The climate crisis will keep making transatlantic flights way faster

A flight from London to New York broke the all-time subsonic transatlantic record thanks to Storm Ciara, but a faster jet stream will actually slow flights down more


11 Feb 2020
Nicolas Economou/NurPhoto via Getty Images

No one enjoys a transatlantic flight. But passengers on BA112 – the red-eye, overnight flight from John F Kennedy Airport in New York to London Heathrow – suffered a little less than most this weekend. Their flight, which should usually take more than six-and-a-half hours, instead took four hours 56 minutes, landing on the tarmac significantly earlier than expected. The cause? Storm Ciara, which caused wind speeds in the jet stream, the band of wind high in the Earth’s atmosphere which propelled the plane to its destination, to reach 260mph at their fastest.

It was the third time the subsonic transatlantic air travel speed record was broken since 2015. And it’s partly down to the climate crisis. “Things like this record-breaking transatlantic flight are consistent with climate change occurring,” says Simon Lee at Reading University, who has investigated the impact of the climate crisis on flight times. The clustering of recent new records is an indication of the impact of the climate crisis similar to the record-breaking maximum temperatures we see in successive summers.

But while Lee reckons climate change is playing a part in bringing down flight times, things are a little more complicated than that. He and his colleagues, including Paul Williams at Reading University, are looking at the precise contribution the climate crisis plays in flight times. But they also acknowledge that airlines are taking advantage of the variations in the jet streams to improve their flight times.

The jet stream that crosses the North Atlantic is directly on the flight path for flight between the US and UK flights, says Mike Byrne, who studies the climate at the universities of St Andrews and Oxford. “The temperature difference between the equator, where it’s warm, and the Arctic, where it’s very cold, drives the jet stream,” says Byrne. Climate models developed by him and others forecast that the difference between the rapidly-warming Arctic – which is heating up twice as fast as the rest of the world – and the equator means that the jet stream is getting stronger at a height of around twelve kilometres above the Earth’s surface: right where planes travel.

“It’s a tug of war between differences in the surface atmosphere and the higher atmosphere,” says Byrne. “Our best prediction of how the jet stream will change is that it should get stronger.”

Airlines are acutely aware of that, and are making decisions to benefit from the positive effects of a stronger jet stream. “If there are more permanent moves in jet streams that would potentially have a greater impact on regular flight times,” says John Strickland. “Normally eastbound transatlantic flights are around an hour quicker than westbound. Strong winds push the aircraft along faster eastbound, or conversely slower westbound.” According to Strickland, airlines adjust their flight plans based on the location of the jet streams to take advantage of their positive impact, or to mitigate their negative effects.

And there are negative effects: lots of them. As you’d expect, if the wind in one direction (eastbound) is getting stronger, providing fairer tailwinds for flights travelling from the US to the UK, then the impact on flights in the opposite direction (westbound) is negative. Flying into a headwind will increase flight time on journeys to the US from the UK – and by more than it decreases flight times in the opposite direction. The end result, more time in the air overall on a two-leg journey, creates a vicious circle. Aircraft fly for longer – 2,000 hours across all flights per year, according to research from Reading University – which means more fuel is burned, which makes air travel more expensive and more importantly, more damaging to the environment, fuelling further global warming.

The effect of the predicted impact of the climate crisis on the jet stream makes for sobering reading: the average tailwind increases nearly 15 per cent when the concentration of carbon dioxide in the atmosphere is doubled, making it twice as likely that an eastbound flight will take less than five hours 20 minutes from New York to London, and a westbound flight would take more than seven hours from London to New York. But that extra time flying means using up an extra 7.2 million gallons of jet fuel, and emitting an extra 70 million kilograms of carbon dioxide – all of which is bad for the planet.

Besides, faster journeys aren’t always better ones. The climate crisis has made the jet stream stronger in the North Atlantic, but it has also increased vertical wind shear, an increase in wind speed at higher altitudes. According to research by Lee, the jet stream has seen an increase in wind shear of around 15 percent since 1979. That wind shear causes clear-air turbulence, violently shaking planes as they fly through the sky. Though your flight time in one direction may end up being quicker, in both directions it’ll be a lot more bumpy. “The only thing it benefits is you can get from New York to London quicker,” says Lee. “That’s the only benefit. Everything else is much worse, and though your flight is quicker, it’s more turbulent.”

That’s even without thinking of the broader impacts of the climate crisis. We know that climate change is responsible for melting ice and rising sea levels. It could well be that your return flight from New York is a little quicker, but flying to other destinations may be impractical if rising tides wipe them out entirely. “A few minutes off your flight time is a nice thing, but ultimately this will be completely swamped by the negative impacts of the climate crisis, which will adversely affect people all over the globe,” says Byrne.

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