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Lacustrine leaf wax hydrogen isotopes indicate strong regional climate feedbacks in Beringia since the last ice age
Quaternary Science Reviews ( IF 4 ) Pub Date : 2021-08-21 , DOI: 10.1016/j.quascirev.2021.107130
W.C. Daniels 1, 2 , J.M. Russell 1 , C. Morrill 3, 4 , W.M. Longo 1 , A.E. Giblin 2 , P. Holland-Stergar 1 , J.M. Welker 5, 6 , X. Wen 7 , A. Hu 8 , Y. Huang 1
Affiliation  

The Late-Quaternary climate of Beringia remains unresolved despite the region's role in modulating glacial-interglacial climate and as the likely conduit for human dispersal into the Americas. Here, we investigate Beringian temperature change using an ∼32,000-year lacustrine record of leaf wax hydrogen isotope ratios (δ2Hwax) from Arctic Alaska. Based on Monte Carlo iterations accounting for multiple sources of uncertainty, the reconstructed summertime temperatures were ∼3 °C colder (range: −8 to +3 °C) during the Last Glacial Maximum (LGM; 21-25 ka) than the pre-industrial era (PI; 2–0.1 ka). This ice-age summer cooling is substantially smaller than in other parts of the Arctic, reflecting altered atmospheric circulation and increased continentality which weakened glacial cooling in the region. Deglacial warming was punctuated by abrupt events that are largely synchronous with events seen in Greenland ice cores that originate in the North Atlantic but which are also controlled locally, such as by the opening of the Bering Strait between 13.4 and 11 ka. Our reconstruction, together with climate modeling experiments, indicates that Beringia responds more strongly to North Atlantic freshwater forcing under modern-day, open-Bering Strait conditions than under glacial conditions. Furthermore, a 2 °C increase (Monte Carlo range: −1 to +5 °C) over the anthropogenic era reverses a 6 °C decline (Monte Carlo range: −10 to 0 °C) through the Holocene, indicating that recent warming in Arctic Alaska has not surpassed peak Holocene summer warmth.



中文翻译:

湖泊叶蜡氢同位素表明自上次冰河时代以来白令岛强烈的区域气候反馈

尽管该地区在调节冰期-间冰期气候方面发挥了作用,并且可能是人类向美洲扩散的渠道,但该地区的晚第四纪气候仍未得到解决。在这里,我们使用约 32,000 年的叶蜡氢同位素比(δ 2 H) 来自北极阿拉斯加。基于考虑到多种不确定性来源的蒙特卡罗迭代,重建的夏季温度在末次盛冰期(LGM;21-25 ka)期间比前次冰期低约 3°C(范围:-8 至 +3°C)。工业时代(PI;2-0.1 ka)。这种冰河时代夏季降温幅度远小于北极其他地区,这反映了大气环流的改变和大陆性的增加,从而削弱了该地区的冰川降温。冰消期变暖被突然事件打断,这些事件与起源于北大西洋的格陵兰冰芯中的事件基本同步,但也受到局部控制,例如 13.4 至 11 ka 之间白令海峡的开放。我们的重建,连同气候模拟实验,表明在现代开放的白令海峡条件下,白令岛对北大西洋淡水强迫的反应比在冰川条件下更强烈。此外,人类活动时代升高 2 °C(蒙特卡罗范围:-1 至 +5 °C)会逆转全新世期间 6 °C 的下降(蒙特卡罗范围:-10 至 0 °C),表明最近的变暖在北极阿拉斯加还没有超过全新世夏季温暖的高峰。

更新日期:2021-08-21
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