Tracing urban carbon footprints differentiating supply chain complexity: A metropolis case

More complicated linkages between sectors are enhancing supply chain complexity. How carbon footprints (CFs) transfer through simple and complex supply chain paths (SSCPs and CSCPs) (differentiated according to production layers covered) and evolve driven by socioeconomic effects remain elusive. Targeting Shanghai with a population larger than 20 million and pillar industries including services, transportation, communication electronics, we identified the key supply chain paths for CFs to uncover their evolutionary characteristics and investigated the contributions of major socioeconomic drivers including supply chain complexity to CFs changes during 2007–2017 based on structural path analysis and structural decomposition analysis. Results indicate that total CFs increased from 165.0 to 191.2 Mt-CO2, then decreased to 177.4 Mt-CO2. CFs of CSCPs kept decreasing, accompanied by the declining proportion in total CFs (3.1%–1.5%). The downstream sectors of Transportation and Metals Smelting and Pressing driven by export were most observable in the supply chain. For SSCPs, the most important negative driver of CFs turned from emission intensity to industrial structure. The transition of supply chain complexity favored to CFs reduction in CSCPs, especially for those associated with export. The findings provide decision-makers with reference to sounder urban supply chain management for pertinent carbon emission control.