July has been the warmest month on record in Earth's history, with temperatures hitting record levels across the globe and in nearly every part of the U.S. With climate change getting continually worse, airlines will likely continue to have to make significant adjustments to passenger and fuel loads to cope with the extreme temperatures and weather fluctuations.

Even before changes are made to aircraft loads, many airlines have been forced to invest in additional resources such as carts carrying water and Gatorade to thousands of employees who have to work on the tarmac in the extreme heat.

With warmer air being less dense, aircraft departing in hot weather often require higher takeoff speeds and more runway to lift off the ground - weight from passengers and cargo hinders that effort, thus in the coming years, airlines will likely have to cut loads to operate flights as normal in the extreme heat. Indeed, a 2017 study from the Climatic Change journal found that in the coming decades up to 30% of flights in an airline's schedule will have their payload affected by extreme heat, a staggering figure!

Extreme heat will have implications for all airlines in the U.S., but will particularly strain operations in the Southwest at hub airports like Las Vegas (LAS), Phoenix (PHX), Dallas (DFW), Houston (IAH), and possibly even Salt Lake City (SLC). 

Already this summer airline passengers have voluntarily given up their seats (for compensation) such that aircraft could take off safely in triple-digit temperatures. Moreover, on July 17, some passengers on a Delta Air Lines flight experienced heat stroke after the plane's air conditioning system broke while sitting on the tarmac.

Extreme temperatures have the most impact on smaller aircraft, and back in 2017 extreme temperatures forced the cancellation of some 60 flights at Phoenix Sky-Harbor Airport (PHX), the majority of which were operated by smaller, regional jets. Temperatures above 120 degrees Fahrenheit can have a considerable impact on safety instruments onboard the plane which can make it challenging to fly planes safely and reliably when temperatures get that hot. These factors compound with high altitude and high humidity which also affect takeoff and landing operations. 

As a whole, passengers should expect to see more and more delays or cancellations as climate change continually gets worse. While airlines will complimentarily rebook passengers or provide refunds for those who decline the rebooking, passengers should still plan ahead in cases where temperatures are well above normal. 

Airlines could decide in the future to add more refueling stops if they choose to carry less fuel instead of passengers or bags, but with fuel costs consistently variable, it is likely they will choose the latter option. That, of course, could lead to increased fares if airlines need to make up the money they give out in vouchers for those who choose to give up their seat. Regardless, whatever ends up happening will soon be upon us as airports around the country continue to see record heat levels this summer.