Do collaboration and subsidies sustainably promote port-shipping emission reduction? An analysis of multi-games and system dynamics

Government environmental subsidies and port-shipping enterprise collaboration are common ways to promote carbon emission reduction. To analyze the long-term effects of collaboration and subsidies, game models based on decentralized and centralized decision-making are constructed: Stackelberg games led by either the port or the shipping enterprise, vertical integration, and Nash bargaining game. Then, by comprehensively analyzing government subsidy coefficients, corporate investment costs, and shippers’ low-carbon preferences, the collaborative model that maximizes both emission reduction effectiveness and industry profits is identified. On this basis, the game reaction function and system dynamics are combined to reflect the nonlinear complex feedback, in order to accurately analyze the port-shipping green transformation under dynamic effects of decision delay, technology update and subsidy decline. The findings reveal that the centralized decision-making model yields higher shipping decarbonization benefits than the decentralized model. Excessive subsidies may discourage independent innovation. Therefore, subsidies only play a short-term incentive role, while collaboration can promote the sustainable development of the port and shipping industry.