Transatlantic flights 'to get more turbulent'

Planes are already encountering stronger winds, scientists say

Flights across the North Atlantic could get a lot bumpier in the future if the climate changes as scientists expect.

Planes are already encountering stronger winds, and could now face more turbulence, according to research led from Reading University, UK.

The study, published in Nature Climate Change, suggests that by mid-century passengers will be bounced around more frequently and more strongly.

The zone in the North Atlantic affected by turbulence could also increase.

Reading's Dr Paul Williams said comfort was not the only consideration; there were financial consequences of bumpier airspace as well.

"It's certainly plausible that if flights get diverted more to fly around turbulence rather than through it then the amount of fuel that needs to be burnt will increase," he told BBC News.

"Fuel costs money, which airlines have to pay, and ultimately it could of course be passengers buying their tickets who see the prices go up."

Dr Williams was presenting his research here in Vienna at the European Union Geosciences (EGU) General Assembly.

It was undertaken with Dr Manoj Joshi from the University of East Anglia.

The scientists concentrated their investigation on the North Atlantic corridor, which some 600 flights cross each day to go between the Americas and Europe.

They used a supercomputer to simulate likely changes to air currents above 10km in altitude, such as the fast-moving jet stream.

There is evidence to suggest this has been blowing more strongly, and under some scenarios could be prone to more of the instabilities associated with turbulence as the Earth's climate warms.

The zone in the North Atlantic affected by turbulence could also increase

Williams and Joshi compared what was essentially an unchanged ("pre-industrial") climate with one that contained double the carbon dioxide. This could happen in the 2050s on present trends.

The modelling suggested the average strength of transatlantic turbulence could increase by between 10% and 40%, and the amount of airspace likely to contain significant turbulence by between 40% and 170%, where the most likely outcome is around 100%. In other words, a doubling of the amount of airspace affected.

"The probability of moderate or greater turbulence increases by 10.8%," said Dr Williams.

"'Moderate or greater turbulence' has a specific definition in aviation. It is turbulence that is strong enough to bounce the aircraft around with an acceleration of five metres per second squared, which is half of a g-force. For that, the seatbelt sign would certainly be on; it would be difficult to walk; drinks would get knocked over; you'd feel strain against your seatbelt."

The Nature Climate Change study is said to be the first to examine the future of aviation turbulence.

Figures are hard to come by but the costs of air turbulence in terms of injuries, plane damage and post-incident inquiries are thought to be in the region of $150m (£100m) a year.

Detecting clear-air turbulence (unstable air in clear blue skies) by remote sensing is difficult.

Currently, pilots rely a lot on reports from planes that have already made the journey across the Atlantic earlier in the day for information about probable flight conditions.

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