On the long-term context for late twentieth century warming
On the long-term context for late twentieth century warming
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DOI：
10.1029/2005jd006352
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发表时间：
2006-02-07
影响因子：
4.4
通讯作者：
Jacoby, G
中科院分区：
文献类型：
--
作者：
D'Arrigo, R;Wilson, R;Jacoby, G
[1]以前基于树木年轮的北方半球温度重建描绘了“中世纪温暖期”（MWP），“小冰期”（LIA）和现在之间的变化幅度范围。我们描述了一个新的重建，开发使用很大程度上不同的方法和额外的新数据相比，以前的努力。与早期的研究不同，我们量化了更传统的（STD）和区域曲线标准化（RCS）方法之间的差异，得出的结论是RCS是上级保留低频趋势。北美大陆与欧亚大陆RCS系列在合并到半球尺度之前发展得惊人地一致，这表明共同的强迫，尽管有明显的偏差（例如，例如，在一个实施例中，世纪至16世纪）。结果显示明确的MWP（温暖），LIA（凉爽）和最近（温暖）发作。对RCS重建的直接解释表明，MWP温度比20世纪后期低近0.7摄氏度，从最冷（1600 - 1609年）到最热（1937 - 1946年）的几十年之间的幅度差异为1.14摄氏度。然而，我们建议谨慎对待这种分析。尽管我们得出结论，如其他地方所发现的那样，最近的变暖相对于过去一千年的自然波动是相当大的，但我们也注意到，由于MWP的空间异质性，以及它在不同地区的不同时间，目前的古气候方法可能会相对于20世纪变暖，表达了一个更同质的全球“指纹”，“平坦化”估计这一时期。“因此，我们强调，目前可用的古气候重建不足以在半球尺度上对MWP相对于当前人类活动时期的温暖进行具体的推断，并且这种比较仍然只能在局部/区域尺度上进行。
[1] Previous tree-ring-based Northern Hemisphere temperature reconstructions portray a varying amplitude range between the "Medieval Warm Period'' (MWP), "Little Ice Age'' (LIA) and present. We describe a new reconstruction, developed using largely different methodologies and additional new data compared to previous efforts. Unlike earlier studies, we quantify differences between more traditional ( STD) and Regional Curve Standardization (RCS) methodologies, concluding that RCS is superior for retention of low-frequency trends. Continental North American versus Eurasian RCS series developed prior to merging to the hemispheric scale cohere surprisingly well, suggesting common forcing, although there are notable deviations ( e. g., fifteenth to sixteenth century). Results indicate clear MWP ( warm), LIA ( cool), and recent ( warm) episodes. Direct interpretation of the RCS reconstruction suggests that MWP temperatures were nearly 0.7 degrees C cooler than in the late twentieth century, with an amplitude difference of 1.14 degrees C from the coldest ( 1600 - 1609) to warmest ( 1937 - 1946) decades. However, we advise caution with this analysis. Although we conclude, as found elsewhere, that recent warming has been substantial relative to natural fluctuations of the past millennium, we also note that owing to the spatially heterogeneous nature of the MWP, and its different timing within different regions, present palaeoclimatic methodologies will likely "flatten out'' estimates for this period relative to twentieth century warming, which expresses a more homogenous global "fingerprint.'' Therefore we stress that presently available paleoclimatic reconstructions are inadequate for making specific inferences, at hemispheric scales, about MWP warmth relative to the present anthropogenic period and that such comparisons can only still be made at the local/regional scale.