When the plane drops, many travelers' hearts drop. Turbulence is not only an unpleasant part of air travel for people who are afraid of flying. When schoolchildren fly on vacation this summer, they are more likely to be rocked by turbulence than those who took a plane a few decades ago. This is shown by a study by the British University of Reading. The scientists attribute the "turbulence change" to climate change.
The study, published at the beginning of June, focuses on clear air turbulence, which does not occur in a foreseeable manner on mountain ranges or during storms, but captures the aviator in free flight "out of the blue". A key result: This turbulence increased in the period under study from 1979 to 2020. The increase was particularly strong in the middle latitudes and especially over the USA and the North Atlantic. The total duration of severe turbulence over the North Atlantic increased by 55 percent, according to the study. Medium turbulence occurred 37 percent longer, and light turbulence 17 percent longer. But other regions are also affected, such as routes across Europe.
Turbulence - popularly also called "air pockets" - is caused by gusts that move from top to bottom or from bottom to top. They change the flow on the wings and thus the lift: the plane sags or pulls up suddenly. The authors had already established a connection between the increase in turbulence and climate change in earlier studies. Study co-author Paul Williams explains that at cruising altitude, climate change will warm the area south of the jet stream more than the area north of it. The larger temperature difference leads to stronger wind shears - i.e. sharp changes in wind direction - and thus to more turbulence.
And according to the forecasts, they should continue to increase in the future as climate change progresses. "If we use supercomputers to simulate a future in which the amount of CO2 in the atmosphere is twice as high as in the pre-industrial era, then we see about twice or even three times as much severe clear-air turbulence," explains Williams. "Any additional amount of CO2 in the atmosphere means more temperature difference in the jet stream, which means more wind shear, which in turn means more clear air turbulence."
Turbulence is uncomfortable for passengers, but even more so for the crew, who have to go through the cabin during this time, emphasizes Patrick Vrancken from the German Aerospace Center (DLR) in Cologne. They also meant stress for the pilots. In severe turbulence there is a risk of injury. At the beginning of March, a total of 27 people were injured on board two Lufthansa and Condor planes. After all: "Structurally, aircraft have been built sufficiently strong for decades," says Vrancken. "Even an increase in turbulence intensity by a few percent would not change this."
According to the study authors, turbulence costs the industry between $150 million and $500 million annually in the US alone. The costs arise from additional fatigue in the aircraft cabin, maintenance work, occasional damage to the aircraft or the treatment of crew and passenger injuries. Turbulence also causes even more emissions - and air travel already contributes significantly to the climate crisis. It's not just about carbon emissions. According to the Federal Environment Agency, the nitrogen oxides, aerosols and water vapor produced at high altitudes when kerosene is burned also contribute to warming of the atmosphere. Flying is therefore the most climate-damaging way of moving around.
According to Patrick Vrancken from DLR, the aviation industry has been reacting to the increasing turbulence for many years. Above all, work is being done to improve the forecast. Researchers at DLR are working on a method that will detect turbulence a few hundred meters in advance and allow the on-board computer to take countermeasures automatically.