Beyond the runway - Quantifying the climate impact of international catering waste.

International flights generate substantial volumes of waste that pose a unique environmental challenge, as strict biosecurity regulations require it to be disposed of through destructive methods across the world. However, the impact on the world's climate of managing this waste remains unquantified and largely disregarded in aviation mitigation discussions. This study presents the first analysis of the contribution of cabin waste management to climate change, developing a novel methodology that combines passenger movement data with waste generation factors to quantify volumes, composition, and greenhouse gas emissions of national cabin waste. Applied to the United Kingdom as a case study, our analysis estimates that that approximately 89,000 tonnes of cabin waste entered the UK in 2022. This generated between 10,400 and 40,500 tonnes of CO2 equivalent due to the mandated disposal in landfill or incineration. This climate impact is driven by regulatory requirements that prevent more sustainable waste treatment methods, and by slow industry innovations. Our model demonstrates that allowing cabin waste to be treated like domestic waste could generate climate benefits of 33,900 tonnes CO2 equivalent, through material and energy recovery. With aviation movements projected to grow through to 2050, we identify specific actions that could enable more sustainable cabin waste treatment while maintaining high levels of biosecurity. This research provides a replicable framework for other nations to quantify their cabin waste climate impacts, and evidence-based pathways for urgent regulation and operational reform.