Global and local carbon footprints of city of Hong Kong and Macao from 2000 to 2015

•For Hong Kong and Macao, their global footprints were approximately three times their direct emissions.•Direct CO2 emissions from Hong Kong and Macao stabilized, while their global footprints showed a continuous growth between 2000 and 2015.•For Hong Kong and Macao, the proportion of their carbon footprints for Mainland China in global footprints doubled on average between 2000 and 2015.•The enormous unfavorable balance of trade is the most critical driver of carbon footprints in trade of Hong Kong and Macao, followed by emission intensity. Hong Kong and Macao are featured with their urban metabolism as they heavily rely on the energy and resource supply from other regions. However, a comprehensive perspective is lacked to depict their CO2 emissions due to the independence of statistical data. Here we analyze the carbon footprints of Hong Kong and Macao. The direct energy-related emissions (Scope 1), the emissions of cross-boundary electricity (Scope 2), and the embodied emissions associated with trade (Scope 3) are examined. Scope 1 carbon footprints of the two areas were stabilized at 50 Mt, accounting for 0.6% of those from Mainland China in 2018. Their global footprints were approximately three times of their Scope 1 emissions, accompanied by a continuous growth between 2000 and 2015, and the contribution of their local footprints has doubled on average. Their Scope 3 emissions were mainly due to the enormous unfavorable balance of trade. Meanwhile, the increasing impact of imports’ higher emission intensity on their Scope 3 emissions should not be ignored. We suggest that Hong Kong and Macao should adjust their mitigation policies that focus only on Scope 1 emissions as developed cities outsourcing production through supply chains.