Civil aviation is a well-known contributor to climate change. As explained by Kieran Tait, a young researcher from the University of Bristol, this represents around 2.5% of global CO2 emissions.2.
However, the figure is misleading: carbon dioxide represents only a third of the pollution emitted by aircraft, the other two thirds are represented by other gases such as nitrogen oxides (NOx), or by contrails (“adversaries”in English), whose role in global warming is often overlooked.
Despite the great climate emergency and relative improvement in efficiency, research aimed at creating “cleaner” aircraft (hydrogen, electric, running on so-called “green” kerosene or fuels described as “sustainable”, etc.) cannot be fulfilled. for a long time.
Air traffic continues to grow despite the crises: Boeing thus plans 82% more planes over our heads by 2041. In line with greater individual discretion and a voluntary reduction of the (many) most unnecessary air journeys, urgent measures should be sought to limit the effects of aviation on the climate.
This is exactly what Kieran Tait and his team proposed in an article recently published in the journal Aerospace – the researcher also sounded the alarm, later, on The Conversation site. According to them, two immediate changes would enable aviation to reduce its climate footprint by 24%.
In the squadron
One of these two changes points directly to NOx. Kieran Tait thus explains that nitrogen oxides interact, at high altitudes taken by airplanes to reduce air resistance, with the atmosphere to burn methane and create ozone.
If the first is a very strong greenhouse gas, the second is also, and the balance is not very good. “Unfortunately, there are NO emissionsx by airplanes causes more warming through ozone production than cooling through methane reduction. This leads to an effect that accounts for 16% of global warming due to emissions.wrote the scientist.
The second change focuses on contrails, which form more easily in a cold and humid atmosphere and which, by trapping the heat released by the Earth’s surface, account for 51% of the total effect in civil aviation.
And as the researcher explained, the difference in CO2 so NO emissionsxlike contrails, directly depends on their interaction with the surrounding atmosphere. So it is theoretically possible to fly the aircraft in conditions that limit the consequences of their non-CO emissions.2and that is what Kieran Tait offers.
According to the research team, changing the usual routes of airplanes to make them better paths, avoiding for example the wettest areas and altitudes that create the most persistent and harmful condensation, could be beneficial for the environment despite a slightly higher consumption of kerosene.
So the shortest route is not necessarily the least polluted: a longer distance of 1% or 2% can, according to some research, reduce the climate consequences of trips by 20%. But that’s not all: Kieran Tait also put on the table the idea of flying planes in formation, instead of alone.
By flying one to two kilometers behind another aircraft, an aircraft can “surf” its intake and reduce CO emissions.2 of about 5%. Better: the accumulation of nitrogen oxide emissions from two devices – or more – will make it possible to reach a concentration threshold beyond ozone which is no longer possible.
Adversaries, competing for atmospheric moisture, may also be limited to these squadron flights. Overall, Kieran Tait calculated, the profit if these new rules were applied now for all air traffic would be 24%.
Not enough to save the planet, but it’s a big impact, and it’s not the most complicated measures to be implemented in the near future.