This article explores the role of the International Civil Aviation Organization (ICAO) in regulating civil aircraft engine emissions in the age of climate change. The Kyoto Protocol allocates authority for international aviation emissions to ICAO, but the organisation has failed to provide effective regulation over the past fourteen years. This article examines why ICAO was granted such authority, what might account for ICAO’s failure and explores the role of ICAO in the future. It argues that the ICAO should not be the sole regulatory authority for the aviation industry, but that it has an important contribution to make in terms of technical expertise and auditing capacity.