Last month, Phoenix was hit by a sweltering heatwave, with temperatures reaching 120 degrees Fahrenheit. It was so hot, American Airlines was forced to cancel 50 flights scheduled to depart Sky Harbor International Airport. The news of the cancellations spread far and wide, as people were interested in learning more about the physics of air travel and how extreme heat affects flying. And now a new study suggests that what happened in Phoenix may be just the tip of the rapidly melting iceberg.

Extreme heat is a byproduct of climate change. Experts agree that as the Earth’s temperature rises, these heatwaves will come more frequently, last longer, and be felt more intensely. And this will have an indelible effect on how we use airplanes for travel and commerce. A team of researchers at Columbia University set out to chart exactly how rising temperatures will affect the takeoff and landing performance of aircraft; their findings were published today in the journal Climatic Change.

just the tip of the rapidly melting iceberg

In short, air travel is about to get much, much more complicated. The researchers constructed performance models for five common commercial aircraft flying out of 19 major airports around the world and projected daily temperature increases based on the World Climate Research Program’s models. They concluded that, on average, 10–30 percent of flights taking off during the hottest part of the day will need to be much lighter to get off the ground.

This will affect both midsized and large commercial aircraft. Airports with short runways, as well as those located at high elevations, will also be severely impacted by rising temperatures brought on by climate change. This will likely lead to more delays and cancellations as airports and the major carriers grapple with how to respond to the new norm of extreme heat.

It will be more expensive for everyone, too. Airports will need to expend capital on building longer runways, while airlines will need to pour money into improving the technology that undergirds engine performance and airframe efficiency. Meanwhile, air traffic controllers will need to scramble schedules so heavier planes fly during cooler times of the day. (This practice is already used by airports in cities where extreme heat is more common. At Dubai International Airpot, some flights — but not all — arrive at night or in the early morning to avoid the extreme heat problem.)

more delays and cancellations

But some chaos in our future air travel will simply be unavoidable, the researchers state. “However, even with adaptation, potentially including new aircraft designs, takeoff performance will still likely be lower than it would have been given no climate change due to both the effects of reduced air density and degraded engine performance and thrust at higher temperatures,” they write. “This fact is true of all climate impacts: even if they can be adapted to, they still have a cost.”

That’s because extreme heat affects a plane’s ability to take off, especially smaller jets like those that service American Airlines’ regional routes out of Phoenix. Larger aircraft manufactured by Boeing and Airbus have maximum operating temperatures of 127 degrees Fahrenheit; smaller planes, like the Bombardier CRJ regional aircraft, can only operate at a maximum temperature of 118 degrees.

The science behind these maximum operating temperatures is pretty simple: hot air is less dense than colder air. So, the more extreme the temperature, the faster a plane needs to travel in order to achieve lift. Many airports don’t have long enough runways to allow planes to achieve this necessary speed during high heat.