Marte van der Graaf does not hold back when it comes to criticizing airlines' efforts to protect the environment.

"It's difficult to take the aviation industry's net-zero targets seriously," she said. Graf is an aviation policy officer in Germany for the NGO Transport & Environment, which focuses on promoting sustainable transportation. "The aviation sector must significantly reduce its consumption of fossil fuels in the next decades. But things are going in the opposite direction at the moment," she said.

More and more people flying

As climate change threatens the planet, the industry's CO2 emissions continue to rise. And according to future projections, more and more people will be flying in the coming years. That has environmental groups worried. "Green growth and CO2-neutral air traffic remain an illusion," said the Stay Grounded network, which campaigns for less air traffic.

Nevertheless, the aviation industry has set ambitious goals for itself.

"The goal is to be climate-neutral by 2050," said Wolf-Dietrich Kindt, head of climate and environmental protection at the Federal Association of the German Aviation Industry. German airlines have invested billions of euros in renewing their fleets in recent decades, he added, making it possible to drastically reduce jet fuel use and emissions.

"That is a very significant achievement," said Kindt.

New planes are more efficient

The most achievable way to reduce emissions at the moment is simply to make planes more fuel efficient. And according to experts, fuel efficiency can be increased by 20% with each new generation of aircraft.

The EU has imposed regulations for airlines in the bloc, including blending quotas for more climate-friendly fuels, which come with a higher price tag. Additionally, the EU emissions trading system, an air traffic tax in Germany as well as a possible jet fuel tax have put European airlines at a disadvantage against competing non-EU airlines. As a result, there isn't as much investment in newer aircraft as there should be.

Markus Fischer, director of the aerospace division at the German Aerospace Center, also believes in the innovative power of the aviation sector. "The industry has made a big effort to increase its efficiency through better engines and aerodynamics," he said.

He pointed out that the average fuel consumption per seat and kilometer today is only a third of what it was 50 years ago, though admitted that this still wasn't enough. The solution is alternative, non-fossil fuels.

Alternative fuels only available in small quantities

But this is precisely where the industry is struggling. Some airlines are promising electric aircraft for short-haul flights. Airbus, meanwhile, has announced a hydrogen-powered aircraft that will be ready to fly in 2035.

Yet sustainable fuels produced from renewable energy or biomass, which could replace fossil jet fuel in the short term and are less harmful to the climate, will only be available in small quantities — and at very high prices — for the foreseeable future. "There are currently no revolutionary and immediately available solutions for emission-free aviation due to major technological challenges," according to the German Aerospace Center.

Michael Haid wants to change that. He's head of EDL Anlagenbau, a company that is planning one of the world's first factories for the industrial production of green jet fuel near Leipzig.

"It will be very difficult to reach the goal of climate-neutral flying by 2050," he said. "Especially when you see how long it all takes." He blames the EU for imposing complicated regulations, which have caused delays. They've been planning the production of their fuel, called HyKero, since 2021, but production will not start before the end of 2027.

Is climate-neutral air travel even possible?

There are additional barriers to achieving climate-neutral aviation. CO2 accounts for only a portion of the climate-damaging emissions from an aircraft.

Markus Fischer of the German Aerospace Center estimates that the "non-CO2 effects" are responsible for at least 50% of the environmental impact of flying. Contrails, for example, contribute to global warming.

"Even without alternative fuels, you can do a lot to help the environment," he said. Negative effects of flying can be reduced simply by modifying flight speed, altitude and routes, for example.

And yet the industry itself does not seem to believe it will reach the goal of climate-neutral aviation by 2050. The International Air Transport Association, for example, speaks of CO2 neutrality that is likely to only be achieved through carbon offsetting.

"Compensation measures are a bogus solution for the environment," said Marte van der Graaf of Transport & Environment. "Airlines should stop using them as an excuse to postpone real climate protection measures."

She put it bluntly: "The only truly green flight is the one that stays on the ground."

This article was originally written in German.