Just hours ago on Wednesday, July 31, a Delta Air flight had to make an emergency landing after being hit with severe turbulence, leaving at least 25 passengers injured.
Reports of flight turbulence aren’t uncommon, but they have become more frequent and severe over the past few years.
Death as a consequence of turbulence is also extremely rare. According to BBC News, there are no official figures on deaths caused due to turbulence, but it is estimated to have been roughly four deaths since 1981.
Injuries, however, tell a different story. Passengers caught in incidents of severe turbulence often end up with bruises, gashes and broken bones. If they’re lucky, it is all they endure.
Of the severe injuries caused to passengers flying throughout 2023, almost 40% were caused by turbulence, according to the annual safety report by the International Civil Aviation Organization.
In the US alone, there have been 207 severe injuries – where an individual has been admitted to hospital for more than 48 hours – since 2009, BBC News reported, citing official figures from the National Transportation Safety Board show. Of these, 166 were crew and may not have been seated.
But why are flight turbulence incidents more frequent now?
According to BBC News, citing experts, air travel could become bumpier as climate change shifts atmospheric conditions; temperature changes and shifting wind patterns in the upper atmosphere are expected to increase the frequency and intensity of severe turbulence.
“We can expect a doubling or tripling in the amount of severe turbulence around the world in the next few decades,” Professor Paul Williams, an atmospheric scientist at the University of Reading, told the publication.
“For every 10 minutes of severe turbulence experienced now, that could increase to 20 or 30 minutes,” he added.
3 key causes of turbulence:
- Convective: Clouds or thunderstorms
- Orographic: Air flow around mountainous areas
- Clear-air: Changes in wind direction or speed
While each type could bring severe turbulence, convective and orographic are often more avoidable; it is the clear-air turbulence that cannot be seen and seemingly comes out of nowhere.
Climate change drives turbulence
Climate change is a major factor in driving up both convective and clear-air turbulence.
Convective turbulence
Climate change and thunderstorms have a complex relationship; a warmer atmosphere can hold more moisture, and that extra heat and moisture combine to make more intense thunderstorms.
Convective turbulence is created by the physical process of air rising and falling in the atmosphere, specifically within clouds. And there are never more violent up and down drafts than in cumulonimbus or thunderstorm clouds.
One US study, published in the Science journal in 2014, showed that for a 1 °C increase in global temperature, lightning strikes increase by 12%.
Clear-air turbulence
The BBC News report said clear-air turbulence is caused by disturbed air in and around the jet stream. Wind speeds in the jet stream travelling from west to east across the Atlantic can vary from 160mph to 250mph.
There is colder air to the north and warmer air to the south. This temperature difference and change in winds are useful for airliners as a tailwind to save time and fuel. But it also creates turbulent air.
“Climate change is warming the air to the south of the jet stream more than the air to the north so that temperature difference is being made stronger,” explains Prof Williams. “Which in turn is driving a stronger jet stream.”