A high-resolution speleothem record of western equatorial Pacific rainfall: Implications for Holocene ENSO evolution
A high-resolution speleothem record of western equatorial Pacific rainfall: Implications for Holocene ENSO evolution
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DOI：
10.1016/j.epsl.2016.02.050
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发表时间：
2016-05-15
影响因子：
5.3
通讯作者：
Adkins, Jess F.
中科院分区：
文献类型：
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作者：
Chen, Sang;Hoffmann, Sharon S.;Adkins, Jess F.
厄尔尼诺-南方涛动（ENSO）是热带和亚热带气候年际变化的主要驱动力。尽管在理解驱动ENSO的海洋-大气反馈方面取得了实质性进展，但对其百年和更长时间尺度的行为知之甚少。来自湖泊、珊瑚、软体动物和深海沉积物的古气候记录普遍表明，全新世中期（4-6 kyr BP）的ENSO变化比全新世晚期（0- 4kyr BP）弱。然而，记录之间的差异排除了一个明确的时间轴全新世ENSO演变，因此，ENSO变率的具体气候强迫机制的属性。在这里，我们展示了马来西亚婆罗洲以次年度分辨率采样的U-Th测年洞穴沉积物的Delta O-18结果。婆罗洲降水的δ O-18是区域对流强度和降水量的一个强有力的代用指标，两者都直接受ENSO活动的影响。我们估计的石笋8180方差在ENSO期间（2-7年）显示，在全新世中期（3240-3380和5160-5230年BP）的年际变化显着减少，相对于晚全新世（2390-2590年BP）和全新世早期（6590-6730年BP）。因此，婆罗洲的结果是不一致的湖泊记录的ENSO从东赤道太平洋显示很少或没有ENSO变化在全新世早期。相反，我们的结果支持赤道太平洋中部和东部的珊瑚、软体动物和有孔虫记录，这些记录显示ENSO方差在全新世中期达到最小值。减少中全新世年际三角洲O-18在婆罗洲的变化与整体最小的平均三角洲O-18从3.5到5.5 kyr BP。持续的暖池对流往往会增强步行者环流在全新世中期，这可能有助于减少ENSO变化在这一时期。这一发现意味着，在婆罗洲的对流强度和年际变化是由耦合的海气动力，岁差的太阳强迫敏感。隔离的确切机制，驱动长期ENSO演变将需要额外的高分辨率古气候重建和进一步调查全新世热带气候演变耦合气候模式。(C)2016维耶B. V.版权所有。
The El Nino-Southern Oscillation (ENSO) is the primary driver of interannual climate variability in the tropics and subtropics. Despite substantial progress in understanding ocean-atmosphere feedbacks that drive ENSO today, relatively little is known about its behavior on centennial and longer timescales. Paleoclimate records from lakes, corals, molluscs and deep-sea sediments generally suggest that ENSO variability was weaker during the mid-Holocene (4-6 kyr BP) than the late Holocene (0-4 kyr BP). However, discrepancies amongst the records preclude a clear timeline of Holocene ENSO evolution and therefore the attribution of ENSO variability to specific climate forcing mechanisms. Here we present delta O-18 results from a U-Th dated speleothem in Malaysian Borneo sampled at sub-annual resolution. The delta O-18 of Borneo rainfall is a robust proxy of regional convective intensity and precipitation amount, both of which are directly influenced by ENSO activity. Our estimates of stalagmite 8180 variance at ENSO periods (2-7 yr) show a significant reduction in interannual variability during the mid Holocene (3240-3380 and 5160-5230 yr BP) relative to both the late Holocene (2390-2590 yr BP) and early Holocene (6590-6730 yr BP). The Borneo results are therefore inconsistent with lacustrine records of ENSO from the eastern equatorial Pacific that show little or no ENSO variance during the early Holocene. Instead, our results support coral, mollusc and foraminiferal records from the central and eastern equatorial Pacific that show a mid-Holocene minimum in ENSO variance. Reduced mid-Holocene interannual delta O-18 variability in Borneo coincides with an overall minimum in mean delta O-18 from 3.5 to 5.5 kyr BP. Persistent warm pool convection would tend to enhance the Walker circulation during the mid-Holocene, which likely contributed to reduced ENSO variance during this period. This finding implies that both convective intensity and interannual variability in Borneo are driven by coupled airsea dynamics that are sensitive to precessional insolation forcing. Isolating the exact mechanisms that drive long-term ENSO evolution will require additional high-resolution paleoclimatic reconstructions and further investigation of Holocene tropical climate evolution using coupled climate models. (C) 2016 vier B.V. All rights reserved.