Welcome back from the summer holidays, which have been sweaty for most people. Western Europe had its hottest June–July ever. Global sea surface temperatures were the highest ever recorded for July. And with a strong El Niño building in the Pacific, Berkeley Earth now gives 2026 roughly a 70% chance of ending as the warmest year on record.
This is the reason Blue Lines exists. Contrail avoidance will not fix the climate. But it is one of the very few levers that can remove 1–2% of human-caused warming within years rather than decades, at low cost, with technology that already works. Summers like this one are reminders of why we are doing this and a nudge to act now.
🇬🇧 Operation Blue Skies: the biggest contrail trial yet
The UK just announced what is likely to be the most ambitious contrail avoidance trial to date.
Operation Blue Skies is the first trial to test contrail avoidance across an entire oceanic airspace. It takes place in Shanwick, the eastern half of the North Atlantic, which is controlled by the UK’s air navigation service provider, NATS. More than 1,000 flights a day pass through Shanwick, and the region alone accounts for roughly 5% of global contrail warming.
Contrail forecasts will be fed directly into the air traffic control system, and aircraft will make small altitude changes on 20 to 40 test days during each of two winter windows (2026–27 and 2027–28). Google’s satellite imagery and machine learning will then check whether predicted contrails form.
The consortium is a strong one: NATS, Google, Contrails.org, the UK Met Office, Imperial College London and the University of Cambridge, with the UK Department for Transport funding just over half of the £5 million program.
If you want the full picture of where this trial fits in, we have just updated our list of every publicly announced contrail avoidance trial (involving more than 10 flights) past and present, on the Blue Lines website: blue-lines.org/trials. If we are missing one, let us know.
🇪🇺 The EU puts a price on contrails — but is it enough?
On 17 July, the European Commission published its proposal for revising the EU Emissions Trading System for aviation. For the first time, it contains a mechanism specifically designed to reward contrail avoidance.
The headline number is impressive: a reserve of up to 3 million ETS allowances through 2033, worth around €255 million at today’s allowance price of roughly €85, for airlines that use contrail forecasting in their flight planning. An additional small bonus goes to airlines that report non-CO2 effects using in-flight measured data.
We were excited when we first read it. Then our friends at Nexus Lab and Estuaire ran the actual numbers, and the excitement cooled.
The mechanism pays airlines allowances equal to 0.1% of their verified emissions (plus 0.02% for the measured data). Apply that to the 2025 verified emissions of all 584 operators in the EU ETS, and the total comes to about €5.6 million per year — not the €35 million per year the reserve’s annual cap would allow, and nowhere near the €255 million headline.
Comparing these allowances to yearly revenue numbers, Ryanair’s €1.26 million a year is only equivalent to 0.0081% of the airline’s €15.5B revenue. SAS would receive around €203,000, which is 0.0045% of its annual revenue. Many operators would be well below €10,000 in annual allowances. And from that money, airlines would have to pay for software integration, internal work, any external assistance, and extra fuel burned during avoidance maneuvers.
To put the whole thing in perspective: European airlines made a collective net profit of around €11 billion last year, according to IATA. The entire contrail incentive (€5.6M per year) is half a promille of that.
“A contrail incentive worth about what a mid-size airline spends on coffee is unlikely to change how anyone flies”
We welcome the principle and the people behind it. But a contrail incentive worth about what a mid-size airline spends on coffee is unlikely to change how anyone flies. If the EU wants this mechanism used, something closer to 0.5% of verified emissions would be a reasonable starting point. That is still well within the reserve and enough for airlines to begin to notice. We hope the EU will take a close look at that one figure.
🌅 One tip before you book your next flight
Finally, a reminder for everyone now back at their desks and already planning the next trip.
Not all flights are equal when it comes to contrail warming. During the day, a contrail reflects sunlight back into space as well as trapping heat from below, and the two effects partly cancel out. At night, there is no sunlight to reflect, so the contrail only traps heat.
We have posted this graph from RMI before: while persistent contrails from early morning flights are likely to have a slight cooling effect, flights departing in the late afternoon or evening are far more likely to produce warming contrails.
So, until airlines do the avoiding for us: if you have the choice between the 7 am departure and the 7 pm one, the early bird is the better climate choice.
Thanks for reading Blue Lines. Please share with someone who could be interested in aviation and the climate.
Interested in knowing what it takes to implement contrail avoidance (trials) as an airline? We have put together a free guide with support from Contrails.org. It is called Contrail Avoidance in Practice: A Playbook for Airlines, and it is the first comprehensive, practitioner-built guide to getting started, covering governance, tools, dispatch workflows, pilot engagement, cost management, and funding. It can be downloaded here.
To new Blue Lines followers: Welcome.
In 2025, we added 33% more subscribers. It is always a pleasure to have more people interested in the progress of contrail avoidance – the most promising solution to lower aviation’s climate impact and potentially one of the fastest ways to reduce global warming overall.
Go to Blue Lines’ website to explore contrails in depth.
See you soon.
Joachim Majholm,
Blue Lines
I'm surprised Ireland did not join this,
I'd love to combine my idea of matching the Airbus GEESE project with Contrail avoidance project could help better study the atmosphere at different heights and reduce the extra fuel burn penalty.
GEESE fello'fly | Airbus https://share.google/cRvJ4cjpAsG60YwV9