Input-output analysis of CO2 emissions embodied in trade: The effects of sector aggregation

Energy-related CO2 emissions embodied in international trade have been widely studied by researchers using the input-output analysis framework. These studies are often conducted at a specific level of sector aggregation and the choice made to a large extent is dictated by economic and energy data availability. We investigate analytically the possible effects of sector aggregation on the study results. We conduct empirical studies using the data of China and Singapore where energy-related CO2 emissions embodied in their exports are estimated at different levels of sector aggregation. A finding from the studies is that levels around 40 sectors appear to be sufficient to capture the overall share of emissions embodied in a country's exports. Another finding is that in approximating the "ideal" situation the hybrid data treatment approach produces better results than the uniformly distributed data treatment approach. Other findings and some recommendations are also presented.