Is climate change leading to more turbulence on flights?
I never considered myself a nervous flyer until I flew from Chicago's O'Hare International Airport (ORD) en route to Hartsfield-Jackson Atlanta (ATL) for a story with my TPG colleague, aviation reporter Zach Griff, on Feb. 22.
Even though we only had mild rain departing ORD, an ice and heavy rain storm afflicting the Midwest notably influenced my flight, DL 1178, heading south.
About an hour in, it was clear that this would be the roughest flight of my life thus far, so much so that I turned to my seatmate to ask if he was concerned and started sending my last wishes to my loved ones. I even documented the entire saga on Instagram like the millennial journalist I am.
I am not the only one documenting turbulence on recent flights. A passenger on board a Lufthansa flight that was diverted due to "significant turbulence" earlier this month shared what they experienced on social media, per the Associated Press.
While that passenger dealt with clear air turbulence, it turns out my flight experienced what's known as near-cloud turbulence, which develops within a certain range of active weather patterns, such as thunderstorms.
Although I now cover the travel industry, after this frightening experience, I couldn't help but think back to my past life as an environmental reporter.
Is global warming having an impact on flights nowadays? If so, is climate change the sole culprit, and what does that mean long term for aviation? I reached out to a couple of turbulence experts to find out.
Climate change is leading to more turbulent flights year-round
To understand how weather patterns have contributed to more turbulence over the past decade, it's important to know the difference between global warming and climate change. Although the two terms are often used interchangeably, they do not mean the same thing.
Global warming is causing climate change, per Isabel Smith, a third-year Ph.D. student at the University of Reading. Smith is studying aircraft turbulence under Paul D. Williams, an atmospheric science professor and a widely cited turbulence expert.
"The climate is changing because of an increase in greenhouse gases trapping heat that should be emitted out, which is known as global warming," says Smith, who is also a meteorologist.
More specifically, "global warming refers to the rise in global temperatures due mainly to the increasing concentrations of greenhouse gases in the atmosphere," while “climate change refers to the increasing changes in the measures of climate over a long period of time – including precipitation, temperature and wind patterns," according to the United States Geological Survey, a government agency.
When thinking about how weather affects turbulence, we should consider the effects of climate change, reflective of sustained, more intense weather patterns due to global warming. In short, expect more extreme weather as the globe warms.
In the U.S., the only official turbulence documentation on commercial aircraft comes from the National Transportation Safety Board and the Federal Aviation Administration. The latest NTSB data attributed turbulence to nearly 40% of all accidents on large commercial airlines from 2009 to 2018.
NTSB data also cited turbulence for 71% of all inflight weather injuries between 2000 and 2011 globally while noting the most turbulent months are February, July and December.
This research, along with a new report from Smith, relies on high-resolution global climate models that study the four main types of upper-level turbulence: clear air turbulence (also known as non-convective), convectively induced turbulence, near-cloud turbulence and mountain wave turbulence.
"Clear Air Turbulence develops around jet streams, which are fast-flowing bands of wind that propagate around the globe," Smith states in her report examining clear air turbulence trends over the North Atlantic Ocean in high-resolution climate models. "Clear air is projected to increase with climate change because jet streams are strengthening with global warming."
Based on these projections, Smith anticipates that travelers will encounter as much turbulence in the summer months from 1950 to 2050 as previously experienced when flying over the North Atlantic in the winter months during the 1950s.
"All of the seasons are increasing with global warming, in particular, with summer and fall rapidly increasing at similar rates," Smith says. "Spring is increasing at a very irregular rate, and winter remains the most turbulent."
This makes sense given how weather patterns traditionally play out in certain states throughout the year, such as Midwestern winter storms. It also explains why some weather events are occurring more frequently in places you wouldn't expect, such as the recent episode of snow that fell in Southern California.
With the rapid increase in greenhouse gases, heat that should have been emitted into the stratosphere is instead trapped in the troposphere, altering the layer in which we live and where thunderstorms and weather events occur. This affects planes, which ascend and descend after takeoff through the troposphere but often cruise around the barrier between the stratosphere and the troposphere, though the exact position of a plane will depend on the flight route, according to Smith.
"Global warming only refers to global tropospheric warming," Smith says. "This means globally, we have the troposphere warming and the stratosphere cooling at a rapid rate in time. This increases the temperature gradient between the two layers, which strengthens the jet stream, which in turn creates a more unstable wind flow and increases clear air."
In other words, the seasonality of clear air has been altered by climate change, leading to fewer moments of respite from turbulence when flying, according to Smith.
"Winter is typically the most turbulent season over the North Atlantic, but summer and fall periods may increase at a greater rate in time and with global surface warming," Smith's research shows.
The cost of turbulence: Monetary impacts, more delays and longer flights
Scientists, the NTSB and the FAA study the aforementioned types of turbulence impacting aviation.
Clear air is perhaps the most concerning since it develops in cloud-free environments due to the shearing of winds around fast-flowing bands of air (jet streams), making it undetectable to onboard flight radar equipment.
"Aircraft flying at their cruising heights (30–40 thousand feet from the surface) can be struck suddenly from clear air without warning, resulting in damages and injuries," Smith says.
In fact, U.S. airlines spend up to $500 million on turbulence-related injuries, delays and damages annually, according to the National Center for Atmospheric Research.
Beyond a financial concern for airlines, Smith warns travelers of further delays both on the ground and in the air due to turbulence.
