Airlines have managed to cut their carbon emissions by flying their planes at higher altitudes. But that comes at a cost: Higher-flying planes create more and longer-lasting contrails, worsening the industry’s impact on climate change, a new study finds.
“This does not mean that more efficient aircraft are a bad thing – far from it – because they produce fewer carbon emissions per passenger kilometer,” lead researcher Edward Gryspeerdt said in a statement. “However, our results reflect the challenges the aviation industry faces in reducing its impact on the climate.”
Condensation trails (or contrails) are white streaks in the sky behind airplanes. Airplanes create water vapor trails when they fly over humid areas at high altitudes.
An MIT study in March found that contrails account for just over a third of the aviation industry’s contribution to climate change. Contrails trap heat in the atmosphere, which in turn warms the planet.
Private jets, already in high demand under scrutiny for high carbon emissionsrepresent a large part of the contrail problem. Researchers at Imperial College London have found that small aircraft produce contrails of similar size to their larger counterparts.
“We already know that these planes generate a huge amount of carbon emissions per passenger, allowing the super-rich to travel in comfort,” Gryspeerdt said in a statement. “Our findings reinforce concerns about the climate impact of private jets as poor countries continue to be hit by extreme weather events.”
Hope on the horizon?
According to MIT researchers, just a few flights (2% and 10%) are responsible for 80% of contrails. Experts believe that a slight change in the flight path of this small fleet of planes could make a big difference.
American Airlines has already begun experimenting with this technique using the power of artificial intelligence and satellite imagery. In partnership with Google and the company Breakthrough Energy, the airline conducted 70 test flights during which it asked pilots to readjust their altitude. These gradual changes produced fewer contrails.
Dinesh Sanekommu, a product manager at Google, said in an email to CBS News that they are “excited about the impact AI can have on contrail avoidance” and that it has the potential to be a “cost-effective and scalable climate solution.”
This method is not foolproof, however: when planes descend, they burn more fuel. However, environmental correspondent David Schechter said the benefits outweigh the costs. “Google estimates that across an airline’s entire fleet, we’re talking about only 0.3 percent more fuel in exchange for eliminating heat-trapping contrails,” he said.
Another possible solution to the contrail problem, according to scientists at Imperial College London, would be to reduce soot emissions from aircraft engines. This would help to get the white trails out of the sky more quickly, reducing their impact on global warming.
“We have learned from other studies that the number of soot particles in aircraft exhaust plays a key role in the properties of newly formed contrails,” said Marc Stettler, a co-author of the study. “We thought it would also affect the lifespan of contrails.”
