Abrupt Holocene climate change and potential response to solar forcing in western Canada
Abrupt Holocene climate change and potential response to solar forcing in western Canada
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DOI：
10.1016/j.quascirev.2011.03.003
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发表时间：
2011-05-01
影响因子：
4
通讯作者：
Hu, Feng Sheng
中科院分区：
文献类型：
--
作者：
Gavin, Daniel G.;Henderson, Andrew C. G.;Hu, Feng Sheng
全新世期间的几次气候突变事件，包括广泛记录的距今82000年的涛动，都归因于北大西洋温盐环流的变化。还提出了其他机制，如大气环流、冰盖动力学和太阳辐照度的影响之间的相互作用，以解释突发气候事件，但证据仍然难以获得。本研究提出了对不列颠哥伦比亚省埃莉诺湖全新世沉积物的多代理分析证据。生物硅（BSi）丰度的年代际分辨率记录支持了来自同一岩心的硅藻和花粉组合的变化以及与现有区域气候记录的相关性的气候推断。BSi记录揭示了10.2 ka、9.3 ka和8.5 ka的突变和持续的气候变化，后两者与劳伦泰德冰盖的主要崩塌同时发生。记录还揭示了8.2 ka的短期冷却，这与8.5 ka事件不同，在量级上与其他几次晚全新世冷却相似。BSi与太阳辐照度指数相关（r = 0.43 ~ 0.61），但与太阳直接强迫的相关性在符号上相反，在8 ka后减弱。导致全新世早期气候突变和持续变化的可能机制包括：1)冰和前冰湖范围的突然消失，引起大气环流经向结构的转变；2)太阳极小期和厄尔尼诺现象之间的可能联系，与不列颠哥伦比亚省内陆温暖的春季温度有关；3)太阳辐照度变率对极地急流位置的影响。可能是通过对冰川反气旋强度的影响。(C) 2011 Elsevier Ltd.版权所有。
Several abrupt climate events during the Holocene, including the widely documented oscillation at 8.2 thousand years before present (ka), are attributed to changes in the North Atlantic thermohaline circulation. Additional mechanisms, such as interactions between atmospheric circulation, ice-sheet dynamics, and the influence of solar irradiance, also have been proposed to explain abrupt climatic events, but evidence remains elusive. This study presents evidence from multi-proxy analyses on the Holocene sediments of Eleanor Lake, interior British Columbia. Climatic inferences from our decadal-resolution record of biogenic silica (BSi) abundance are supported by changes in diatom and pollen assemblages from the same core and correlations with existing regional climate records. The BSi record reveals abrupt and persistent climatic shifts at 10.2, 9.3, and 8.5 ka, the latter two of which are coeval with major collapses of the Laurentide Ice Sheet. The record also reveals a short-term cooling at 8.2 ka that is distinct from the 8.5 ka event and similar in magnitude to several other late-Holocene coolings. BSi is correlated with solar-irradiance indices (r = 0.43-0.61), but the correlation is opposite in sign to that expected from direct solar forcing and weakens after 8 ka. Possible mechanisms causing the abrupt and persistent climate changes of the early Holocene include 1) sudden losses of ice and proglacial lake extent, causing a shift in the meridional structure of atmospheric circulation, 2) a possible link between solar minima and El Nino-like conditions that are correlated with warm spring temperature in interior British Columbia, and 3) the influence of solar irradiance variability on the position of the polar jet, possibly via effects on the strength of the glacial anticyclone. (C) 2011 Elsevier Ltd. All rights reserved.