Holocene changes in eastern tropical Pacific climate inferred from a Galapagos lake sediment record
Holocene changes in eastern tropical Pacific climate inferred from a Galapagos lake sediment record
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DOI：
10.1016/j.quascirev.2008.02.015
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发表时间：
2008-06-01
影响因子：
4
通讯作者：
Steinitz-Kannan, Miriam
中科院分区：
文献类型：
--
作者：
Conroy, Jessica L.;Overpeck, Jonathan T.;Steinitz-Kannan, Miriam
来自热带太平洋的古气候记录表明，全新世早期到中期是厄尔尼诺/南方涛动（ENSO）变率降低的时期，在过去几千年的某个时间过渡到现代，ENSO频率增加。然而，由于许多ENSO代理的不连续性和/或粗糙的分辨率，以及以前公布的记录之间缺乏一致性，这种转变的性质和时间仍然不确定。一个新的，连续的，气候记录从厄尔尼诺Junco火山口湖在Galdpagos群岛揭示了几个突然变化的湖泊水位和降水通过全新世。水文气候模型模拟表明，厄尔尼诺Junco湖的水位敏感地响应与厄尔尼诺事件相关的降水量增加，在湿厄尔尼诺事件上升，并在干旱期间下降。从El Junco沉积物岩心获得的粒度数据表明，过去湖泊水位的变化可能与季节性降水和厄尔尼诺/南方涛动频率的变化有关。粒度数据表明，在9000+/-120 cal年BP之前和4200+/-130 cal年BR之后，降水强度增加，以及在3200+/-160和2000+/-100 cal年BP降水的两步增加。最大全新世降水和推断ENSO变率发生在2000+/-100和1500+/-70 cal年BP之间，在同一时期，其他六个独立的代理记录表明更高的ENSO频率和更长，更强的厄尔尼诺事件。减少沉积物碳/氮（C/N）比在埃尔Junco沉积物表明上升的湖泊水位从全新世早期到现在，证实了粒度数据。在4200+/-130 cal年BP和2000 +/- 100 cal年BP的降水量增加与西南亚和东亚季风强度的下降相一致，表明热带太平洋气候和亚洲季风在全新世的百年至千年时间尺度上是相互关联的系统。减弱的趋势，在亚洲季风和潮湿的条件下，在厄尔尼诺Junco的趋势也一致的趋势推断从Cariaco盆地沉积物代理从中全新世到现在，热带辐合带（ITCZ）的迁移可能会影响水文变化在热带太平洋东部和亚洲季风地区在全新世。(C)2008爱思唯尔有限公司保留所有权利。
Paleoclimate records from the tropical Pacific suggest the early to mid-Holocene was a period of reduced El Nino/Southern Oscillation (ENSO) variability, with a transition to modern, increased ENSO frequency occurring some time in the last few thousand years. However, the nature and timing of this shift remains uncertain due to the discontinuous nature and/or coarse resolution of many ENSO proxies, as well as a lack of agreement between previously published records. A new, continuous, climate record from El Junco Crater Lake in the Galdpagos Islands reveals several abrupt changes in lake level and precipitation through the Holocene. Hydroclimatic model simulations suggest that El Junco lake level responds sensitively to increases in precipitation associated with El Nino events, rising during wet El Nino events and falling during the intervening dry periods. Grain size data from El Junco sediment cores indicate past lake level variability, likely associated with changing seasonal precipitation and ENSO frequency. The grain size data suggest increased precipitation intensity prior to 9000+/-120 cal years BP, and after 4200+/-130 cal years BR as well as a two-step increase in precipitation at 3200+/-160 and 2000+/-100 cal years BP. Maximum Holocene precipitation and inferred ENSO variability occurred between 2000+/-100 and 1500+/-70 cal years BP, during the same period that six other independent proxy records suggest higher ENSO frequency and longer, stronger El Nino events. Decreasing sediment carbon/nitrogen (C/N) ratios in El Junco sediments indicate rising lake levels from the early Holocene to present, corroborating the grain size data. The inferred increase in precipitation at 4200+/-130 cal years BP and at 2000 +/- 100 cal years BP coincides with decreasing Southwest Asian and East Asian Monsoon intensity, suggesting tropical Pacific climate and the Asian monsoon were interconnected systems at centennial to millennial timescales during the Holocene. A weakening trend in the Asian monsoon and the trend toward wetter conditions at El Junco also coincide with a trend toward cooler and drier conditions inferred from Cariaco Basin sediment proxies from the mid-Holocene to present, suggesting the migration of the Intertropical Convergence Zone (ITCZ) likely influenced hydrological changes in both the eastern tropical Pacific and the Asian Monsoon region during the Holocene. (C) 2008 Elsevier Ltd. All rights reserved.