“Takeoff performance calculation will be fun.” This apparently sarcastic comment from a flight dispatcher at a European carrier appeared on Twitter after a weather forecast indicated a severe heat wave in Spain in mid-July. A “heat dome” with record-breaking temperatures also had just hit North America, causing 50 flight cancellations at Las Vegas McCarran International Airport on a single day, the Las Vegas Sun reported.

• Eurocontrol to release study on operational ramifications
• Societal changes may affect demand

The headline-grabbing phenomenon signals a new environmental front for aviation, which is accustomed to being described as a culprit of climate change. It is striving to cut its carbon footprint, looking for short-term ways to make aircraft operations more fuel-efficient, researching new technologies and promoting a ramp-up in the production of sustainable fuels.

Now the industry must also view itself as a potential casualty of global warming and brace accordingly.

Eurocontrol, the organization in charge of air traffic management in Europe for 41 member states, will publish in the coming weeks a report on how climate change will affect the industry. Four French research organizations specializing in aerospace and high-performance computing have also been investigating the subject. In both cases, preliminary results are available—and they are enlightening.

“We, too, are set to be massively impacted over the decades ahead,” says Eurocontrol Director General Eamonn Brennan.

Storms are growing in frequency and intensity, and initial estimates suggest that horizontal flight inefficiency due to major storms could increase to 4.0-4.2% by 2050, from 3.5% now. The trend is already being seen in en route air traffic flow management delays, Eurocontrol says.

Runway flooding is another increasing risk. By 2090, 178 coastal and low-lying airports could be affected around the world, Eurocontrol says. For every one-day closure at an airport due to full flooding, the cost of diverted and canceled flights is estimated to be around €3 million ($3.6 million) for medium-size airports and €18 million for large airports.

“Many airports are in the design phase or assessment phase of performing infrastructure upgrades to mitigate the impacts of climate stressors such as rising temperature, increased storm intensity and changes in precipitation,” says Juliana Scavuzzi, senior director for sustainability, environmental protection and legal affairs at Airports Council International. “Measures such as elevating critical electrical assets and implementing permeable pavement or nature-based solutions to help with stormwater drainage are examples of the measures airports are taking to protect their assets.”

Meanwhile, France’s ISAE-SupAero college of aerospace technology, aerospace research center ONERA, technology maturation institute IRT Saint-Exupery and modeling laboratory Cerfacs are working together on a holistic simulation. They are studying how climate change is going to affect commercial air transport— from aircraft takeoff performance to leisure travel demand. Cerfacs has long contributed to the work of the United Nation’s intergovernmental panel on climate change.

For example, they calculate that an Airbus A320 departing from a city in southern Europe will on average have to leave 30 seats empty during the hottest three months of the year, due to performance degradation as air temperature rises. The number of passengers (or at least airfares) left behind is calculated based on the 5% reduction in maximum takeoff weight the lower thrust and lift will require. This average means some flights will operate normally while others will be canceled.

That scenario will remain relatively exceptional until 2040. It will then become increasingly common, until it turns into a norm in 2100, the French study shows.

Consequences may also be expected in cruise flight, says ISAE researcher Nicolas Gourdain.

Clear-air turbulence (CAT), a hard-to-detect phenomenon causing discomfort for passengers and posing a safety risk to flight attendants, peaks at higher altitudes. One of the sources of CAT is a thermal gradient that is poised to strengthen, Gourdain explains. Current cruise altitudes are close to 30,000 ft. in part because that is higher than the usual level of powerful CAT. But with global warming, the altitude of maximum-power CAT will rise.

In parallel, a warmer atmosphere will cause greater quantities of water vapor to be found in the air at 30,000 ft. Therefore, the risk of icing increases at that flight level, Gourdain says.

Climate change may also generate societal changes. Many tourists may begin to view destinations such as Greece as too hot for summer holidays. It is entirely possible the result could be a drop in demand for such destinations of 20-30% starting in 2030, Gourdain suggests.

All these anticipated consequences could be dealt with in some manner: Runways could be extended, a new peak season for leisure travel could be factored in, and cruise altitudes could be altered. But such measures would come at a cost, and in some cases they may not even be doable.

Gourdain says the first phase of the joint multidisciplinary work, which began in 2019, has been a success because of the synergies created. A key focus is mutual understanding among the specialists—experts in aircraft aerodynamics had to fathom climate models, for instance. And while previous studies of these issues were conducted, none encompassed as many aspects as this new effort. 

The very notion of risk can differ between fields of study. Risk can refer to strong turbulence, economic viability or a society’s resilience to climate change, Gourdain says.

Differences in how time and space are viewed also had to be factored in. While an aircraft aerodynamics expert thinks in micrometers and seconds, a climate scientist will focus on kilometers and years. The tools and methods differ as well, Gourdain points out.

A new, three-year phase for the study is beginning. Models will be refined, notably for lift and engine thrust as functions of humidity and temperature, Gourdain says. Aircraft will be modeled from three standpoints: as an engineered object, a societal artifact and an economic asset.