A new study from Beijing Normal University, published in ENGINEERING Environment, breaks down how four Chinese megacities (Beijing, Tianjin, Shanghai, and Chongqing) moved toward carbon emission peaking between 2007 and 2017. The research uses a multi-regional input-output framework to separate the effects of energy intensity, energy structure, industrial transfer, and industrial upgrading. It finds that early emission cuts came mostly from energy efficiency gains, but those gains eventually plateaued. After that, cleaner energy and industrial restructuring became necessary to keep emissions falling. The study also highlights a problem with industrial transfer: moving heavy industry out of a city can make that city's emissions look better on paper without actually reducing global emissions. The authors argue that carbon governance should follow the full supply chain, not just city boundaries. For policymakers, the takeaway is that carbon peaking is not a single event but a staged process. Cities still early in the transition should focus on efficiency first. Those hitting diminishing returns need to shift to cleaner energy and deeper industrial upgrades. The framework is transferable to other urban centers facing similar decarbonization challenges.
