00:56 - Source: CNN
The most dangerous type of turbulence

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With climate change, you can expect a bumpy ride, scientist says

"Severe turbulence" expected to increase by 149%

CNN  — 

Climate change is expected to affect your life in some surprising ways in the coming decades. From worsening pollen allergies to lowered sex drives, raising the planet’s temperature by continued greenhouse gas emissions has wide ranging impacts – but did you know that global warming may also make your plane ride significantly bumpier?

There is a growing amount of research that shows that as the planet warms from climate change, the second half of this century will see an increase in turbulence, especially along the heavily-traveled transatlantic routes in the Northern Hemisphere (like routes between Europe and North America).

“Climate change is strengthening the north-south temperature difference that drives the jet stream,” according to Dr. Paul Williams of the University of Reading in the UK.

“A stronger jet stream is less stable and means more clear-air turbulence,” Williams told CNN.

Clear-air turbulence is the most common cause of your in-flight roller coaster, and can result in significant injuries, such as earlier this week on a Aeroflot flight from Moscow to Bangkok, Thailand.

Williams and his colleagues most recent research, published last month in the journal Advances in Atmospheric Sciences showed that turbulence of all severities increases in model simulations of a warming climate – but the largest increase is seen in “severe turbulence” – the kind that hit the Aeroflot flight.

“Increases in light and moderate turbulence will not injure anyone, but they will cause anxiety amongst nervous fliers.” Williams said.

At least 27 passengers were injured when an Aeroflot flight from Moscow to Bangkok hit severe air.

“On the other hand, the 149% increase in severe turbulence that we have calculated does have the potential to cause more serious injuries.”

Clear-air turbulence (CAT) is caused by rapid changes in speed or direction of air movement.

This occurs most commonly in and around an invisible current of rapidly moving air called the jet stream, which can be found at a height similar to where commercial planes fly, around 30,000-40,000 feet above the ground.

This map shows upper level winds around flight level. The jet stream refers to the belt of strongest winds, indicated by the brighter orage and red colors on the map. Obtained from Weatherbell.com.

The jet stream generally follows the boundary between hot and cold air, and is strongest when the difference between the hot and cool sides is the strongest, which occurs during the winter months.

The idea behind the climate change and turbulence link is fairly straightforward. If climate change influences the intensity and position of the jet stream, the turbulence resulting from that jet stream would be impacted.

Human-produced emissions contribute heavily to climate change. There may be a bit of high-level irony here: The aviation industry is a significant emitter of carbon dioxide and other greenhouse gases.

Williams said there’s evidence the rate of turbulence injuries has risen significantly since the 1980s, even after correcting the statistics to account for the growth in aviation, but he stopped short of saying that it is caused by the warming we have already seen.

“We need to interpret this evidence more carefully,” Williams said.

According to current projections, future changes in the jet stream will cause significant disruption to aviation.

“The consensus of the climate models is that global climate change will cause the [average] position of the jet stream to shift closer to the poles in both hemispheres,” according to Dr. Jason Furtado, an assistant professor of meteorology at the University of Oklahoma.

Furtado, who researches how climate change will influence the upper levels of the atmosphere, said, “The strength of the jet stream is also anticipated to increase, as the temperature change with latitude in the upper troposphere [which is where planes fly] increases in the future.”

This would be a double whammy to aviation.

An increase in the speed of the jet stream would increase the turbulence in and around it, meaning more incidences of aircraft hitting these pockets of severe clear-air turbulence.

Potentially more concerning would be the movement of the jet stream closer to the poles. In the Northern Hemisphere, this would mean a shift to the north, putting the jet stream right in the path of the “North Atlantic Tracks,” a sort of highway in the sky that marks the frequently traveled routes across the Atlantic between Europe and North America.

Not only would climate change make the turbulence more frequent and intense, it would cause it to potentially impact thousands of more flights a day, based on current routing.

And there’s this: Increased turbulence would likely mean airliners will try to avoid certain areas, resulting in added fuel and other costs. A stronger jet stream might make trips from Europe to North America longer and more expensive (more fuel needed). On the flip side, the reverse route would be faster and cheaper.

While Williams’ studies have focused on the transatlantic routes in the Northern Hemisphere, he feels the impacts will be felt globally.

“I would expect the same conclusions we have reached about the North Atlantic to apply to other mid-latitude flight routes around the world (in both northern and southern hemispheres). We are currently crunching the numbers for these routes,” Williams told CNN.

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    But don’t cancel your post-2050 flight travels just yet, according to Furtado, “there are some questions as to the robustness of the poleward/strengthening jet stream findings” in some of the latest climate model runs.

    Furtado told CNN “the conclusion of a poleward and strengthening jet stream might vary regionally and seasonally,” and is “something climate scientists need to study and understand further.”

    CNN’s Judson Jones contributed to this story.