Airplane contrails, the white streaks one sees in the skies, have often been accused by conspiracy theorists of being a government project to manipulate the weather. Though this has been debunked by scientists, the fact that contrails affect the climate is well-known. Now, a new study warns that the heating effect of the contrails will triple by 2050.
Negative climate effect
Airplanes negatively affect the climate in two ways — through the greenhouse gases that are released when they burn fuel, and through the heat-trapping effect of their contrails. These contrails can last for up to half a day. In some cases, they can merge with the clouds and spread across thousands of square miles, widening the heat-trapping effect.
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“Given the increasing rate of air traffic we see now, there’s not much we can do to keep the climate impact constant… Usually people say clouds are cooling the surface. For lower clouds that’s true. They reflect sunlight. But high clouds that are optically thin are most likely to warm the atmosphere,” Ulrike Burkhardt, a co-author of the study, said to Inside Climate News.
The effect of contrail cirrus clouds is expected to be much greater in regions like Europe and North America, since they have some of the busiest air traffic routes in the world. But as Asia grows economically, the situation in the region is also expected to worsen. Last year, transportation was found to be the biggest source of greenhouse gas emissions in the U.S. for the third time in a row. Emissions from airplanes are rising at a much faster rate than cars, since the latter have seen vast improvements in fuel efficiency.
However, not everyone is alarmed by the report. “The ‘radiative forcing’ (RF) of contrail cirrus is indeed several times larger than that of CO2 from aviation but comparing the RF of a short-lived climate effect to that of a long-lived greenhouse gas is fraught with difficulties as the effect of CO2 last many thousands of years because of its long lifetime; the warming effect of contrail-cirrus would be a few decades at most,” David Lee, Professor of Atmospheric Science, Manchester Metropolitan University, said to Science Media Center.
The International Air Transport Association (IATA), which represents about 290 airlines accounting for 82 percent of total global air traffic, has announced that it will cut greenhouse emissions by 50 percent by 2050. However, it does not state how they plan on managing the warming caused by contrails.
“The industry’s short-term plan is to increase fuel efficiency by replacing older aircraft with newer ones. Airlines are also calling for governments to adopt a voluntary offsetting scheme that would become mandatory after 2027. Called the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), it would cap net emissions from international aviation at 2020 levels. To stay below the cap as air traffic continues to grow, airlines could purchase offsets through a carbon market,” according to Bulletin Of The Atomic Scientists.
Even though there are plans to reroute air traffic in order to safeguard regions most sensitive to the negative effects of contrails, some experts worry that such actions could end up increasing emissions of greenhouse gases that would last longer and do more damage to the climate. In the U.S., the Environmental Protection Agency (EPA) is reportedly developing new rules to minimize the climate effects of air travel.