LEILA FADEL, HOST:
If you sometimes forget to fasten your airplane seat belt, you might want to think twice. Severe turbulence on a Singapore Airlines flight killed one passenger yesterday and injured dozens more. Photos showed dents in the plane's overhead compartments and overhead cabin panels dangling from the ceiling. Turns out turbulence is on the rise, due at least in part to climate change. That's according to a study authored by Paul Williams, a professor of atmospheric science at the University of Reading in the United Kingdom. Good morning, and thanks for being on the program.
PAUL WILLIAMS: Good morning, Leila. It's a pleasure.
FADEL: So most people who fly have been on these bumpy flights where planes shake and make sudden short drops, which always makes my stomach drop. Would you start by explaining what exactly causes a plane to shake so much mid-flight?
WILLIAMS: Well, there are different kinds of turbulence in the atmosphere that can do that. Of course, flying through a storm is always going to be unpleasant, but there are more subtle forms of turbulence, too. In fact, it turns out flying over a mountain range like the Rockies, for example, is usually turbulent, too, and then, in fact, there's a third kind of turbulence called clear air turbulence that's completely invisible, has nothing to do with storms and is generated by these fast currents in the atmosphere called jet streams.
FADEL: And your study found that climate change is making turbulence worse?
WILLIAMS: Yes. This started out as a theory about 10 years ago. We ran some atmospheric model simulations of the future, and we found that severe turbulence was doubling or trebling. And then more recently, we've actually analyzed historic data, going back to when satellites first began, observing the jet stream in 1979, and we found out that there today is 55% more severe clear air turbulence than there was back in the 1970s, so clearly, there's already been an increase, and we expect much more of an increase in the future, as well.
FADEL: Now, typically, when a plane is about to go through turbulence, the captain will say - you know, the fasten seat belt sign goes on, people put their seat belts on, but how effective are airplane systems at detecting the type of turbulence that climate change is increasing?
WILLIAMS: Well, of course, there is a radar, a weather radar in the flight deck that is excellent at visualizing turbulence related to storms, so in theory, at least, it should be always possible to fly around storms rather than into them - but this clear air turbulence does not get picked up by the radar.
FADEL: Oh.
WILLIAMS: It's completely invisible, and often there's just no prior warning - it comes literally out of the blue.
FADEL: So should people just wear their seat belts all the time? I mean, 'cause I think the shocking thing about the Singapore thing is how much damage the plane - was on the inside of the plane just from turbulence.
WILLIAMS: Absolutely. It must have been horrifying. I think for the people onboard who were not seat-belted - because, as I understand it, the seat belt line was not on at the time - this must have been like being on a roller coaster without any restraints in place.
FADEL: Oh, my gosh.
WILLIAMS: The turbulence would have been severe, and that means that you could lift up out of your seat. In other words, even gravity is not strong enough to keep you pinned to your seat. Really, keeping your seat belt fastened - this is personally what I do whenever I fly, even if the seat belt light is switched off, unless I'm going to the restroom, I'm in my seat, and my seat belt is firmly attached.
FADEL: OK, well, I will be doing the same thing from now on. Paul Williams, professor of atmospheric science at the University of Reading, thank you so much for your time.
WILLIAMS: My pleasure. Thank you.
(SOUNDBITE OF CIRCLES AROUND THE SUN'S "GILBERT'S GROOVE") Transcript provided by NPR, Copyright NPR.
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