The two bodies will develop the first unified approach for calculating flight emissions, allowing passengers to estimate their carbon footprint when they fly.

Travalyst was founded by Prince Harry in 2019 and is backed by brands including Booking.com, Travelport, Expedia and Tripadvisor, although no airlines are involved.

Sally Davey, Travalyst chief executive, said: “This is the first time that airlines and the travel technology sector have come together in this way. 

“As such it is a milestone moment in the decarbonisation of the sector. In the face of the climate emergency, travellers want and need clear and unequivocal information about their carbon footprint on which to base travel decisions. 

“Today we are bringing some of the leading travel brands around the table with the world’s leading airline association, with the aim of easily providing consumers with the most accurate carbon calculations.”  

Travalyst and Iata will align CO2 emission calculations and develop a shared view on how to account for sustainable aviation fuel.  

Iata director general Willie Walsh said: “Consumers want to understand the environmental impact of their travels. Both Travalyst and Iata are continuously working to improve their methodologies by incorporating emerging knowledge of climate impacts. 

“So we are working together to provide the consumer with easy access to consistent calculations of the environmental cost of their travel.”