The 1970s. Disco music and flashy shirts were on the rise. But so was the use of fossil fuels, and a group of scientists sounded the alarm bell. The carbon emissions of these fuels could have disastrous consequences for our Earth’s climate.
We know what came after. Oil companies captured the narrative, denied the problem, deflected attention, and delayed action. They managed to silence the alarm bell and kept pumping oil, gas and coal, racking up trillions of dollars while breaking down the climate.
Fast forward to 2023. We can very much feel the heat of climate change, as scientists predicted. (Almost) no one denies it anymore, and action is speeding up.
We could think that, if scientists sounded a new alarm about a climate issue, we would try our best to avoid the same mistake. We would take bold, decisive action to solve the problem and avoid a further worsening of global warming.
Well…it looks like the aviation industry thinks otherwise.
Carbon emissions are just the tip of the iceberg of aviation climate’s impact. Other emissions from aircraft engines (soot, water vapour, sulphur, nitrous oxides) create changes in the upper atmosphere, such as persistent contrails or the generation of greenhouse gasses. Known as “non-CO2 effects”, these changes cause additional warming, which is at least as bad, and up to three times worse, as aviation’s carbon emissions.
Instead of looking at the issue in the face and solving it, the aviation industry seems to be carefully following big oil’s playbook.
First, failing to acknowledge the problem exists. Non-CO2 effects have been researched for decades, and their impacts have been well known for more than 20 years. However, while the aviation industry has created a big hype around decarbonisation, SAFs or zero emission technologies, it is quite rare to find any mention of non-CO2 effects on websites, sustainability reports, conferences or press releases.
Then, by deflecting attention. Even when non-CO2 effects are recognised, many industry stakeholders claim that it is essential to focus on decarbonisation first, although there is no reason why we cannot tackle both problems in parallel.
Finally, by delaying action. Scientific knowledge may have some limitations, but it is the main driver of human progress.Overstating the uncertainties of aviation’s non-CO2 effects amounts to cherry picking arguments to justify inaction.
But let’s get three things right:
- The science is clear enough about the importance of the problem. In spite of the uncertainties, we know that non-CO2 effects have a climate impact at least as important (and probably worse) than CO2. Is the aviation industry doing at least the same to tackle non-CO2 as it is doing to decarbonise? The answer: nowhere near enough.
- Solutions do exist, and we do not need to eliminate all uncertainties before acting.
Take contrail formation – the main driver of non-CO2 effects. We already know that less than 5% of flights create 80% of contrails’ warming effect. Minor changes to the flight paths of those “worst offender” flights would minimise contrail formation without a significant disruption of air navigation, and with almost no fuel burn penalty.
Another solution is using sustainable aviation fuels (SAFs), which emit less particles when burnt. This reduces warming from contrail cirrus, and improves air quality around airports. However, SAFs will take time to scale up. In the meantime, we can achieve similar benefits by hydrotreating jet fuels, a technology used for decades by refineries to lower the amount of particle emissions from road and shipping fuels. Climate and health benefits thanks to applying a mature technology: why wait?
- We need a solid policy framework to tackle the problem. It is unlikely that the aviation industry will proactively mitigate non-CO2 effects without binding regulation in place, considering that it has failed to meet most of its own climate targets to date.
The EU is taking steps in the right direction. The emissions trading system (EU ETS) for aviation will introduce a system to monitor, verify and report non-CO2 effects from European flights. However, we cannot stop there: if we want to make a dent to the impact of non-CO2 effects, we need them to be priced under the ETS in the second half of the decade. The price signal would incentivise the adoption of non-CO2 mitigation strategies.
We also need legislation to optimise jet fuel quality by 2025 if we want to be serious about tackling aviation’s climate and health impacts.
I am pretty sure that aviation can do better than big oil. Instead of downplaying the problem or opposing policies and regulations, the industry should show climate leadership to tackle non-CO2 effects with an innovative, can-do attitude. After all, it is arguably the quickest, most cost-effective way to curb aviation’s climate impact. Who would oppose that?
First published in Aviation Week