Baker P A, Rigsby C A, Seltzer G O, Fritz S C, Lowenstein T K, Bacher N P, Veliz C
Duke University, Division of Earth and Ocean Sciences, Durham, North Carolina 27708-0227, USA.
Nature. 2001 Feb 8;409(6821):698-701. doi: 10.1038/35055524.
Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the 'Walker' circulation). Although this area plays a key role in global climate cycles, little is known about South American climate history. Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes. We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales. Long-duration wet periods, such as the Last Glacial Maximum--marked in the drill core by continuous deposition of lacustrine sediments--appear to have occurred in phase with summer insolation maxima produced by the Earth's precessional cycle. Short-duration, millennial events correlate well with North Atlantic cold events, including Heinrich events 1 and 2, as well as the Younger Dryas episode. At both millennial and orbital timescales, cold sea surface temperatures in the high-latitude North Atlantic were coeval with wet conditions in tropical South America, suggesting a common forcing.
南美洲热带地区是赤道大气全球纬向翻转环流（通常称为“沃克”环流）的三个主要中心之一。尽管该地区在全球气候周期中起着关键作用，但人们对南美洲的气候历史知之甚少。在此，我们描述了位于热带安第斯山脉的玻利维亚高原乌尤尼盐沼的沉积物岩心和深钻的井下测井结果。我们证明，在过去5万年里，高原地区在轨道（2万年）和千年时间尺度上的有效湿度都发生了重要变化。长时间的湿润期，如末次盛冰期——在岩心中以湖相沉积物的连续沉积为标志——似乎与地球岁差周期产生的夏季日照最大值同步出现。短时间的千年事件与北大西洋寒冷事件密切相关，包括海因里希事件1和2以及新仙女木事件。在千年和轨道时间尺度上，北大西洋高纬度地区寒冷的海面温度与南美洲热带地区的湿润条件同时出现，这表明存在共同的驱动力。
