Aviation is responsible for around 2.5% of the carbon emissions that are warming the planet, according to the International Energy Agency.

Delta, which claims to have been carbon neutral since March 2020 after spending £22.4 million a year on carbon offsetting schemes, pledged to spend a further $1 billion over the next decade to "cancel out" all emissions it creates.

Andreas Schafer, professor of energy and transport at University College London, reportedly said it will "cost trillions rather than billions of dollars" to move the global aviation sector to net-zero carbon emissions.

Preliminary results from his team’s research suggested airfares would need to increase by 10%-20% to cover the costs.

"Over time, it’s going to cost us all more, but it’s the right approach that we must take," Bastian told the BBC.

He said the climate change conversation is the "biggest long-term challenge this industry faces". 

"We’re in an industry that’s classified as hard to decarbonise because we don’t have the bio-fuels or the sustainable aviation fuels (SAFs) en masse yet that we’re going to need," he added.

Delta is said to be aiming to use 10% SAF by the end of 2030.

"All forms of travel are on the way back," Bastian continued.

"Families are the part of the travelling public that we’re most happy to see, because there’s been some really difficult stories over time of families not being able to connect for long [periods]".