Urban economy's carbon flow through external trade: Spatial-temporal evolution for Macao

A typical heterotrophic urban economy relies heavily on external trade, which inevitably generates carbon emissions outside its administrative boundary. Based on the most updated multi-regional input-output table, this study investigates the evolution of energy-related carbon flows embodied in Macao's external trade. The results show that both carbon inflows and outflows maintain a growing trend from 2000 to 2013 in general, accompanied with some rise and falls during this period. Total carbon imports increase from 3.67E+06 t in 2000 to 1.24E+07 t in 2013, whose main contributor changes from Sector Textiles and Wearing Apparel in 2000 to Sector Electricity, Gas and Water in 2013. Mainland China, the European Union and Japan are the main providers of carbon inflows. Dominated by gaming service exports, total carbon outflows are equal to 6.48E+06 t in 2013, which is 2.6 times that of year 2000. Macao has avoided large amounts of local carbon emissions by net carbon emission imports, indicating that the decarbonization of the urban economy achieved by transferring carbon intensive industries to other places is a bias towards sustainability. Following the results, holistic energy conservation and carbon reduction policies are proposed for Macao from both the local and global perspective.