"Airlines try to avoid turbulence as much as they can, which often leads to longer flight times and longer wait times," Smith says. As a result, airlines use more fuel and therefore emit more carbon dioxide into the atmosphere.
A 2016 study by one of Smith's Ph.D. supervisors, Paul D. Williams, concluded that this increase in clear air will be costly to the domestic aviation industry.
In a future world with double the amount of CO2 from pre-industrial times, we could expect avoiding clear air will cost the domestic aviation industry $22 million a year. These more convoluted flight routes will lead to the global aviation sector adding an extra 70 million kilograms of CO2 to the atmosphere annually, per the report.
How serious is turbulence?
The latest data from the FAA reports that there were 146 serious injuries because of turbulence on flights from 2009 to 2021.
This research shows that while severe turbulence (which may be fatal) is increasing, you are still more likely to experience light turbulence.
"From light to severe, all severities of clear air are projected to increase in time and with global warming," Smith says. "It's going to be more likely but won't be more severe or fatal."
What can airlines do to curb turbulence?
As one of the biggest emitters of clear air turbulence, the global aviation industry is actively researching the best way to reduce its emissions, Smith says. For example, a 2021 study found that optimizing flight routes could have saved 6.7 million kilograms of CO2 emissions between December 2019 and February 2020.
"However, the most optimal flight route may be the most turbulent," Smith says. "But in terms of what the aviation industry could do to avoid clear air, it's to use these optimal flight routes and clear air forecasting tools to avoid it as much as possible."
Regarding advanced technology to detect clear air, Smith points to studies showing LiDAR as a possible mechanism for detection while juxtaposing others showing it's not cost-effective to implement LiDAR equipment on every aircraft.
Regardless, it would behoove airlines to act quickly to climatize their turbulence technology systems so they accelerate at the same rate at which the world is warming, according to Smith.
Efforts by the Met Office, the national weather service for the United Kingdom, serve as an example of what airlines could do, Smith says. The Met Office has teamed up with Swedish software company Avtech to implement technology to help airlines fly more efficiently via high-resolution models that help determine the most efficient flight routes. This can potentially save 1.24 million tonnes of CO2 each year (or more than 27 million pounds), per the Met Office.
Similar efforts in the U.S. are far less public, Smith says, though the NTSB has advised more stringent rules about seat belt use for passengers and flight attendants when flying in the vicinity of thunderstorms and below 20,000 feet, where 60% of turbulence-related accidents occur, per the aforementioned NTSB report.
However, Smith believes airlines could work more with the National Weather Service to accurately map out clear air turbulence since it's very sudden. Current global onboard models are 75% to 80% accurate but only pick up the presence of turbulence rather than the severity.
Unlike other transportation sectors, such as cars and trains, there's no real way for the aviation industry to stop emissions in the same way that trains and cars can become electric.
"The other sectors are cutting back their emissions already, but aviation cannot act as quickly," Smith says. "The only way for the aviation industry to offset carbon emissions is to make flights more efficient," but that's a tall order, seeing as the aviation sector, in general, indirectly emits a ton of carbon dioxide.
In 2018, global aviation produced 2.4% of total CO2 emissions, according to data from the Environmental and Energy Study Institute, a Washington think tank. As the world’s largest commercial air traffic system, U.S. aviation accounted for 23% of the global CO2 total in 2017.
Still, many airlines recognize that more needs to be done.
United Airlines announced a $5 million investment in algae-based fuel earlier this month, marking the airline's first investment in its recently announced UAV Sustainable Flight Fund, which includes more than $100 million from United and its partners, including Air Canada, Boeing and GE Aerospace.
"This $5 million investment will support the production of sustainable aviation fuel made from algae, an abundant and scalable resource that can be grown and harvested without impacting the food supply chain," United says. Sustainable aviation fuels reduce greenhouse gas emissions, as they serve as an alternative to conventional jet fuel.
United says it has invested in the future production of more than 3 billion gallons of sustainable aviation fuel — the most of any airline in the world. United failed to respond to a request for comment regarding the effectiveness of its investments thus far.
United, like others in the space, including Delta Air Lines, Southwest Airlines and American Airlines, aims to be 100% green by reducing its greenhouse gas emissions 100% by 2050. It aims to do this without relying on traditional carbon offsets.
Beyond the environmental interest in acting quickly, the 2022 Inflation Reduction Act provides a tax credit for using sustainable aviation fuels. Airlines for America, a lobbying group that the above airlines and others are members of, has pledged to make 3 billion gallons of cost-competitive sustainable aviation fuel available to U.S. aircraft operators by 2030.
"Generally, the big airlines are trying to save money as much as possible," Smith says. "More money should be spent on researching better ways to forecast turbulence, which would lead to better ways to plan flight routes to avoid impact rather than creating a delay."
Data suggests that turbulence has increased and is only going to continue to increase on commercial flights.
Though efforts are being made by airlines and weather agencies to implement technology to better forecast turbulence, it can be very difficult to predict given how suddenly it can appear.
Even so, turbulence likely isn't a death sentence, as severe turbulence remains uncommon.
For example, you have just a 3% chance of encountering light turbulence on a flight across the Atlantic from New York to London, according to a 2017 study. In reality, only 1% of the atmosphere has moderately severe turbulence, with just a few tenths of that 1% having severe turbulence, per that report.
While it's true that the likelihood of experiencing turbulence is increasing, it is much more likely to be light turbulence that won't cause any serious injuries.
"The plane isn’t going to fall, but you may just have things falling on or around you," Smith says. "It's always best to stay buckled up and stay seated if it starts to get a bit rocky."