Bumpy flight? Climate change may be to blame for the turbulence

SINGAPORE - Climate change is making the skies bumpier for planes and riskier for passengers, with the warming atmosphere causing more dangerous clear-air turbulence.

A study published on June 9 showed that skies are up to 55 per cent rougher today than four decades ago, increasing costs for the aviation industry.

“Turbulence makes flights bumpy and can occasionally be dangerous,” said Dr Mark Prosser, a meteorologist at the University of Reading who led the study which was published in Geophysical Research Letters.

Turbulence costs the industry between US$150 million (S$201.5 million) and US$500 million a year in the United States, he said. “Every additional minute spent travelling through turbulence increases wear and tear on the aircraft, as well as the risk of injuries to passengers and flight attendants.”

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 per cent from 1979 to 2020, the researchers found.

While the North Atlantic experienced the largest increases, other busy flight routes over the US, Europe, the Middle East and the South Atlantic also saw turbulence rising significantly.

The probability of moderate-or-greater clear-air turbulence was generally larger over oceans than continents and was larger in the mid-latitudes where the atmospheric jet streams are located, the researchers found. A band of moderate-or-greater clear-air turbulence was also evident along equatorial oceans.

Clear-air turbulence can be particularly hazardous because it is hard to detect with the tools now in use in the aviation sector and it can be very localised, making it also hard for weather models to predict. Turbulence caused by storms is easier to pick up on radar and avoid.

The increase in turbulence is consistent with the effects of climate change, according to previous research. Warmer air, caused by greenhouse gases trapping more heat in the atmosphere, is increasing wind shear in jet streams, which are high-altitude belts of wind that are major drivers of global weather. Wind shear refers to vertical or horizontal changes in wind speed and direction. The effects can be hazardous to planes.

To test whether turbulence has risen, Dr Prosser and colleagues analysed 40 years of atmospheric data. They went beyond previous work by calculating clear-air turbulence in 21 different ways for the first time, producing the most detailed picture yet of how turbulence has already started to change.

The researchers found total annual severe clear-air turbulence increased from 17.7 hours in 1979 to 27.4 hours in 2020, or 55 per cent, for an average point over the North Atlantic. Moderate turbulence there rose by 37 per cent from 70 to 96.1 hours annually, and light turbulence increased by 17 per cent from 466.5 to 546.8 hours.

“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,” said Dr Paul Williams, an atmospheric scientist at the University of Reading who co-authored the study.

“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.”