Abstract: Fossil fuel combustion not only emits CO₂ but also releases atmospheric pollutants such as SO₂. CO₂ and these pollutants share a common origin and process. Currently, the excessive emissions of greenhouse gases and atmospheric pollutants pose a significant challenge to the international community, a problem exacerbated by the increasingly severe global climate change. The synergistic governance of pollution reduction and carbon mitigation has gradually become a mainstream trend in environmental management. It is of great significance to comprehensively explore the synergistic effects of pollution reduction and carbon mitigation within China’s carbon market for advancing international environmental governance and China’s ecological civilization. Difference-In-Differences (DID) model to evaluate the impact of China’s carbon market on the synergistic governance of carbon emissions and atmospheric pollutants. Furthermore, it innovatively identifies the driving mechanisms of the synergistic emission reduction effect of China’s carbon market from the perspective of internal constraints within the carbon market, based on both constraint and market mechanisms. This provides a new perspective for analyzing the driving mechanisms of the carbon market’s synergistic emission reduction effect. Additionally, a mediation effect model is used to analyze the transmission pathways of carbon market policies, aiming to comprehensively dissect the synergistic emission reduction effect of China’s carbon market.
The innovations of this paper are as follows: (1)Introducing internal constraint factors of the carbon market and analyzing the driving mechanisms of the synergistic emission reduction effect of the carbon market from both constraint and market perspectives, so as to provide a new perspective on constraint mechanisms for analyzing the carbon market’s synergistic emission reduction effect. (2)Including both CO₂ and SO₂ in the same analytical framework, and using a multi-period DID model to comprehensively analyze the synergistic emission reduction effect and action pathway of carbon market policies. This paper quantitatively analyzes the impacts of market and constraint mechanisms on synergistic emission reduction effect, while also exploring the action pathway of these effects.
The research findings are: (1)The implementation of the carbon market has synergistic emission reduction effect, reducing CO₂ emissions while also lowering SO₂ emissions, with the experimental results passing a series of robustness tests. (2)The constraint mechanism is the driving force for achieving synergistic emission reduction effect in carbon market policies, while the market mechanism has not yet been effective. This paper dissects the driving mechanisms of the carbon market’s synergistic emission reduction effect from the perspectives of constraint and market mechanisms. The proxy variables for the constraint mechanisms derived from the carbon market’s institutional design all have passed significance tests, while those for the market mechanisms have not. (3)Mediation effect tests further reveal that carbon market policies can promote synergistic emission reduction effect by optimizing the energy structure, but the pathways of technological innovation and industrial structure have not been evident.
Based on the research conclusions, the following three policy recommendations are proposed to further enhance the role of China’s carbon market in synergistically controlling pollution and reducing carbon emissions: (1)Scientifically set benchmarks for total quota and penalty severity, and further enhance the incentivizing effects of market mechanisms such as carbon pricing and liquidity. Based on the conclusions of this paper, the current carbon market primarily achieves carbon and synergistic emission reduction effect through constraint mechanisms like total quota and penalty severity. Therefore, it is necessary to rigorously set these constraint mechanisms to ensure the carbon market’s effectiveness in reducing pollution and carbon emissions without overburdening market participants. The market mechanisms’ synergistic emission reduction effect has not yet been fully realized, which may require the introduction of financial instruments to invigorate the carbon market and enhance the incentivizing effects of mechanisms such as carbon pricing and liquidity. (2)Synergistic development of pollution reduction and carbon mitigation should focus on promoting energy transition as a fundamental starting point. This study finds that the current carbon market in China achieves collaborative emission reduction effect through optimizing energy structure. Therefore, emphasis should be placed on the role of energy transition in driving pollution reduction and carbon mitigation. Accelerating the promotion and use of clean energy and gradually reducing reliance on fossil fuels can effectively lower emissions of atmospheric pollutants and CO₂. Promoting energy transition not only aids environmental protection but also fosters sustainable economic development. (3)Establish a unified system for synergistic pollution reduction and carbon mitigation to advance the dual goals of carbon peaking, carbon neutrality, and ecological and environmental protection. A unified system can optimize resource allocation, avoid resource waste due to fragmented policies and lack of coordination among relevant departments, and maximize the effects of pollution reduction and carbon mitigation. Moreover, a unified system can improve policy implementation efficiency, facilitating the simultaneous advancement of the dual goals of carbon peaking, carbon neutrality, and ecological and environmental protection in terms of both time and space.

Key words: carbon trading policy, synergistic emission reduction effect, driving mechanism, action pathway, multi-period DID model

摘要： 温室气体与大气污染物的过度排放是国际社会共同面临的重大挑战,减污降碳协同治理已成为主流趋势,探讨中国碳市场的协同减排效应对国际环境治理和中国生态文明建设的推进具有重要意义。本文基于准自然实验方法评估中国碳市场对碳排放与大气污染物协同治理的影响;创新性地从碳市场内部约束性角度,基于约束机制和市场机制识别中国碳市场协同减排效应的驱动机制;进一步分析了中国碳市场政策协同减排效应的传导路径。本文全面剖析了中国碳市场的协同减排效应,研究结果表明,中国碳市场政策具有显著的协同减排效应,降低了试点地区的CO₂和SO₂排放,约束机制是实现协同减排的主要推手,市场机制的作用并未充分发挥;中国碳市场可以通过优化能源结构促进CO₂和SO₂减排,技术创新和产业结构路径并未显现。

关键词: 碳交易政策, 协同减排效应, 驱动机制, 作用路径, 多期双重差分