The numbers remain relatively small: there were 207 reported injuries on US commercial flights between 2009 and 2024.
However, high-profile incidents have thrust the issue into the spotlight.
These include an Air Europa flight last year in which 40 passengers were hurt, and a Singapore Airlines flight where one elderly passenger died and dozens were injured.
“Typically injuries [are] to unbelted passengers or cabin crew rather than structural damage,” John Abraham, a mechanical engineering professor at the University of St. Thomas, told AFP.
“Modern aircraft withstand turbulence, so the main risk is occupant injury, not loss of the plane.”
Still, planes must be inspected after “severe” encounters with turbulence – about 1.5 times the normal force of Earth’s gravity – which occur some 5000 times a year over the US, said Robert Sharman, a senior scientist emeritus at the National Centre for Atmospheric Research.
Turbulence also increases fuel consumption when pilots must leave optimal altitudes, alter routes or change speeds, Abraham added.
How climate change is making it worse
Mohamed Foudad, an atmospheric scientist at the University of Reading in the UK, explained there are three main types of turbulence: convective, mountain wave and clear-air turbulence (CAT).
Convective turbulence is linked to rising or sinking air currents from clouds or thunderstorms that can be detected visually or by onboard radar, while mountain wave turbulence occurs over mountain ranges.
CAT, by contrast, is invisible – and therefore the most dangerous.
It generally arises from jet streams: fast-moving westerly winds in the upper atmosphere at the same altitude as commercial jets, about 10-12km up.
With climate change, the tropics are warming faster at cruising altitude than higher latitudes.
That increases the temperature difference between the higher and lower latitudes, driving up jet stream velocity and wind shear – volatile shifts in vertical air currents that trigger CAT.
Foudad and colleagues published a paper last year in the Journal of Geophysical Research: Atmospheres analysing data from 1980 to 2021.
“We find a clear, positive trend – an increase in turbulence frequency over many regions, including the North Atlantic, North America, East Asia, the Middle East and North Africa,” he told AFP, with increases ranging from 60 to 155%.
Further analysis attributed the rising turbulence in certain regions to increased greenhouse gas emissions.
What happens next?
A 2023 paper led by Isabel Smith at the University of Reading found that for every degree Celsius of near-surface warming, winters would bring an increase of about 9% in moderate CAT in the North Atlantic, and summers a rise of 14%.
Winter has historically been the roughest season for turbulence, but warming is now amplifying CAT in summer and autumn, closing the gap.
Jet stream disruption is not the only concern: climate change is also fuelling stronger storms.
“Climate change may also increase the frequency and severity of thunderstorms under future scenarios, and turbulence encounters near thunderstorms are a major component of turbulence accidents,” Sharman told AFP.
In terms of mitigation strategies, Foudad is working on two studies: optimising flight routes to avoid turbulence hotspots and improving forecasting accuracy.
Some airlines are moving towards strategies involving passengers wearing seatbelts more often, such as ending cabin service earlier.
Promising technologies are also being tested, says Sharman, including onboard LiDAR, which beams lasers into the atmosphere to detect subtle shifts in air density and wind speed.
Ultimately, cutting greenhouse gas emissions will be essential, Foudad added.
Aviation is responsible for about 3.5% of human-caused warming.
Airlines are exploring cleaner fuels to help reduce the industry’s footprint, though progress has been “disappointingly slow”, according to the International Air Transport Association.
– Agence France-Presse
