Short-haul flights are the first target for sustainable aviation — but aerospace experts say banning them probably won't make the difference

• Regulators want to slash the number of short-haul flights to reduce aviation's carbon emissions.
• But experts told BI recent regulations might only have a small impact on reducing emissions.
• Shifting to greener fuels and enhancing green tech are essential for cleaner air travel.
• This article is part of "Future of Sustainable Aerospace," a series exploring the industry's green trends. 

To reduce carbon emissions and boost sustainability in the aviation industry, some governments and air-travel regulators are looking to ban or severely limit the number of short-haul flights.

Air travel is a dirty business: While the industry produces about 2% of global energy-related carbon emissions, a plane trip produces 100 times more carbon dioxide per hour than a train or bus ride. And short-haul flights, or routes of 932 miles or less, produce a disproportionate amount of carbon output. A report from the International Council on Clean Transportation, or ICCT, found that short-haul flights made up a third of all global aviation emissions in 2018.

But experts say bans alone won't significantly impact carbon emissions. Instead, reducing the number of short-haul flights, experimenting with new technologies, and investing in environmentally friendly travel alternatives may go further in reducing the aerospace industry's carbon footprint.

Regulations on short-haul flights aren't yet having the desired effect on emissions

Denmark announced last year that by 2025, Danes will be able to fly domestically on a "completely green route," meaning that at least one domestic flight would be carbon-free and that all domestic flights would be fossil-fuel-free by 2030. The move makes Denmark one of the first countries to signal publicly for stronger aviation-sustainability policies.

The Danish government also announced a "green tax" on passengers starting in 2025 to finance the country's green domestic route. The tax, converted from Danish krone, amounts to $9 for flights within Europe, $35 for medium-distance flights, and $56 for long-haul flights.

Similarly, earlier this year, the French government enacted a law banning any flights within the country that a train ride of 2-and-½ hours or less could replace.

The law initially seemed like a big win for climate activists, but the number of exceptions for international travel meant the law only impacted three routes between Paris-Orly Airport and the cities of Nantes, Bordeaux, and Lyon.

France's hyper-connected railway allows passengers to move between cities without changing travel patterns. Since high-speed trains already connect the impacted flight routes, potentially limiting the law's effects, the country's aviation industry isn't likely to see any big changes to its carbon footprint.

"In terms of absolute emissions reduction, it's not going to do too much," Sola Zheng, a researcher on the ICCT aviation program team, told Business Insider. "But it's a very good precedent that governments are willing to pull these kinds of levers."

But banning short-haul flights doesn't solve the industry's carbon-footprint problem, Giulio Mattioli, a transportation researcher at the Technical University of Dortmund in Germany, said. He told BI that banning these routes would have minimal environmental effects unless regulations address the industry holistically.

"Maybe ban short-haul flights, but then don't expect that to solve the problem," he said. "We need to talk about the long-haul flights as well."

Other strategies could curb the industry's emissions

The solution to the industry's emissions problem, Mattioli said, can be divided into a three-part strategy: avoid, shift, and improve. Avoiding would mean curbing the amount of flying we already do, or at least maintaining the same level of travel without increasing it; shifting would mean moving toward methods of travel, such as trains or buses, that create less pollution; and improving would mean enhancing sustainable aviation technology.

Mattioli told BI these strategies are all complementary, so the aviation industry must implement them simultaneously.

"It's only if we do those three things at the same time we have a chance of reducing emissions at the rate at which we should," Mattioli said.

Zheng said one emerging aviation technology that could make a difference is alternative power sources, such as hydrogen or electricity. Shorter flights are great candidates to test these advancements since electric and hydrogen-powered planes are often distance-constrained due to battery density and fueling needs. Because short-haul flights don't have to travel very far, the aviation industry won't have to change many flight patterns to test alternative power sources.

Sustainable aviation fuels have also recently gained industry attention because they're largely made of waste materials or renewable biomass. While aircraft could theoretically use these materials for longer flights, supply problems make their use as primary fuel unrealistic for the near future.

"You want to develop these other solutions for the shorter ones, so you can decarbonize both at the same rate," Zheng said.

Passengers can help reduce emissions, too

Flying continues to be a priority for travelers. A report from the International Civil Aviation Organization found that demand for air travel is expected to grow by about 4.3% a year over the next 20 years.

But Zheng said passengers are interested in making their travel greener and are willing to take steps to accomplish that goal. A Booking.com survey found that 76% of surveyed passengers want to make their travel more sustainable over the next year, and 43% of surveyed passengers are willing to pay more for it.

Zheng recommended flying on newer aircraft or booking an economy seat. Flights that dedicate more seats to standard seating can fit more people, reducing each passenger's carbon footprint.

"We have to experiment," she said. "There's never going to be a silver bullet."