Why modifying 3% of air routes can be so beneficial for the climate

Commercial aviation generates approximately between 2.5 and 3% of global CO emissions₂. Of this 3%, 81% corresponds to the passenger flights and the rest to those of cargo. In addition, there are other harmful effects, the so-called “non-CO emissions₂“, such as those produced by condensation trails, which are artificial clouds of condensed water vapor that can form and persist for a long time when airplanes pass by and that, in addition to water vapor, contain carbon dioxide, nitrogen oxides , carbon monoxide, hydrocarbons such as methane, sulfates and combustion particles In this case, explains an analysis by the European association of. Transportation and Environment (TEA), It would be enough to modify the routes of a tiny proportion of flights (3%) to reduce by more than 50% the effect of contrails on the climate.

A small effort, a big change

The new report from the main European independent organization for the decarbonisation of transport explains that the additional fuel used to “lengthen” routes and thus avoid contrails would correspond to an increase of just 0.5% in consumption, on an annual basis , of all world civil aviation. Individual flights whose routes would be modified, for a fuel increase of around 5%they could reduce the climate-disrupting effect of contrails by 80%.

And no, the minimum increase in fuel necessary would not make the effort in vain. According to T&E’s analysis, preventing contrail formation is, in fact, a “no regrets” strategy: the net climate effect is always positive“since the benefits of avoiding the formation of contrails are always greater (between 15 and 40 times) than the impacts of additional CO emissions₂ generated by the change in flight paths,” reads a note from the organization. Benefits that could increase with the improvement of observation technology (satellites and ground cameras), weather forecasting and humidity sensors.

Among other things, in the scenario proposed by the organization a series of very conservative assumptions were made, which result in an estimated cost of the no condensation trail formation between 3 and 10 times higher than other scientific sources, with fewer associated climate benefits. Under less conservative but plausible assumptions, the costs would be lower and the climate benefits greater, making the contrail avoidance strategy even more attractive.

The impact

The entire argument revolves around the fact that geography and flight latitude greatly influence the climate impact of contrails. The flights over North America, Europe and the region from the Atlantic North, for example, accounted for more than half of the global warming from contrails in 2019. Flight hours They also contribute to climatic effects: those formed by evening and night flights have the greatest impact. The same applies to seasonality: contrails with the most pronounced effect tend to form in winter.

“The aviation industry is being offered a simple and highly cost-effective way to reduce its impact on the climate,” he explains. Carlo Trittoresponsible for Sustainable Fuels at T&E Italia. “Some operators in the sector tend to ignore the problem of contrails, but the climate benefits associated with not forming them are enormous, and the solutions to mitigate the phenomenon are improving day by day.” If we identify and modify the trajectories of those few flights that cause the most contrails condensationwe can have an immediate effect on the climate impact of aviation. “It is no longer time to discuss whether it is necessary to do it, but how to do it.”

The costs

In fact, containing contrails would not cost much. The study indicates that diverting trajectory of an intercontinental flight from Rome to Montreal, to reduce contrails and using a conservative estimate, it would cost only 2.09 euros (2.21 dollars) per ticket (and less than 1 euro (less than 1.06 dollars) for an intra-European flight like Milan-Stockholm). An estimate that takes into account both the costs of the increase in fuel required and those of all the technologies necessary to avoid contrails (humidity sensors, satellites and other instruments). For every ton of CO₂ Reduced equivalent, this strategy is more than 15 times cheaper than other climate solutions such as carbon capture and storage, which are still in a very slow testing phase. In short, a cheap, easy and available solution for the aviation industry to limit its impact.

airlines, startups and other companies are already launching projects of this type. In 2023, a proof on 70 flights, in which the formation of condensation trails was avoided by 54%, with a penalty (in terms of fuel consumption) estimated at 2% for the airlines that participated in the test. However, to ensure that contrail formation is avoided on a large scale, vigilance is required. In fact, the organization recommends that keep track of all flights departing and arriving in the Union from 2027and that regulatory authorities begin to set standards for contrails in European airspace. We also need more research on the topic and incentives for those who first decide to adopt these strategies, changing routes in a virtuous way.

“There are few climate solutions that can be implemented so quickly, at such low cost and with minimal impact on industry and consumers. We call on policymakers and the aviation industry to act now, side by side, to ensure that In 10 years our skies will be free of contrails. This is the opportunity of the decade to reduce the climate impact of aviationso we have to act now,” concludes Tritto.