Fasten your seatbelts: Is air turbulence becoming more common due to the climate crisis?

Singapore Airlines flight SQ321 experienced severe turbulence over the Indian Ocean on Tuesday (21 May) which resulted in one death, with officials reported numerous injuries among the passengers, some of which were severe.

An airport official suggested that the 73-year-old British man may have suffered a heart attack, although this has not been confirmed. The Boeing 777, carrying 211 passengers and 18 crew members, was en route from London’s Heathrow airport to Singapore when the incident occurred. Due to the turbulence, the aircraft was diverted and made an emergency landing in Bangkok amidst stormy weather conditions.

What is clear-air turbulence?

Turbulence refers to unstable air that moves unpredictably and in a chaotic manner.

It is categorised as light, moderate, severe, or extreme. While the first two can be alarming to some passengers, only the latter two pose significant danger, particularly to those who are not securely fastened.

Though turbulence is often associated with heavy storms, the most perilous type is clear-air turbulence (CAT). This wind-shear phenomenon can occur in wispy cirrus clouds or even clear air near thunderstorms, where differences in temperature and pressure generate powerful air currents.

CAT frequently occurs in or near high-altitude jet streams. Wind shears occur when two large air masses move at different speeds. Planes can encounter clear-air turbulence without warning.

Is climate change making air turbulence worse?

One study at UK’s Reading University found that higher temperatures resulting from the climate crisis are causing significant increases in turbulence across transatlantic flights.

The June 2023 study analysed modern atmospheric data from four decades of observations (1979–2020) to investigate whether clear-air turbulence (CAT) had already started to increase. Using 21 different turbulence calculations to ensure reliability, the study found clear evidence of significant increases in CAT at aircraft cruising altitudes in various locations worldwide since satellite observations began.

The study revealed that 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 17.7 hours in 1979 to 27.4 hours in 2020, the research found. Moderate turbulence increased by 37 per cent from 70.0 to 96.1 hours, and light turbulence increased by 17 per cent from 466.5 to 546.8 hours.  

The study also stated that “at a typical point over the North Atlantic, the upward trend is such that the strongest category of CAT was 55 per cent more frequent in 2020 than 1979.”

Prof. Paul Williams, one of the study’s authors, stated at the time that the predicted choppier skies have already arrived.

“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," Williams had said.

Also Read: Can pilots avoid in-flight turbulence?

While the US and North Atlantic have experienced the most significant increases, the study also found that other busy flight routes over Europe, the Middle East, and the South Atlantic have seen substantial rises in turbulence.

How rare is a death due to CAT?

“The last fatality caused by clear-air turbulence on a commercial flight occurred on 28 December 1997, on a United Airlines flight from Tokyo to Honolulu,” stated Williams in a statement on Tuesday, reiterating that there was “strong evidence that turbulence is increasing because of climate change.”

A 2021 report by the US National Transportation Safety Board indicated that turbulence accounted for 37.6 per cent of all accidents on larger commercial airlines between 2009 and 2018. Additionally, the US Federal Aviation Administration reported 146 serious injuries caused by turbulence from 2009 to 2021.

The aviation sector utilises specialised turbulence forecasts to plan smooth flight routes around turbulent air. While these forecasts have significantly improved over the past few decades, there is still considerable room for enhancement.

Future technological advances could enable pilots to remotely detect invisible clear-air turbulence from the cockpit in real time. However, the high costs currently make this technology impractical.

Also Read | ‘Bleeding ears, loud screams’: How 5 minutes of turbulence on Singapore Airlines plane left one dead, 71 hurt

For now, the best advice to passengers is to keep their seatbelt fastened. Remember, turbulence strong enough to cause injuries is relatively rare.

With inputs from agencies