“气候门”与20世纪增暖的千年历史地位之争

2009年哥本哈根世界气候大会召开前夕的“气候门”(climategate)事件，将科学界对过去千年温度变化的“曲棍球杆曲线”(hockey stick)之争推向顶点。介绍了这一争议的始末，并根据相关文献对这一争议中的两个关键问题“中世纪暖期与小冰期是否在全球广泛存在、20世纪是否为过去千年最暖”进行了综述。结果显示：尽管大尺度的地表温度重建结果存在不确定性，但随着近20年来全球代用资料的不断丰富和研究方法的改进，大尺度温度变化重建结果的不确定性逐步降低，争议各方的观点正在逐步接近。特别是最新的研究结果显示：虽然20世纪增暖迅速，温暖程度也很明显，但在过去千年中并不是空前的。

"Climategate" and the debate on historical significance of the 20th century warming in the last millennium

Abstract Climategate, which happened before 2009 UN Climate Change Conference at Copenhagen, have sharply intensified the debate within the scientific community on the so-called 'hockey stick' reconstruction of temperature variations over the last millennium. In this paper, a brief summary of the development of the debate is made and special attention is given to two key issues, namely, whether the Medieval Warm Period and the Little Ice Age existed on a global scale, and whether the 20th century was the warmest one in the last millennium. It's found that along with the uncertainties of large-scale temperature reconstructions being increasingly reduced with the update of proxy dataset and improvements of reconstruction methods during the last 20 years, a general consensus among scientists on the issues is beginning to emerge. Particularly, several latest large-scale temperature reconstructions showed that the 20th century warmth, no matter in amplitude or rate, was not unprecedented in the last millennium.