Why Turbulence Is Getting Worse

Singapore Airlines made international news earlier this month when severe turbulence left one person dead and more than 30 injured. Then, just a few days later, a flight attendant broke her back during severe turbulence on a Turkish Airlines flight.

Several other incidents of severe turbulence in the news this weeks suggests that maybe turbulence really has gotten worse. Then again, we’re also living at a time where the airline industry is under a lot more scrutiny, so it’s also possible we’re just hearing about it more because people are already paying attention. A review of recent research, though, shows that’s not the case.

For example, there’s a 2023 paper by University of Reading researcher Mark C. Prosser studied trends in clear-air turbulence, a type of turbulence that occurs without clouds or thunderstorms present, and the results don’t paint a pretty picture. While light-or-greater CAT only increased 17 percent over the North Atlantic between 1979 and 2020, moderate-or-greater CAT increased by 37 percent, and severe-or-greater CAT jumped a whopping 55 percent. So it’s not just that turbulence is happening more frequently. We’re also seeing more severe turbulence.

There’s also a 2017 paper from Dr. Paul D. Williams, a professor of atmospheric science at the University of Reading in the UK who also co-authored the previous study. The paper used a computer model to estimate how much worse turbulence will get when carbon dioxide in the atmosphere doubles. According to the study, we can expect light, moderate and severe turbulence to increase 59, 94 and 149 percent respectively. So expect bad turbulence to only get worse going forward. Those findings are also backed up by another 2023 paper authored by Seoul National University’s Dr. Soo-Hyun Kim, which found that we can expect climate change to make all types of turbulence worse, not just clear-air turbulence.

In a phone interview with Jalopnik, Dr. John A. Knox, an aviation turbulence researcher at the University of Georgia, added additional context:

So there’s definitely the anecdotal situation driven by high-profile events. And then once you have one of those, then the media’s much more likely to jump on the next one. Because then, if there’s another and another, then audiences are primed for that. It seems like a burgeoning trend. But there’s also research that’s been done that I think pretty conclusively demonstrates that we’re seeing more clear-air turbulence especially in the North Atlantic and in the northern hemisphere. So it’s some of both.

Knox also pointed out that in the case of the Singapore Airlines flight, it was likely flying over a thunderstorm, so it experienced a different and more severe type of turbulence than most flights encounter. As he put it, “Clear-air turbulence is high-altitude turbulence away from thunderstorms and usually but not always associated with the jet stream. So if you fly over a thunderstorm, that’s a little different.”

That, of course, raises the question of how exactly climate change makes turbulence worse. According to Knox, part of it can be attributed to warmer water and more humidity in the air. “We’re adding more fuel to the fire for more thunderstorms,” he said. It also creates a stronger temperature gradient in the upper troposphere, the section of the atmosphere below the stratosphere where planes fly. Knox added:

Warmer ocean water and warmer surface temperatures lead to warmer air with more water vapor in it, and that’s the fuel for thunderstorms. So it is entirely plausible that in the future the thunderstorms that we have will be more vigorous than they are now, and it’s already been demonstrated that we’re getting shorter, heavier bursts of rain than we used to in parts of the United States. So if that’s already happening, it seems like a slam dunk for the future. And so if you’re flying around more vigorous thunderstorms or trying to fly above them, it is very plausible that you would have more turbulence related to convection. That could be anywhere obviously, but it’s probably more dominant in the lower latitudes because, quite frankly, we don’t have jet streams as much at the low latitudes.

It’s not just more, stronger thunderstorms, though:

This matters for wind because in the mid-latitudes, that temperature gradient actually drives the wind. It’s a famous relationship in meteorology called the thermal wind law. So ‘thermal’ means temperature and wind means wind. And if you have a strong temperature gradient, going from warm to cold, from the lower latitudes to the higher latitudes, that means in between, in the mid-latitudes, the wind blows stronger, and it blows west to east. As this temperature gradient increases at cruising altitudes, what will happen is that the winds will get stronger. This will lead to more of what we call shear or vertical wind shear, which is the change of a horizontal wind as you go up in altitude. And that leads to turbulence.

So we have an increased temperature gradient in the mid-to-upper troposphere that leads to faster jet streams, and we’ve seen that. There have been reports of planes finding faster, well, not really, but faster than the speed of sound relative to the ground because of the amazing jet stream. So faster winds means more wind shear, which means, at scales that we can’t resolve with computer models, more of a couple things — gravity waves and instabilities. These are small-scale kinds of waves and instabilities that ultimately at the scale of a plane cause bumpiness. In the same way that a wave breaks on the beach, and you see all the foam because of the air in the water, there are waves and instabilities that happen in the atmosphere that lead to the same kind of situation, only you don’t see the foam if there are no clouds. And so you’re flying through a turbulent region without knowing it. And that’s why you have clear-air turbulence.

While it would probably be a stretch to call Knox a doomer, while discussing the future of air travel, he didn’t sound especially optimistic. And yet, he also said we don’t have to accept a future where serious injury and deaths are regular occurrences. After all, planes already have a proven technology for preventing most injuries due to extreme turbulence — seatbelts.

I think globally we will see more turbulence because it’s likely, from the perspective of what’s called convective turbulence or turbulence due to convection — fancy name for thunderstorms — and also, at the same time, in the mid-latitudes because of the changes in the jet stream. So wherever you are, I think it’s likely to be more. Now will this translate to more injuries and death? I hope not because there’s a really simple way to avoid this, which is to be seated with your seatbelt fastened just like they say. The severe injuries happen when people aren’t belted in, either the crew that are doing something and they’re not belted in or passengers who ignore the seatbelt sign and don’t understand why you have the seatbelt sign on in the middle of a flight. Well, this is why.

So I don’t think that it’s a given that we have to have more injuries and certainly not more deaths. We just have to have people realize that they’re not kidding when they say keep your seatbelt fastened. You can ride through a lot with a good seatbelt, but if you’re not belted, and you briefly experience G forces that are circa one or more Gs, then you’re going to hit your head and break your neck. That’s how you can die.

It’s not exactly great news, but at least now you know you’re not imagining things. The turbulence that the Singapore Airlines flight experienced may be a different, less common type of turbulence versus what you usually experience on a plane, but turbulence across the board is worse than it was in previous decades, human-caused climate change is behind it, and it is projected to only get worse. Also, wear your damn seatbelt, people. It’s not that hard, and even if it’s ever so slightly inconvenient, it’s a lot more convenient than having to learn how to walk again because some unexpected turbulence launched you headfirst into the overhead compartment.

This article originally appeared on Jalopnik.