Why air turbulence could be about to get a whole lot worse

In nonfatal accidents, turbulence is the leading cause of injuries to flight attendants and passengers, according to the Federal Aviation Administration, and it's one of the most common airline accident types today, according to the US National Transportation Safety Board. It costs US airlines -- due to injuries, delays and damages -- up to $500m per year, according to the National Center for Atmospheric Research. "There is a scale for measuring how strong turbulence is," says Paul Williams, a professor of atmospheric science at the University of Reading in the UK. "There's light turbulence, which is a bit of strain against your seat belt, but food service can continue and you can probably walk around the cabin, maybe with some difficulty. "Then there's moderate turbulence, a definite strain against seat belts, anything that's not secured will be dislodged, and walking is difficult; flight attendants are usually instructed to take their seats. "The worst kind is severe turbulence: this is stronger than gravity, so it can pin you to your seat and if you're not wearing your seat belt you'll be tossed around inside the cabin. This is the kind of turbulence that causes serious Injuries -- it's been known to break bones, for example." About 65,000 aircraft suffer moderate turbulence every year in the US, and about 5,500 run into severe turbulence. These numbers, however, might be destined to grow. Williams believes that climate change is modifying turbulence, and started studying the subject in 2013. "We ran some computer simulations and found that severe turbulence could double or triple in the coming decades," he says. The findings, which were later confirmed by observations, highlight a type of turbulence called "clear air turbulence," which isn't connected to any visual clues such as storms or clouds. Unlike regular turbulence, it hits suddenly and is hard to avoid.<br/>