Abstract Introduction Literature review and hypothesis development Methodology Results Conclusions Supplemental material References Full Article Figures & data References Supplemental Citations Metrics Reprints & Permissions PDF EPUB Abstract Air travel is predicted to grow over the coming decades contributing to carbon emissions. Airlines have offered voluntary carbon offsetting for over a decade, yet less than 10% of air travellers purchase them. Previous studies ignore the broader policy or social context of sustainable transport and aviation offsetting. In a natural experiment, a panel of the same Australian residents was tracked over a three-year period before and after the historic COP21. A novel hierarchical model was also tested using Partial Least Squares SEM. Although behaviour specific attitudes and social norms were more influential at encouraging aviation carbon offsetting, global policy knowledge and effectiveness of climate change policies play an important role. Although no changes in ratings were detected over a three-year period, the effect of social norms on encouraging aviation offsetting became stronger in later years. Implications and future research directions to better understand the political and social context of carbon offsetting and sustainable transport are provided.