We know a warming planet affects the ground, as droughts and wildfires become more frequent. We know it affects the water, as coral reefs die and sea levels rise. Now we're learning it affects the air in surprising way -- in particular, air travel.
In a recent paper, three environmental scientists pointed out some basic physics: "As air temperatures rise at constant pressure, air density declines, resulting in less lift generation by an aircraft wing." Thus, on particularly hot days, airliners of virtually any size will have to use longer runways in order to get airborne, or decrease weight to fly. Since building longer runways would take time and money, the quickest solution may mean flying with fewer passengers -- about a dozen from a typical flight -- or less baggage. Would airlines limit one bag to a passenger? Would they simply under-book their flights or actually remove travelers right before take-off? For an industry with some recent public-relations issues, the stakes are high.
A more customer-friendly solution would be to build aircraft with larger wingspans, creating a greater area for lift. Such a project is certainly feasible, but is also expensive and slow. Another possibility is to move departures for long summer flight to the evening, when it's cooler, but that could mean a huge change in airlines' schedules and traveler convenience.
That's not the only way rising heat is affecting air travel. For several days in June, temperatures at Sky Harbor International Airport in Phoenix were so high, American Airlines grounded its regional planes. The Bombardier CRJ aircraft has a maximum operating temperature of 118 degrees; the forecast for the day was 120 degrees. If temperatures continue to climb, flights on a Boeing (126 degrees) or an Airbus (127 degrees) could be delayed or canceled as well.
And it gets worse. Climate change is affecting the jet stream, causing more turbulence during flights. Paul D. Williams, a professor of atmospheric science, recently published a paper using computer models. By about 2050, they predicted a 59% increase in light turbulence, a 94% increase in moderate turbulence (which can jostle items on tray tables), and a 149% increase in severe turbulence -- during which, according to the FAA, "occupants are forced violently against seat belts" and "walking is impossible." Williams concluded, "[T]urbulence diagnostics generally gain probability...when the atmospheric carbon dioxide concentration is doubled," which is on pace to happen in just a few decades.
Williams' models focused on transatlantic flights in winter, but the jet stream is still changing and getting stronger, with unforeseen effects. For example, in January 2015, a flight from New York to London lasted almost an hour shorter than usual because of the jet stream's strong tail wind. But flights from London to New York faced such strong headwinds that they had to stop in Maine to refuel.
Taken together, it appears climate change will make air travel less convenient, more hazardous, and more costly -- if heat allows the planes to get off the ground at all.
Jason Ginsburg co-produced of Antarctica for Discovery Channel and Ask the Astronaut for Science Channel. He manages the science, nature, and adventure content for Discovery+.
Ethan D. Coffel, Terence R. Thompson, Radley M. Horton, "The Impacts of Rising Temperatures on Aircraft Takeoff Performance", Climatic Change
Zachary Hansen, "It's So Hot in Phoenix, They Can't Fly Planes", The Arizona Republic/USA Today
Andrew J. Hawkins, "Climate Change is Going to Make Air Travel Even More Nightmarish, Study Says", The Verge
Federal Aviation Administration, "Aeronautical Instruction Manual"
Kendra Pierre-Louis, "Climate Change Could Make Severe Turbulence Even Worse", Popular Science
Paul D. Williams, "Increased Light, Moderate, and Severe Clear-Air Turbulence in Response to Climate Change", Advances in Atmospheric Science