Hong Kong International Airport is among the top polluting hubs in the world, a UK thinktank has found.

On Wednesday, new data from global affairs thinktank ODI Global ranked Hong Kong’s airport as the world’s sixth most polluting in terms of flight CO2 emissions, and second in Asia-Pacific.

The study, based on 2023 data from the International Council on Clean Transportation, concluded that the fossil-fuel dependent aviation sector would be the fifth-largest emitter if it were a country.

Hong Kong emitted 15.1 million tonnes of CO2, and saw 138,764 flights, in 2023.

Seoul was Asia-Pacific’s most polluting airport, responsible for 16.8 million tonnes of CO2 emissions in 2023. Dubai topped the global ranking with 23.2 million tonnes of CO2, followed by London’s Heathrow.

The research also showed that Hong Kong’s airport was a significant source of local pollutants – it ranks ninth in the world, emitting 4,572 tonnes of nitrogen oxides in 2023.

The thinktank warned against reliance on so-called “sustainable” aviation fuels to bring down emissions, citing “high production costs and price premiums, limited policy support, weak long-term offtake commitments, bankability challenges and constraints on feedstock availability and sustainability.”

It also said that jet fuel emissions are predicted to increase and eat up future carbon budget: “The sector’s own high-growth scenario projects passenger demand could increase by 3.3% annually, from 9.0 trillion revenue passenger-kilometers (RPKs) in 2024 to 21.9 trillion RPKs in 2050. Between now and 2050, aviation is projected to consume 15% of the remaining carbon budget associated with 1.7ºC of warming.”

HKFP has reached out to the Environmental Protection Department and the Airport Authority for comment.