The European Union Emissions Trading System (EU ETS), the world's first and largest cap-and-trade carbon market, is a cornerstone of EU climate policy. This study provides a comprehensive empirical analysis of the EU carbon market's efficiency, price dynamics, and structural network from 2010 to 2020. First, we identify significant price clustering and short-term return predictability using an AR-GARCH model, achieving around 60 percent directional accuracy and a 80 percent hit rate within forecasted confidence intervals. These observed patterns motivate a deeper exploration of market structure. Second, leveraging this insight, a weighted network analysis of inter-country transactions uncovers a concentrated market where a few registries dominate high-value flows and exert disproportionate influence. Finally, building upon the network findings, country-specific log-log regressions of price on traded quantity reveal heterogeneous and sometimes counter-intuitive elasticities; in several cases, positive elasticities exceed unity, indicating that trading volumes rise with prices, a deviation from conventional demand behavior that highlights potential inefficiencies driven by speculation, strategic behavior, or policy distortions. Collectively, these results point to persistent inefficiencies within the EU ETS, including partial predictability, asymmetric market power, and anomalous price-volume relationships, implying that while the system has driven decarbonization, its trading and pricing mechanisms remain imperfect.

翻译：欧洲联盟排放交易体系（EU ETS）是全球首个也是规模最大的总量控制与交易碳市场，是欧盟气候政策的基石。本研究对2010年至2020年间欧盟碳市场的效率、价格动态及结构性网络进行了全面的实证分析。首先，我们利用AR-GARCH模型识别出显著的价格聚集现象和短期回报可预测性，在预测置信区间内实现了约60%的方向准确率和80%的命中率。这些观测到的模式促使对市场结构进行更深入的探索。其次，基于这一洞察，对跨国交易进行加权网络分析，揭示了一个高度集中的市场，其中少数登记机构主导高价值流动并施加不成比例的影响。最后，基于网络分析结果，对价格与交易量进行国家级的对数-对数回归分析，显示出异质且有时反直觉的弹性；在多个案例中，正弹性超过1，表明交易量随价格上涨而增加，这偏离了常规需求行为，凸显出由投机、策略行为或政策扭曲导致的潜在低效率。综合来看，这些结果指向EU ETS持续存在的低效率问题，包括部分可预测性、不对称市场力量以及异常的价格-数量关系，意味着尽管该体系推动了脱碳进程，但其交易与定价机制仍不完善。