As airplanes can leave behind a lot of carbon emissions during flight, air traffic is a significant contributor to air pollution. This is not at all surprising considering that there are 4 billion passenger boardings each year, which entailed over 35 million flights in 2017, according to IATA. This amounts to more than a hundred thousand flights each day of the year.
The environmental impact of this heavy air traffic is staggering. About 39 million commercial flights in 2018 generated over 900 million metric tons of CO2.
These astounding numbers indicate that commercial aircraft release almost a billion tonnes of carbon dioxide in the atmosphere each year. Therefore, drastic measures need to be taken to curb the relentless pollution of the skies, which can jeopardize the environment and our health and well-being.
The good news is that small changes can have a significant impact on air traffic pollution levels. According to a research study published by the Imperial College of London, a flight altitude change of as little as 2,000 feet can lead to a dramatic reduction in air traffic pollution.
The researchers are saying that these flight changes, with the latest environmentally- friendly aircraft engines, can lead to a 90 percent drop in air pollution. The lead researcher of the paper said that the results of their studies show that small changes in aircraft altitude can drastically bring down the adverse environmental impact of commercial aviation.
An aircraft leave behind long trails of exhaust on which moisture condenses. Hence, these are called contrails. It is not unusual to find long contrails crisscrossing each other in the sky at any given point in time. These contrails can last for as much as 18 hours.
Researchers deployed computer simulations to find out the effects that altitude changes can have on these environmentally-disastrous contrails. The researchers worked on data derived from Japanese airspace. Here, they found a key statistic: just two percent of flights were responsible for 80 percent of the radiative forcing. Radiative forcing refers to the climate impact that contrails generate. A small percentage of flights are responsible for much of the contrails that we witness in the sky.
Radiative forcing from contrails is different from the climatic impact of carbon emissions. It comes to an end as soon as the contrail dissipates, whereas the same cannot be said for carbon emissions. Hence, reducing contrails can drive down radiation forcing.
When researchers carried out flight simulations at 2000 feet above and below the actual flight paths of just 1.7% of the total flights, they observed a 59 percent reduction in the overall radiative forcing.
The results of this study are quite encouraging. They prove that small changes in flight paths for a tiny fraction of all the flights can lead to a dramatic drop in contrail climate forcing.