Why does airplane turbulence seem to be increasing?

By ThreeNews' resident weather expert Heather Keats.If you're about to board a plane - don't look up 'turbulence' 'planes' and 'climate change'. It's a search which provides a high number of results, documenting recent flights where severe turbulence has resulted in injuries, or even death.Planes fly in the atmosphere. Turbulence happens in the atmosphere. Climate change affects the atmosphere.So, is it reasonable to conclude any shift in climate will have a knock-on effect for flight turbulence?READ MORE: Keen to visit Machu Picchu? Here are all your options for seeing the ancient wonderWhat causes turbulence?Storms, mountains and jet streams are three common causes of flight turbulence.Storms are the easiest to avoid - because pilots can see them. A plane is designed to withstand lightning strikes from a thunderstorm, but pilots will only fly through them if they have to. Generally speaking, they'll fly up, down or around them.Air above mountains or mountain ranges also cause turbulence. Mountains, ranges and alps are well documented these days. Pilots know where they are, so they can prepare for turbulence.Atmospheric air currents, aptly named jet streams, are used by airlines to assist air travel. Jet streams are high-altitude corridors of fast-moving air. A plane flying with the current can cut down on fuel consumption and speed up their trip. However, they can also cause turbulence. But pilots know this and are able to pre-empt the disruption.Noticing a pattern?Most turbulence you experience in a plane is anticipated. A pilot who understands the visual cues is able to prepare the cabin, and mitigate risks from expected turbulence. Your seat belt is on, the cabin crew are no longer serving hot drinks and the toilet is a no-go.It's the CAT that's the problem, which stands for clear-air turbulence.When a flight has a newsworthy turbulence event, most of the time it's because they've plunged suddenly mid-air, throwing passengers and crew around like ragdolls. Broken bones, lacerations, heart attacks and coffee burns have been in the headlines recently as a result.Clear-air turbulence is likely to blame.It happens when there are no visual cues, such as clouds.According to a study by the University of Chicago professor Timothy Shaw and scientist Osamu Miyawaki of the National Center for Atmospheric Research published in November, upper-level jet stream winds get faster per degree (C) of warming."The results can be used to explain projected changes in commercial flight times, record-breaking winds, clear-air turbulence and a potential increase in severe weather occurrence under climate change," the study said.Other academic research also published last year, this time by Paul Williams, Isabel Smith and Mark Prosser of the University of Reading, found aviation turbulence increased with climate change.A summary of the research released by the university said: "We find that severe clear-air turbulence has increased by 55 per cent over the North Atlantic and 41 per cent over the US since 1979. It does go up and down from one year to the next, but there's a clear long-term upward trend, consistent with the expected effects of climate change. We find similar increases on other busy flight routes over Europe, the Middle East and the South Atlantic."And, of course, climate change is also linked to an increase in severe weather.The odds of being injured from severe turbulence is very low. We may see an increase in reported severe turbulence events in part due to climate change or from an increased number of flights.As a passenger, I wouldn't be too concerned as long as I was wearing a seatbelt.This story originally appeared on Stuff and was republished with permission.