Unlocking synergistic emission reduction in mega-urban agglomerations: a multi-objective input-output approach to inter-regional structural optimization

With the acceleration of urbanization and industrial agglomeration, air pollution has emerged as a severe challenge for economically intensive regions such as the Beijing-Tianjin-Hebei area, posing a significant threat to public health and constraining sustainable economic development. To address the shortcomings of existing research in analyzing the underlying imbalance in the coupling between industrial structure and the energy system, this study constructs an input-output multi-objective optimization model. This model integrates sectoral linkages, energy consumption, and emission factors into a unified framework, enabling the simultaneous quantification of interactions among multiple elements. Through a multi-objective multi-objective optimization mechanism, it facilitates trade-off analysis and pathway searching under multiple objectives, including economic growth and environmental constraints. It generates a set of Pareto optimal pathways and decomposes the emission reduction contributions of various structural adjustments. The findings reveal that there is inertia in the response of economic growth and environmental targets; the emission reduction effect of industrial restructuring becomes significant only when the weight assigned to environmental objectives exceeds a certain threshold. While industrial optimization can achieve a win-win situation for both the economy and the environment, in terms of emission reduction potential, the effects of transitioning to a cleaner energy structure and improving energy efficiency far surpass those achievable through industrial restructuring alone. The study recommends that air pollution control in the Beijing-Tianjin-Hebei region should strengthen the core position of energy structure optimization in top-level design, coordinating industrial transformation and energy efficiency improvements to achieve systematic optimization of both environmental and economic benefits.