No, this is not an article looking into the "chemtrail" conspiracy theory that claims those puffy white plumes streaming out from behind jets in the sky are from governments controlling the weather. It is, however, weather, or should we say climate, related. Aviation impacts global warming in more ways than through its carbon footprint. One way it does this is through the formation of contrails. And the pilots of the British Air Line Pilots’ Association (BALPA) recently warned climate policymaking is not taking them sufficiently into account.

Pilots as the climate conscience of the industry

BALPA has helped shape the UK government's upcoming Jet Zero Strategy, due in summer this year. However, the trade organization believes that the strategy, soon to be published, underplays the significance of aviation's non-CO2 effects on the climate, including those of contrail formation.

BALPA says it has been continuously campaigning for a comprehensive research trial into the impact of contrails and says it hopes for funding for such a project to be included in the strategy. Jeremy Thomson, Chair of BALPA’s Environment Study Group, commented on the overall ambitions,

BALPA wants to see a thriving future for the aviation sector in the UK, one that provides jobs for our members and mobility for our population. Yet we are in the midst of a climate crisis and have a moral and legal obligation to ensure our future is a sustainable one.""Pilots have always been the ‘conscience’ of the aviation industry over safety, helping to create the safest mode of transport ever known. BALPA’s efforts in sustainability will be the conscience of the industry with respect to tackling climate change, ensuring effective solutions to preserve the undeniable benefits of air travel to humanity and business.”

Pilots in flight simulator
North America will need the most pilots of any region. Photo: Getty Images.

Significant climate impact

But just how big an impact are we talking about from contrails and, for instance, nitrogen oxide emissions? While BALPA is calling for an extensive research program, there is already substantial academic work on the matter, with estimates that they could account for as much as 50% or even more of aviation's climate impact.

Boeing just recently launched a contrail reduction research partnership, and Etihad has operated several flights where the airline has attempted to reduce contrail formation as much as possible. Sustainable aviation fuels are generally considered to produce less water vapor which leads to the formation of contrails, but air traffic management has a significant role to play.

Discover more aviation news here.

Speaking at the Sustainable Aviation Futures conference in Amsterdam last week, Kinathi Sutopo, who is a consultant for Sustainable Aviation at NLR - Netherlands Aerospace Center, said

"In the research field, quite a big thing is avoiding climate-sensitive areas. So you have certain regions in the atmosphere that are more sensitive to creating contrails. The thing is, however, that these regions can change, because it's very dependent on the atmospheric conditions, time of day, and other factors."

cargo ups 747 contrails
One way to reduce contrail formation would be to fly at lower altitudes in climate-sensitive areas. Photo: Getty Images

Could flying a little lower be a solution?

According to research from the NLR, one way of limiting contrails would be to operate flights at a slightly lower altitude. While this would increase fuel burn somewhat, it would help reduce the non-CO2 impacts, including contrail formation and nitrogen oxide (NOx). Sutopo stated,

"When you're looking at the nitrogen oxides emissions, the lower you fly, the less harmful the impact is. The same goes for water vapor emissions. So in terms of non-CO2 emissions, you'd have a really big win if you could fly a little bit lower than the current optimal cruise altitudes."

How aware are you of the non-CO2 effects of aviation on global warming? Do you think policies are taking them enough into account? Leave a comment below and let us know.