Northern Hemisphere temperature patterns in the last 12 centuries
Northern Hemisphere temperature patterns in the last 12 centuries
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DOI：
10.5194/cp-8-227-2012
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发表时间：
2011-10
影响因子：
4.3
通讯作者：
F. Ljungqvist;P. Krusic;G. Brattström;H. Sundqvist
中科院分区：
文献类型：
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作者：
F. Ljungqvist;P. Krusic;G. Brattström;H. Sundqvist
我们利用一个史无前例的温度敏感替代记录网络，分析了过去12个世纪北半球陆地地区百年时间尺度上温度变化的时空模式。从9世纪到11世纪，观测到了地理上广泛的正温度异常，其范围和强度与20世纪的平均水平相似。从16世纪到18世纪，普遍的负异常占主导地位。虽然我们发现20世纪变暖的幅度和空间范围在过去12个世纪的自然变率范围内，但我们也发现，从19世纪到20世纪的升温速度在过去1200年的背景下是前所未有的。从19世纪到20世纪，北半球气温的正变化显然是过去12个世纪中连续两个世纪中最大的。这些结果即使在各种稳健性测试中删除了相当数量的代理后仍保持稳健，表明代理的选择对本研究的整体结论没有特别的影响。
We analyse the spatio-temporal patterns of temperature variability over Northern Hemisphere land areas, on centennial time-scales, for the last 12 centuries using an unprecedentedly large network of temperature-sensitive proxy records. Geographically widespread positive temperature anomalies are observed from the 9th to 11th centuries, similar in extent and magnitude to the 20th century mean. A dominance of widespread negative anomalies is observed from the 16th to 18th centuries. Though we find the amplitude and spatial extent of the 20th century warming is within the range of natural variability over the last 12 centuries, we also find that the rate of warming from the 19th to the 20th century is unprecedented in the context of the last 1200 yr. The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. These results remain robust even after removing a significant number of proxies in various tests of robustness showing that the choice of proxies has no particular influence on the overall conclusions of this study.