Chinese stalagmite δ18O controlled by changes in the Indian monsoon during a simulated Heinrich event
Chinese stalagmite δ18O controlled by changes in the Indian monsoon during a simulated Heinrich event
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DOI：
10.1038/ngeo1169
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发表时间：
2011-07-01
影响因子：
18.3
通讯作者：
Bitz, Cecilia M.
中科院分区：
文献类型：
--
作者：
Pausata, Francesco S. R.;Battisti, David S.;Bitz, Cecilia M.
印度和中国的碳酸盐洞穴沉积被认为记录了季风降水的强度，因为碳酸盐的δ O-18跟踪了降水的同位素特征。这些记录显示了整个上一个冰河时代的空间相干变化，并表明季风强度在被称为丹斯加德-奥施格事件的千年尺度气候变化期间和海因里希冷却事件期间发生了改变。在这里，我们使用一个数值气候模型与嵌入式氧同位素模型，以评估是什么原因造成的变化，降水的氧同位素签名在气候扰动，旨在模仿海因里希事件。我们的模拟表明，在北大西洋海冰范围的突然增加，在末次冰期导致冷却在北方半球，减少降水在印度盆地和减弱的印度季风。印度上空的降水同位素较重，输往中国的水汽同位素富集。我们的模型广泛地再现了丰富的三角洲O-18在北方印度和东亚明显的洞穴记录在海因里希事件。因此，我们得出结论，在三角洲O-18洞碳酸盐与海因里希事件的变化反映了印度，而不是东亚季风降水的强度变化。
Carbonate cave deposits in India and China are assumed to record the intensity of monsoon precipitation, because the delta O-18 of the carbonate tracks the isotopic signature of precipitation. These records show spatially coherent variability throughout the last ice age and suggest that monsoon strength was altered during the millennial-scale climate variations known as Dansgaard-Oeschger events and during the Heinrich cooling events. Here we use a numerical climate model with an embedded oxygen-isotope model to assess what caused the shifts in the oxygen-isotope signature of precipitation during a climate perturbation designed to mimic a Heinrich event. Our simulations show that a sudden increase in North Atlantic sea-ice extent during the last glacial period leads to cooling in the Northern Hemisphere, reduced precipitation over the Indian basin and weakening of the Indian monsoon. The precipitation is isotopically heavier over India and the water vapour exported to China is isotopically enriched. Our model broadly reproduces the enrichment of delta O-18 over Northern India and East Asia evident in speleothem records during Heinrich events. We therefore conclude that changes in the delta O-18 of cave carbonates associated with Heinrich events reflect changes in the intensity of Indian rather than East Asian monsoon precipitation.