The European Union Emissions Trading System (EU ETS), the worlds largest cap-and-trade carbon market, is central to EU climate policy. This study analyzes its efficiency, price behavior, and market structure from 2010 to 2020. Using an AR-GARCH framework, we find pronounced price clustering and short-term return predictability, with 60.05 percent directional accuracy and a 70.78 percent hit rate within forecast intervals. Network analysis of inter-country transactions shows a concentrated structure dominated by a few registries that control most high-value flows. Country-specific log-log regressions of price on traded quantity reveal heterogeneous and sometimes positive elasticities exceeding unity, implying that trading volumes often rise with prices. These results point to persistent inefficiencies in the EU ETS, including partial predictability, asymmetric market power, and unconventional price-volume relationships, suggesting that while the system contributes to decarbonization, its trading dynamics and price formation remain imperfect.

翻译：欧盟排放交易体系（EU ETS）作为全球最大的总量控制与交易碳市场，是欧盟气候政策的核心。本研究分析了2010年至2020年间该体系的效率、价格行为和市场结构。采用AR-GARCH框架，我们发现显著的价格聚集现象和短期收益可预测性，其方向性预测准确率为60.05%，预测区间内的命中率达到70.78%。对跨国交易进行的网络分析显示，市场结构高度集中，少数登记处主导了大部分高价值交易流。针对各国家的价格与交易量对数回归分析表明，弹性系数存在异质性，部分情况下正向弹性超过1，这意味着交易量常随价格上涨而增加。这些结果表明欧盟排放交易体系存在持续的低效问题，包括部分可预测性、不对称的市场力量以及非常规的价格-成交量关系，表明尽管该系统有助于脱碳进程，但其交易动态和价格形成机制仍不完善。