A major advance of tropical Andean glaciers during the Antarctic cold reversal
A major advance of tropical Andean glaciers during the Antarctic cold reversal
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DOI：
10.1038/nature13546
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发表时间：
2014-09-11
期刊：
影响因子：
64.8
通讯作者：
Otto-Bliesner, B. L.
中科院分区：
文献类型：
--
作者：
Jomelli, V.;Favier, V.;Otto-Bliesner, B. L.
新仙女木stadial，一个寒冷的事件，跨越12，800至11，500年前，在最后一次冰川消退期间，被认为是与热带安第斯山脉最后一次主要的冰川再前进相吻合（1）。这种解释主要依赖于冰川沉积物的宇宙射线暴露年代测定。然而，最近的研究已经确定了宇宙成因Be-10和He-3的新生产率，这使得有必要更新该地区的所有年表（1，5 -15），并修改我们对冰冻圈对气候变化的反应的理解。在这里，我们提出了一个新的Be-10冰碛在哥伦比亚的年表显示，在北方热带安第斯山脉的冰川扩大到更大的程度在南极寒冷逆转（14,500年至12,900年前）比在新仙女木。在整个热带安第斯山脉的所有Be-10和He-3冰碛年龄的均质化年表的基础上，我们表明，这种行为是常见的北方和南部的热带安第斯山脉。一个耦合的全球气候模式的瞬态模拟表明，共同的冰川行为的结果，大西洋纬向翻转环流的变化叠加在大气中的二氧化碳浓度的冰消增加。在南极冷逆转期间，冰川的推进主要是对南半球大部分地区寒冷的海面温度的反应。然而，在新仙女木期，北方热带安第斯山脉冰川退缩，这是由于降水减少和大西洋纬向翻转环流减弱引发的陆面反馈导致区域突然变暖。相反，在南部热带安第斯山脉的新仙女木期，冰川退缩是逐渐变暖的结果，可能是受大气二氧化碳增加的影响。考虑到来自中纬度安第斯冰川的证据（16），我们的研究结果表明，在南极寒冷逆转中，冰川对寒冷条件的共同反应超过了新仙女木。
The Younger Dryas stadial, a cold event spanning 12,800 to 11,500 years ago, during the last deglaciation, is thought to coincide with the last major glacial re-advance in the tropical Andes(1). This interpretation relies mainly on cosmic-ray exposure dating of glacial deposits. Recent studies, however, have established new production rates' for cosmogenic Be-10 and He-3, which make it necessary to update all chronologies in this region(1,5-15) and revise our understanding of cryospheric responses to climate variability. Here we present a new Be-10 moraine chronology in Colombia showing that glaciers in the northern tropical Andes expanded to a larger extent during the Antarctic cold reversal (14,500 to 12,900 years ago) than during the Younger Dryas. On the basis of a homogenized chronology of all Be-10 and He-3 moraine ages across the tropical Andes, we show that this behaviour was common to the northern and southern tropical Andes. Transient simulations with a coupled global climate model suggest that the common glacier behaviour was the result of Atlantic meridional overturning circulation variability superimposed on a deglacial increase in the atmospheric carbon dioxide concentration. During the Antarctic cold reversal, glaciers advanced primarily in response to cold sea surface temperatures over much of the Southern Hemisphere. During the Younger Dryas, however, northern tropical Andes glaciers retreated owing to abrupt regional warming in response to reduced precipitation and land-surface feedbacks triggered by a weakened Atlantic meridional overturning circulation. Conversely, glacier retreat during the Younger Dryas in the southern tropical Andes occurred as a result of progressive warming, probably influenced by an increase in atmospheric carbon dioxide. Considered with evidence from mid-latitude Andean glaciers(16), our results argue for a common glacier response to cold conditions in the Antarctic cold reversal exceeding that of the Younger Dryas.