关键词: 碳交易, 碳减排技术, 寡头垄断, 市场势力

Abstract: The process of global warming has intensified since the 21st century. As a responsible developing country, China has shown a positive attitude in the process of coping with global warming, and made solemn commitments to the world to “peak carbon dioxide” by 2030 and “carbon neutrality” by 2060. The “double carbon” strategy has pointed out the direction for the development of our country's low-carbon economy, and the realization of the “double carbon” strategy needs to stimulate the motivation of enterprises to reduce emissions. As an important institutional arrangement for realizing a low-carbon economy, our country's national carbon trading market was formally established in 2021 after preliminary trials in seven provinces and cities including Beijing, Tianjin, Shanghai, Chongqing, Hubei, Guangdong and Shenzhen.This system attempts to make emission reduction technology an active behavior of enterprises through economic incentives and punishments, which can lay a solid micro foundation for the development of my country's low-carbon economy. At present, enterprises participating in carbon trading in our country often have the characteristics of oligopoly. Based on the competition of emission reduction technologies, carbon trading will break the old balance of market power of oligopoly enterprises. Analyzing the impact of carbon trading on the market power of oligopolistic enterprises, on the one hand, can gain insight into the changes in the industry competition pattern caused by the carbon trading system; on the other hand, it can find the key variables that affect the market power of enterprises under carbon trading can provide policies for improving the efficiency of carbon trading tool.
The paper argues that researching the decision-making behavior of oligopoly enterprises under carbon trading based on the Cournot model is not consistent with reality. The Stackberg model is more suitable for the study of the uneven characteristics of carbon emission reduction among enterprises. Based on the Stackelberg model, the paper theoretically analyzes the impact of carbon trading on the market power of oligopoly enterprises from the perspective of emission reduction technologies among oligopoly enterprises. The results show that the relative size of the initial carbon emission coefficient is a key variable affecting the market power of oligopoly enterprises, for the relative size of the initial carbon emission coefficient has different effects on the market power of enterprises with different maturity levels of carbon emission reduction technologies. When the emission reduction technology is immature, the greater the ratio of the initial carbon emission coefficient between the follower enterprise and the leading enterprise, the more carbon trading is conducive to the strengthening of the market power of the leading enterprise, and carbon trading will widen the difference in market power among enterprises. When the emission reduction technology is mature , the larger the ratio of the initial carbon emission coefficient of the follower firm to the leader firm, the more carbon trading is beneficial to the follower firm to enhance its market power, and carbon trading so as to narrow the difference in market power among oligopolistic firms.
The results of the paper indicate that in the process of carrying out carbon trading, we should fully consider the status quo of the emission reduction technology of oligopoly enterprises, and use the carbon emission coefficient as an anchor to guide oligopoly enterprises to carry out healthy competition. Thus, we can realize the relationship changes between leading enterprises and following enterprises' roles and market positions. Changes may prevent leading companies from forming a long-term monopoly, thereby improving market efficiency. While carbon trading has changed corporate behavior, it will also change the competitive landscape of the market. Under the carbon trading system, the empirical analysis of the market power changes caused by the emission reduction technology competition among oligopoly enterprises is a direction for further research in the future. The influence of linear market demand for products and the cost function form of carbon emission reduction technologies on the conclusion also needs further evaluation.

Key words: carbon trading, carbon emission reduction technology, oligopoly, market power