Civil aviation is a notable contributor to climate change. As Kieran Tait, a young researcher from the University of Bristol explains, it represents around 2.5% of global CO emissions2.
The figure is nonetheless misleading: carbon dioxide represents only one third of the pollution emitted by aircraft, the other two thirds being represented by other gases such as nitrogen oxides (NOx), Where by condensation trails (“contrails”in English), whose role in global warming is often overlooked.
Despite the great climate emergency and relative progress in terms of effectiveness, research aiming to create “cleaner” aircraft (hydrogenelectric, operating with a so-called “green” kerosene Where fuels described as “sustainable”etc.) will not be completed for a long time.
Air traffic continues to grow despite the crises: Boeing thus plans 82% more planes above our heads by 2041. In parallel with greater individual sobriety and a voluntary reduction in the (many) most unnecessary air journeys, urgent measures must therefore be sought to limit the effects of climate change. aviation on the climate.
This is precisely what Kieran Tait and his team propose in a recently published article in the journal Aerospace – the researcher again sounded the alarm, later, on The Conversation website. According to them, two immediate changes could enable aviation to reduce its climate footprint by 24%.
One of these two changes directly targets the NOx. Kieran Tait thus explains that nitrogen oxides interact, at the high altitudes taken by planes to reduce air resistance, with the atmosphere to burn methane and create ozone.
If the first is a particularly potent greenhouse gasthe second is too, and the balance is unfortunately unfavourable. “Unfortunately, NO emissionsx by airplanes cause more warming through ozone production than cooling through methane reduction. This leads to an effect accounting for 16% of global warming caused by aviation.writes the scientist.
The second change targets contrails, which form more easily in a cold and humid atmosphere and which, by trapping the heat emitted by the Earth’s surface, account for 51% of the total impact of civil aviation.
And as the researcher explains, the difference with CO2 is that NO emissionsx,like the contrails, depend directly on their interactions with the surrounding atmosphere. It is therefore theoretically possible to fly aircraft in conditions that limit the consequences of their non-CO emissions.2and that’s what Kieran Tait offers.
According to the research team, changing the usual routes of aircraft to make them take more optimal paths, avoiding for example the wettest areas and altitudes creating the most lasting and damaging condensation, would be beneficial for the environment despite a slightly higher kerosene consumption.
The shortest path is therefore not necessarily the least polluting: a longer distance of 1% or 2% could, according to some research, reduce the climatic consequences of theft by 20%. But that’s not all: Kieran Tait also puts on the table the idea of flying the planes in formation, rather than alone.
By flying one to two kilometers behind another device, an aircraft could “surf” its suction and reduce CO emissions2 about 5%. Better: the accumulation of nitrogen oxide emissions from the two devices – or more – would make it possible to reach a concentration threshold beyond which ozone is no longer produced.
Contrails, competing for moisture in the atmosphere, would also be limited by these squadron flights. In total, calculates Kieran Tait, the gain if these new rules were applied now for all air traffic could be 24%.
It’s not enough to save the planet, but it’s still a colossal effect, and it’s not the most complex measures to put in place in the very near future.