Air turbulence is getting worse on flights because of climate change, with the jetstream becoming choppier since the end of 1970s, scientists have found.
The University of Reading has discovered that the jetstream has become 15 per cent more affected by wind shear in the upper atmosphere over the North Atlantic since satellites began observing it in 1979.
Over the same period the number of passengers and crew getting seriously injured from turbulence globally has doubled from one in a million to two in a million - meaning around 8,000 people a year are now impacted.
Wind shear - the increase in wind speed at high altitudes - causes invisible turbulence which can be severe enough to throw passengers from their seats.
And while global warming has caused temperatures to rise in the lower atmosphere, they have cooled in the stratosphere, creating a 'tug-of-war' effect and making flights more bumpy.
Researchers predict that the problem would get worse as the climate continued to deteriorate through global warming.
Simon Lee, a doctoral student in Meteorology at the University of Reading, said: "We looked for the first time at the wind shear, where significant change has previously gone unnoticed.
"Over the last four decades, temperatures have risen most rapidly over the Arctic, whilst in the stratosphere – around 12 km above the surface – they have cooled.
"This has created a tug-of-war effect, where surface temperature changes act to slow the jet down, while temperature changes higher up act to speed it up.
"This has serious implications for airlines, as passengers and crew would face a bigger risk of injury."
Tens of thousands of planes encounter severe turbulence every year, with an estimated cost to the global aviation sector of up to a billion dollars annually, through flight delays, injuries to cabin crew and passengers, and structural damage to aircraft.
A previous study by Reading University predicted that climate change will make severe turbulence up to three times more common by 2050-80.
It will also cause the jetstream to speed up meaning flights to the US will take longer, but coming home will be quicker.
Professor Paul Williams from the University of Reading's Department of Meteorology, who led the new study, said: "I do think flights will become bumpier in future. And we'll likely see delayed flights for people travelling to the US from Britain.
"We're already seeing record-breaking times coming back from the US and we'll see further records broken I suspect."
Prof Williams is currently working with aircraft engineers on how to make planes fit for warmer and bumpier airspace.
The research was published in the journal Nature.
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