How severe turbulence is linked to climate change

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Back in March, a flight from Austin, Texas to Frankfurt, Germany dropped 1,000 ft after experiencing severe turbulence, resulting in the hospitalization of seven people. An increase of severe turbulence incidents have been reported in the last few years, with several studies linking the reasoning to climate change. 

Turbulence can be defined as air moving in an unprecedented way and is often associated with storms. 

John Ling, president of Canadian Aviation College’s B.C. campus says temperature changes, storms, rain, terrains, and weather patterns lead to extreme turbulence. 

“When the air flows through different temperature areas it causes the air to turn in different directions, some going up, some going down, like water flow,” Ling says. 

Pilots usually avoid flying into turbulence if it’s strong, but sometimes it’s good for them to drive through it for testing, he says. 

Commercial pilots change their flight route in cases of strong turbulence. The weather radar on these flights has the ability to determine the condition of weather from several miles away. Different patterns in weather parameters can lead to strong turbulence. 

“If you fly from Vancouver to Toronto at some point, you will feel the aircraft fly smoothly. When you fly coastal, the mountains and the weather changes and you will feel turbulence and the aircraft shaking,” Ling says.

Terrain turbulence occurs when air moves from one side of a mountain to another side, causing the air to move down towards the mountain. An aircraft that flies into this kind of turbulence will experience a sudden drop. In contrast, turbulence in flat surfaces is caused due to differences in air pressures. An aircraft in this kind of turbulence would experience shaking. 

In order to make turbulence more comfortable and safe, Ling says passengers should always wear their seat belts during the flight. 

The National Transportation Safety Board (NTSB) in the United States found wearing a seat belt can reduce risk of injury, and main aircraft safety risks including inadequate distribution of observations about turbulence, lack of awareness about turbulence risks, and the need for updated guidance about turbulence.

According to the NTSB, more than one third of regularly scheduled air carrier accidents from 2009 to 2018 were turbulence related.  

Ling says he expects the turbulence to get worse as earth continues to warm. 

“More weather disasters are coming because of the climate changing,” he says. “There is lots of pollution which causes damage to the environment, and there’s lots of chemicals used for agriculture.” 

The most dangerous type of turbulence can be classified as clear-air turbulence, which is extremely hard to predict.  

“Flying is a victim of what climate change is about to bring us,” says Kwantlen Polytechnic University environmental instructor Paul Richard. 

Richard recalls being stuck at an airport in New York a few years ago after his flight from Toronto was delayed due to a thunderstorm. Simultaneously, other flights going to Houston or Phoenix had been delayed due to the temperature being extremely hot. 

“We’re talking mostly about clear weather turbulence. When you have clouds and storms, it’s easy to see where the turbulence is. Clear weather [turbulence] is caused by wind shear in the atmosphere, but it doesn’t go along with precipitation [and] formation of clouds. It’s very difficult for pilots to see where that is and that’s why [turbulence] may come as a surprise,” Richard says. 

Moderate or greater clear-air turbulence is predicted to increase significantly in the future due to climate change as vertical wind shears are expected to strengthen at aircraft cruising altitudes, an article on Springer found. 

Another article suggests rising temperatures will affect air transportation in the decades to come. An increase in air temperature results in a decrease in air density, leading to weight restriction and reduced lift generation on the aircraft. Airports at a high elevation or with short runways and high temperatures are expected to experience the largest impact during takeoff. The study recommends remodelling aircraft design, airline schedules, and runway lengths. 

A research letter published by Advancing Earth and Space Science found severe clear-air turbulence is expected to double over in North America, the North Pacific, and Europe. It is also predicted to become more common over the North Atlantic region by 2050 to 2080. 

The letter found strong, vertical wind shear, airflow in mountainous terrain, and a loss of balance as the main factors behind clear-air turbulence. It recommends improving clear-air turbulence forecasts to result in effective flight planning along with limited discomfort and injuries for passengers and crew. 

Richard says climate change is reducing the degree of wind shear in the atmosphere, according to some scientific publications. 

“It’s basically weakening the boundaries between masses of cold air and masses of warm air,” Richard says. 

“What vertical wind shear in that case means is you have winds going in one direction at a certain elevation [and] in another direction at a lower elevation.”

More wind shear is found where the jet stream occurs. He says the polar jet stream, which is created by cold air masses from the Arctic and warm air from the tropics, now wanders off and brings cold air into unusual places.

While the wind speed in the polar jet stream has not changed much since 1979, satellite observations show there has been a 15 per cent increase in vertical wind shear. This increase is also in correspondence with clear-air turbulence experienced on flights, according to an article by Nature. 

The article found the upper-level jet stream is strengthening in the upper atmosphere due to human-induced climate change, and as a result weakens the lower atmosphere. This discrepancy at different altitudes has resulted in a balanced tug-of-war. 

According to an article from The Guardian, there are signs the North Atlantic jet stream is shifting northward.

“So short of controlling climate change by itself and reducing the degree to which the Arctic is warming, there’s not a lot that can be done,” Richard says. 

A report from the NTSB recommends improving weather forecasting, distribution of weather reports, and management of air traffic to reduce turbulence-related accidents. They also recommend a forecasting product called “turbulence nowcast” to provide pilots, dispatchers, and air traffic controllers with accurate information to respond to turbulence efficiently.

Aside from the increase in greenhouse gases like carbon dioxide and methane, Richard says the atmosphere itself is not changing much due to climate change, but more so its dynamics. 

He says it is difficult to predict weather now due to the mixing of air zones in the atmosphere. This can also be attributed to a decrease in the temperature difference between the poles and the equator.

Turbulence can be characterized as mild, moderate, severe, and extreme, with the aircraft being momentarily and completely out of control in severe and extreme turbulence respectively. 

Paul Harris, manager of flight operations at the Pacific Flying Club, says the intensity of updraft and downdraft, which is proportional to the intensity of the airspeed, determines the intensity of turbulence.

“The greater the distance, the greater speed difference, the greater the turbulence,” Harris says. 

“[For example,] in a room, there is still air, so there’d be no turbulence. However, if you have a stove on, you’d see the [hot] air rising above the stove, and if you flew an airplane through that rising air, the airplane would bounce around and that would be turbulence,” Harris says. 

He says aircrafts experience turbulence as they transition from one part of the air mass to another. In case of extreme turbulence, the pilots follow a protocol by slowing the airplane down and flying it into an area with less turbulence. 

“Turbulence is a product of weather; climate is a long-term change. Climate change creates a potential for more severe weather, but it doesn’t guarantee more severe weather,” Harris says. 

Richard says as the world becomes more aware of climate change, there are going to be efforts to reduce airplane pollution. At the same time, Richard says these efforts will make flying less convenient for the public, possibly leaving an impact on tourism and resulting in an increase in online communication for work.  

He hopes to see measures put in place to reduce the impact of climate change on the future of flying. 

“Some of these measures … [have] to do with things as simple as, ‘At what elevations do airplanes fly? How much fuel are they burning? And what kind of fuel are they burning?’ It’s not the full [solution], but it’s part of it,” he says. 

“The other part of it may be that there’s more taxes on fuel, and that tax goes into measures to help fight the impacts of climate change,” Richard says.