Study on calculation of carbon emission factors and embodied carbon emissions of iron-containing commodities in international trade of China

Embodied carbon emissions (ECE) of iron-containing commodities (ICC) in international trade are an important basis for effectively allocating both carbon emissions responsibility and emission quotas among countries. China is a major consumer of iron resources worldwide and the world's largest trader in ICC. Accurately calculating the ECE of ICC in China's international trade is of great significance to objectively evaluate China's carbon emissions responsibilities and to rationally allocate carbon emission quotas among countries. In this study, we verified the carbon emission factor for China's import and export of ICC and analyzed the ECE of ICC between China and other countries worldwide from 2010 to 2015. The results are as follows. (1) The ECE of China's export of ICC is higher than those of imported ICC. (2) In 2010–2015, the amount of iron materials in the import and export of China increased to 192 and 138 million tons, respectively. Most of the iron material imported by China is iron ore (about 90%), and more than 98% of China's exported iron material is iron-containing end products (IEPs) and rolled steel. (3) The ECE of China's imports of ICC decreased from 98 million tons in 2010 to 77 million tons in 2015 and consisted primarily of rolled steel and IEPs. The ECE of China's exports of ICC increased from 249 million tons in 2010 to 482 million tons in 2015 and consisted primarily of IEPs and rolled steel. (4) The ECE of China's exports of ICC are much larger than that the exports of ICC. The ECE of net exports of ICC, primarily to the United States, Vietnam, South Korea, and Indonesia, increased from 151 million tons in 2010 to 405 million tons in 2015. (5) The ECE of exports of ICC were approximately 4.7% of China's domestic carbon emissions (calculated using the production-based principle) in 2015. The total amount of China's domestic carbon emissions in the production-based principle is huge, but a large part is embodied in ICC exported to other countries worldwide. The shared responsibility principle (SRP) can better reflect the fairness and also contribute to the global participation of climate policy, which has the highest effectiveness. Therefore, calculation of carbon emissions using the SRP is a more objective assessment of China's carbon emissions responsibility, thus making the allocation of carbon credits among countries more fair and reasonable.