Climate change may make flights bumpier

AFP-JIJI

Flights will become bumpier as global warming destabilizes air currents at altitudes used by commercial airliners, climate scientists warned Monday.

Already, atmospheric turbulence injures hundreds of airline passengers each year, sometimes fatally, damaging aircraft and costing the industry an estimated $150 million, scientists said.

“Climate change is not just warming the Earth’s surface, it is also changing the atmospheric winds 10 km high where planes fly,” said study coauthor Paul Williams of the University of Reading in England. “That is making the atmosphere more vulnerable to the instability that creates clear-air turbulence. Our research suggests that we’ll be seeing the ‘fasten seat belts’ sign turned on more often in the decades ahead.”

Turbulence is mainly caused by vertical airflow, up-draughts and down-draughts near clouds and thunderstorms. Clear-air turbulence, which cannot be picked up by satellite or traditional radar, is linked to atmospheric jet streams, which are projected to strengthen with climate change.

The study authors used simulations of the North Atlantic jet stream, which is driven by temperature differences between colliding Arctic and tropical air. The jet stream affects traffic in the aviation corridor between Europe and North America — one of the world’s busiest with about 300 eastbound and 300 westbound flights per day.

They found that a doubling of carbon dioxide in the atmosphere from preindustrial levels, predicted within 40 years, would cause turbulence to be 10 to 40 percent more forceful at typical cruising altitudes.

“Turbulence strong enough to make walking difficult and to dislodge unsecured objects is likely to become twice as common in trans-Atlantic airspace by the middle of this century,” Williams said, adding, “This could also increase the risk of injury to passengers and crew,” especially in winter when Northern Hemisphere clear-air turbulence is thought to be most intense.

Williams said carbon dioxide causes nonuniform warming, which increases the jet-stream winds and “creates more turbulence,” he explained.

The study, published in the journal Nature Climate Change, said planes already spent about 1 percent of their time in the skies in strong clear-air turbulence. This is the first study to actually measure the projected impact of climate change, the authors said.

“Flight paths may need to become more convoluted to avoid patches of turbulence that are stronger and more frequent, in which journey times will lengthen and fuel consumption and emissions will increase,” they wrote.

“Aviation is partly responsible for changing the climate in the first place,” Williams added. “It is ironic that the climate looks set to exact its revenge by creating a more turbulent atmosphere for flying.”