Aviation turbulence has increased by 55% as the world warms

Ryanair Boeing 737-800 turbulent landing,
Source – Ronnie Macdonald from Chelmsford and Largs, United Kingdom. CC SA 2.0.

Clear-air turbulence (CAT), which is invisible and hazardous to aircraft, has increased in various regions worldwide.

Whether you’re a frequent flyer or just an occasional air traveler, you know how unpleasant hitting turbulence can be. Besides being just plain scary, strong turbulence can even cause injuries.

A team of scientists from the University of Reading says our new study, published in the journal Geophysical Research Letters on June 8, 2023, shows that clear-air turbulence (CAT), which is invisible and hazardous to aircraft, has increased in various regions worldwide.

Over the course of the past four decades, the researchers found that severe turbulence has increased on many busy flight routes around the world, including in Europe, the US, and the North Atlantic.

At a typical point over the North Atlantic — one of the world’s busiest flight routes — the total annual duration of severe turbulence increased by 55 percent from 17.7 hours in 1979 to 27.4 hours in 2020, the research found, according to Live Science.

Moderate turbulence increased by 37 percent from 70.0 to 96.1 hours, and light turbulence increased by 17 percent from 466.5 to 546.8 hours.

Ph.D. researcher Mark Prosser said: “Turbulence makes flights bumpy and can occasionally be dangerous. Airlines will need to start thinking about how they will manage the increased turbulence, as it costs the industry $150-500 million annually in the USA alone. Every additional minute spent traveling through turbulence increases wear-and-tear on the aircraft, as well as the risk of injuries to passengers and flight attendants.”

Professor Paul Williams, an atmospheric scientist at the University of Reading who co-authored the study, said: “Following a decade of research showing that climate change will increase clear-air turbulence in the future, we now have evidence suggesting that the increase has already begun. We should be investing in improved turbulence forecasting and detection systems, to prevent the rougher air from translating into bumpier flights in the coming decades.”

Approaching Washington Dulles International Airport, late at night. Source – Famartin (CC BY-SA 4.0)

Turbulence and climate change – What’s going on?

CAT is now defined as aircraft turbulence that occurs at altitudes of around 7,000–12,000 meters (23,000–39,000 ft) as it meets the troposphere, either in cloud-free conditions or within stratiform clouds.

Clouds have nothing to do with CAT – instead, CAT is generated by wind shear (wind variations with altitude), which is concentrated largely in the jet streams, according to The Conversation.

Data from studies of the wind shear in Jet Streams shows it has increased by 15 percent at aircraft cruising altitudes since satellites began observing it in 1979. A further increase of around 17 to 29 percent is projected by 2100.

The CAT is an expected part of the effects of climate change. Atmospheric feedback loops are at work, or in other words – warming generates further warming. It is a vicious cycle and is only expected to get worse.

So, it goes without saying that every additional 1°C of global warming will increase the amount of turbulence further still.

Aviation turbulence has increased by 55% as the world warms
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