This study investigates the heterogeneity and driving factors of carbon emission reduction in developed countries, providing insights for formulating carbon neutrality strategies and plans in China. Firstly, typical developed countries worldwide are categorized into four modes: high energy consumption–high emissions, high energy consumption–low emissions, low energy consumption–low emissions and low energy consumption–high emissions, based on the “per capita energy consumption–emission intensity” classification method. Secondly, the LMDI decomposition model is employed to calculate the carbon emission-reduction driving effects of each mode, thereby analyzing the evolution path of carbon emissions. Finally, carbon emission-reduction policy recommendations are proposed based on the current situation of provincial carbon emissions in China. The research findings are as follows: (1) Carbon emissions in developed countries follow the Environmental Kuznets Curve (EKC) law, exhibiting an inverted U-shaped trajectory. In the per capita GDP range of USD 12,000–20,000, carbon emissions in most countries have reached or are close to their peak, with per capita carbon emissions in different modes decreasing and tending towards a level of 4000 kg/person. (2) There is heterogeneity in the EKC of carbon emissions in developed countries, which can be divided into technological, structural, comprehensive and clean types based on differences in emission-reduction factors. The trajectories of carbon emissions in most developed countries follow a clean path, while those in newly developed countries are constrained by environmental pressures and are expected to be between mixed and structural types before the emission peak, and tend towards a clean type after the peak. (3) Energy clean-up is the most direct and efficient method for carbon emission reduction, which can significantly and efficiently achieve carbon emission reduction. Industrial restructuring and technological progress play a significant role in suppressing carbon emissions. Policy recommendations are proposed as follows: first, reduce the proportion of fossil energy and increase energy cleanliness; second, promote industrial restructuring to reduce energy dependence; third, enhance production technology and improve energy-utilization efficiency; fourth, increase technological breakthroughs to support low-carbon transformation; fifth, correctly recognize the differences among provinces in China and formulate differentiated carbon emission-reduction policies.

This study aims to investigate the impact of China’s Free Trade Zones (FTZs) on carbon emissions and their underlying mechanisms, addressing the following research questions: (1) Do FTZs significantly affect carbon emissions? (2) Are there spatial differences in the carbon reduction effects of these FTZs? (3) What mechanisms underlie the carbon reduction effects of FTZs? (4) Are there moderating factors that influence the effectiveness of these FTZs? Using a difference-in-differences (DID) model, this study measures the net effect of FTZ implementation on carbon emissions in 21 pilot provinces and cities in China. Additionally, it examines whether the FTZ effect shows mediating effects and introduces interaction terms to test for moderating effects. The findings are as follows: (1) The regression coefficient of FTZs on carbon emissions is −0.162, indicating that FTZs significantly reduce carbon emissions. (2) The effect of FTZs on carbon emissions varies significantly across regions, with the carbon reduction effects increasing progressively from the eastern to the central and western regions. (3) The mediating effect indicates that FTZs reduce carbon emissions by enhancing technological levels. (4) Industrial structure has a significant moderating role in the carbon emission effects of FTZs, with optimizing the industrial structure helping to suppress the increase in carbon emissions. Based on these findings, the study suggests accelerating the replication and promotion of advanced FTZ practices, strengthening carbon reduction policies driven by technological progress, and leveraging regional industrial layout adjustments to facilitate overall industrial structure upgrading.