A recently published study from a team of scientists purports that if just 2% of the world’s scheduled flights changed their flight paths to reduce contrails, the result would cut the airline industry’s carbon footprint by more than half.
The study was published by a collective of scientists from the Imperial College London, which can be viewed here, and states that reducing contrails - the ice cloud formed by an aircraft as water vapor condenses around small dust particles - is central to the problem-solving.
Contrails act to both reflect the sunlight entering the earth’s atmosphere when they’re frozen, but can also block heat from escaping with its greenhouse effect.
“So, if we were to stop producing contrails, the effect of contrails would go away the next day,” says Marc Stettler, one of the researchers who put together the study. “It’s a way that the aviation industry can really quickly address its impact on climate change,” he added.
A study from MIT showed that contrails accounted for just under 15% of climate and air quality damages per unit of aviation fuel burn.
According to CNN, “flying an airplane higher or lower could help get rid of contrails because they only form in thinner areas of atmosphere, with high humidity - so it’s theoretically possible to avoid them and reap the eco-benefits.”
Stettler continued to explain that “what we show is that you can make minor modifications to the altitude of a flight and avoid that flight forming a contrail.”
The team of researchers ran their hypothesis through a number of computer simulations using the data made available to them from Japanese airspace, experimenting with projections on what would happen if they were to fly higher and lower to avoid producing contrails. Despite the rise in fuel use if a plane were to fly higher than its original flight path, researchers say this is a marginal increase - 0.1% - and the benefit would outweigh the extra fuel if the contrails were reduced significantly.
CNN’s report also quotes Andrew Heymsfield, a senior scientist with the National Center for Atmospheric Research, who acknowledged the science, but questioned its relevance to the real-world operations of the airline industry.
“The question is, how would they find what those altitudes are [that] would be less amenable to the development of a contrail?”
Heymsfield theorised that a new set of instruments would need to be installed on aircraft fleets that specialise in reading humidity. “Those would have to be developed and deployed on an aircraft so that a 3D depiction of those altitudes could be developed from aircraft which collect those data and then transmit it to the ground.”
“Otherwise, I don’t know how aircraft air controllers would know where to allow the aircraft to fly,” he added.