Global carbon emission implications of China’s demographic ageing

China’s rapidly ageing exerts increasingly complex impacts on global carbon emissions. While most studies primarily examined domestic carbon of elderly, its global implications remain understudies. This study develops a novel provincial-global multi-regional input–output (MRIO) model, integrating Chinese Household Expenditure Surveys, to quantify carbon footprints of older adults. The results reveal that although the elderly show relatively lower per capita emissions (2.63 t per capita in 2020), their rising demographic share (from 8.8% in 2005 to 12.5% in 2020) and annual growth rate of emissions (11.77%) represent ageing as a significant driver of global emissions. Key sources, including food and residence, while emissions embodied in international trade, particularly from Brazil, Australia, and Russia, are increasingly prominent. At the sectoral level, power generation and agriculture dominate both domestic and imported emissions. The findings highlight the urgency of incorporating demographic ageing into carbon mitigation strategies and addressing foreign emissions embedded in elderly consumption.