LONDON, (Reuters) – Wizz Air’s boss in Hungary criticized traditional airlines such as Air France-KLM or Lufthansa for their sustainability credentials. He claimed that business class flight was harmful to the environment.

As climate change worries grow, so has the carbon dioxide emissions from airlines.

Jozsef Varadi, Chief Executive of Wizz Air, stated at the CAPA online industry conference that short-haul flight passengers had no business class.

It is not necessary to fly in business class on short flights. On Wednesday, he stated that business passengers take up more space so their environmental footprints are much larger.

These comments were made as world leaders gathered Wednesday at the COP26 Climate Conference in Glasgow. There, a variety of announcements regarding the greening transportation system were anticipated.

These new partners opened up a new arena in the fight between older, more established airlines and newer low-cost ones over how to tackle the environment.

Lufthansa’s chief Carsten Spohr has been critical of low-cost carriers, saying that they are offering unrealistically low prices to spur travel.

Wizz and other budget airlines offer only one kind of flying. Lufthansa, on the other hand, offers more spacious flights for people who pay more.

Varadi declared that sustainability was about change.

EasyJet, a low-cost airline from Britain, said that it would present more details about its net zero roadmap over the next few months. This comes after having committed to net-zero emission by 2050.

British Airways’ owner IAG (LON) has agreed to buy 220,000 tonnes sustainable aviation fuel (SAF), from Velocys in 10 years as part of its aim of using 10% of SAF by 2030.