Reduced El Nino-Southern Oscillation during the Last Glacial Maximum
Reduced El Nino-Southern Oscillation during the Last Glacial Maximum
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DOI：
10.1126/science.1258437
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发表时间：
2015-01-16
期刊：
影响因子：
56.9
通讯作者：
Polissar, Pratigya J.
中科院分区：
文献类型：
--
作者：
Ford, Heather L.;Ravelo, A. Christina;Polissar, Pratigya J.
厄尔尼诺-南方涛动（ENSO）是全球年际变率的一个主要来源，但其对气候变化的响应尚不确定。末次盛冰期（LGM）的古气候记录提供了对全球边界条件（冰盖范围、大气CO2分压）与今天不同时ENSO行为的深入了解。在这项工作中，我们利用单个浮游有孔虫壳的测量重建了赤道太平洋站点的LGM温度变化。赤道深层温跃层改变了东赤道冷舌的动力学，导致LGM期间ENSO变率较晚全新世有所降低。这些结果表明，ENSO并不像之前认为的那样与东西温度梯度直接相关。相反，赤道东太平洋的温跃层在ENSO对LGM气候的响应中发挥了决定性作用。
El Nino-Southern Oscillation (ENSO) is a major source of global interannual variability, but its response to climate change is uncertain. Paleoclimate records from the Last Glacial Maximum (LGM) provide insight into ENSO behavior when global boundary conditions (ice sheet extent, atmospheric partial pressure of CO2) were different from those today. In this work, we reconstruct LGM temperature variability at equatorial Pacific sites using measurements of individual planktonic foraminifera shells. A deep equatorial thermocline altered the dynamics in the eastern equatorial cold tongue, resulting in reduced ENSO variability during the LGM compared to the Late Holocene. These results suggest that ENSO was not tied directly to the east-west temperature gradient, as previously suggested. Rather, the thermocline of the eastern equatorial Pacific played a decisive role in the ENSO response to LGM climate.