Climate drivers for peatland palaeoclimate records
Climate drivers for peatland palaeoclimate records
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DOI：
10.1016/j.quascirev.2009.05.013
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发表时间：
2009-09-01
影响因子：
4
通讯作者：
Karofeld, Edgar
中科院分区：
文献类型：
--
作者：
Charman, Dan J.;Barber, Keith E.;Karofeld, Edgar
水文气候变率的重建是理解十年到千年时间尺度上自然气候变化的重要组成部分。泥炭地记录重建“沼泽表面湿度”（BSW）的变化，但目前还不清楚它是否是一个相对主导的降水或温度，推动了这些变化在全新世的时间尺度。以前，与仪器气候数据的相关性表明，降水是主要的控制。然而，最近的摇蚊推断7月温度记录表明，温度变化与全新世中晚期的BSW同步。本文提供了新的分析，这些数据来测试竞争的气候控制沼泽表面湿度的假设，并讨论了一些远驱动器的大规模空间格局的BSW变化。使用基于统计的年表和代理记录的不确定性估计，我们发现全新世夏季温度和BSW之间的相关性是合理的，但年表是不够精确的，以证明这一结论。与20世纪的观测结果相比，过去6000年来仅受温度影响的模拟夏季水分亏缺变化相对较小。仪器记录表明，夏季水分亏缺提供了最好的解释变量，测得的地下水位变化，更强烈的相关性比在爱沙尼亚和英国的温度与降水。我们的结论是，BSW主要是由降水驱动，加强了温度，这是负相关的降水，因此通常迫使夏季水分赤字在同一方向。在西欧，BSW的记录可能是由西风带的强度和位置的变化造成的，与大规模的北大西洋海洋和大气环流有关。(C)2009爱思唯尔有限公司保留所有权利。
Reconstruction of hydroclimate variability is an important part of understanding natural climate change on decadal to millennial timescales. Peatland records reconstruct 'bog surface wetness' (BSW) changes, but it is unclear whether it is a relative dominance of precipitation or temperature that has driven these variations over Holocene timescales. Previously, correlations with instrumental climate data implied that precipitation is the dominant control. However, a recent chironomid inferred July temperature record suggested temperature changes were synchronous with BSW over the mid-late Holocene. This paper provides new analyses of these data to test competing hypotheses of climate controls on bog surface wetness and discusses some of the distal drivers of large-scale spatial patterns of BSW change. Using statistically based estimates of uncertainty in chronologies and proxy records, we show a correlation between Holocene summer temperature and BSW is plausible, but that chronologies are insufficiently precise to demonstrate this conclusively. Simulated summer moisture deficit changes for the last 6000 years forced by temperature alone are relatively small compared with observations over the 20th century. Instrumental records show that summer moisture deficit provides the best explanatory variable for measured water table changes and is more strongly correlated with precipitation than with temperature in both Estonia and the UK. We conclude that BSW is driven primarily by precipitation, reinforced by temperature, which is negatively correlated with precipitation and therefore usually forces summer moisture deficit in the same direction. In western Europe, BSW records are likely to be forced by changes in the strength and location of westerlies, linked to large-scale North Atlantic ocean and atmospheric circulation. (C) 2009 Elsevier Ltd. All rights reserved.