There have been many recent instances of sudden and severe turbulence on flights that has caused serious injuries and even a death in one case. Korean Air has decided to stop serving instant ramen on flights because of the burn danger posed by worsening turbulence. A new study has indicated that a difficult-to-forecast type of air turbulence will likely become more common in the Northern hemisphere because of the ongoing impacts of climate change. This study, which was reported in the Journal of Geophysical Research: Atmospheres, also determined that turbulence in the Northern hemisphere also increased between 1980 and 2021. They research focused on so-called clear air turbulence, which can be difficult to predict and tends to strike aircraft unexpectedly.
This study is a follow-up on previous research that used data and computational tools to predict increases in moderate or severe air turbulence. Turbulence is likely to increase in areas that are impacted by the jet stream, a region of rapidly moving West-to-East air currents about ten to twelve kilometers (~32,000 to 39,000 feet) above the Earth’s surface, which is also where commercial planes usually fly. As the climate continues to warm, air turbulence there will continue to increase.
Turbulence is usually expected when aircraft are flying over mountain ranges or through thunderstorms. The activity or movement of wind near mountains can create unstable air, and swirls or eddies that generate turbulence. But there is no reliable way to detect and avoid clear air turbulence. The researchers are cautioning aviation engineers to account for the increase in clear turbulence in future aircraft designs.
“We know that clear air turbulence is the main cause of aviation turbulence, which causes approximately 70 percent of all weather-related accidents over the United States,” said lead study author Mohamed Foudad, an atmospheric scientist at the University of Reading. “We now have high confidence that climate change is increasing clear air turbulence in some regions.”
Right now, this study has indicated that most clear turbulence happens near jet streams. Planes that fly through jet streams are sometimes struck by rapid updrafts known as vertical wind shear, which are like clear air turbulence.
The speed of the jet stream and the frequency of vertical wind shear are both expected to increase as the climate warms, because that increases the energy level in the atmosphere.
Clear air turbulence now impacts planes about 1 percent of the time in the Northern Hemisphere, but it is expected to also become more common. It's now most frequent over East Asia, and moderate or severe clear turbulence affects planes in the area about 7.5 percent of the time, since the subtropical jet stream in the atmosphere there is strongest.
The 1980 to 2021 dataset indicated that moderate-to-severe clear turbulence has increased by about 60 to 155 percent over East Asia, the Middle East, North Africa, the North Atlantic, and North Pacific.
“We will see more of these accidents, but people should also be aware that aircraft are designed to resist the worst turbulence that could happen,” Foudad said.
Sources: AGU, French National Centre for Scientific Research (CNRS), JGR Atmospheres