholders can work together. As Mirolo states: “Our sole goal is to solve this problem. We’re eager to collaborate with anyone committed to addressing warming contrails,” Mirolo concludes.
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