What does turbulence have to do with global warming, you ask? Very simple. Global warming causes the climate to go increasingly haywire as more carbon dioxide is introduced into the atmosphere. You feel it on the ground, of course, but it also plays games up where airplanes hang out. Among other things, the jet stream speeds up, which churns up the air and creates a less-smooth path for planes to fly through, meaning they get thrown around more. It shouldn't cause a lot of crashes, but what it will do is make less-comfortable flights, damage the planes, injure more passengers who don't have their seatbelts on and crack their heads on the roof of the cabin, and force flights to get rerouted more often.
According to the Guardian, by 2050, flights between Europe and North America are projected to undergo turbulence twice as often as now, with the intensity of turbulence projected to rise by anywhere from 10-40%. And let's be clear: that's for turbulence in good weather. That doesn't take into account turbulence during storms, which as we've long since established are likely to get stronger and more common.
'So just avoid the turbulent bits and fly in the smoother part of the atmosphere', you say? If they knew how to do that, they'd be doing it already. Scientists haven't yet really figured out how to tell where turbulence is likely to happen. They're working on it, and the people at British Airways have a dim understanding, but nobody's really got it pegged yet. Besides, rerouting to smooth areas would make for longer flights, more delays, more spent fuel, and as a result of all that, higher ticket prices.
Speaking of prices, the source report, from Nature Climate Change, is here if you've got $32 on hand to read it.