It’s well known that air travel impacts the climate.
U.S. aircraft account for 11% of transportation-related greenhouse gas emissions. And as the EPA announced just last month, aircraft emissions contribute to climate change and “endanger the public health and welfare of current and future generations”, a first step toward regulation under the Clean Air Act.
“The U.S. transportation sector is a significant contributor to total U.S. and global anthropogenic GHG emissions. Aircraft remain the single largest GHG-emitting transportation source not yet subject to GHG standards in the U.S.”
What is not so well known is that the relationship also goes the other way.
How the climate impacts aircraft flight times
According to a study published earlier this year in Environmental Research Letters, a warmer climate can impact flight times in two ways. First, warmer air reduces lift force on the wings, increasing the likelihood of take-off weight restrictions. Second, a warmer atmosphere would increase the turbulence in the jet stream, leading to longer flight routes.
It’s this second effect, increased turbulence leading to longer flight routes, that caught my attention.
I’d always assumed flight paths were fairly constant. It’s intuitive that the fastest route to get from point A to point B for aircraft should be the same as it is for ground vehicles: a straight line (technically a great circle, the spherical equivalent).
As the graphic above illustrates, flight paths from New York to London can vary quite a bit, depending on jet stream winds.
— Max Galka (@galka_max) November 23, 2016
Here is the range of possible flight routes in both directions, eastbound (New York to London) and westbound (London to New York). The black line represents the physically shortest route between the two cities (on a 3D globe, it would appear as a straight line). The grey lines are the minimum-time routes under 90 simulated jet stream wind patterns.
What does the simulation tell us about the effect of climate change on flight times?
Under a warmer climate, eastbound transatlantic flights would likely be faster than they are today, assisted by stronger jet stream tailwinds. Likewise, westbound transatlantic flights would be slower for the exact opposite reason.
The westbound slowing effect would be larger than the eastbound speeding effect, leading to longer round trip flight times. When added up across a year’s worth of transatlantic flights, the effect would amount to about 2,000 additional airborne hours per year.
You can read the full study here.
More about my background
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