Lacustrine leaf wax hydrogen isotopes indicate strong regional climate feedbacks in Beringia since the last ice age
Lacustrine leaf wax hydrogen isotopes indicate strong regional climate feedbacks in Beringia since the last ice age
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DOI：
10.1016/j.quascirev.2021.107130
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发表时间：
2021-10
影响因子：
4
通讯作者：
W. Daniels;J. Russell;C. Morrill;W. Longo;A. Giblin;P. Holland-Stergar;J. Welker;X. Wen;A. Hu;Y. Huang
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作者：
W. Daniels;J. Russell;C. Morrill;W. Longo;A. Giblin;P. Holland-Stergar;J. Welker;X. Wen;A. Hu;Y. Huang
尽管白令吉亚地区在调节冰川-间冰期气候方面发挥着重要作用，并可能成为人类向美洲扩散的通道，但该地区的晚第四纪气候仍未得到解决。在这里，我们研究白令纪的温度变化，使用132000年的湖泊记录的叶蜡氢同位素比值（δ 2 Hwax）从北极阿拉斯加。基于蒙特卡罗迭代法，考虑到多种不确定性来源，重建的夏季温度在末次盛冰期（LGM; 21-25 ka）比前工业时代（PI; 2-0.1 ka）低0.3 °C（范围：-8至+3 °C）。这种冰河时期的夏季冷却比北极其他地区要小得多，反映了大气环流的改变和大陆性的增加，这削弱了该地区的冰川冷却。冰消期变暖被突发事件打断，这些事件与格陵兰冰芯中的事件基本同步，格陵兰冰芯起源于北大西洋，但也受到局部控制，例如13.4和11 ka之间白令海峡的开放。我们的重建，连同气候模拟实验，表明白令海峡响应更强烈的北大西洋淡水强迫下现代，开放的白令海峡条件下，比冰川条件下。此外，在人类活动时期增加2 °C（蒙特卡洛范围：-1至+5 °C），在全新世逆转了6 °C的下降（蒙特卡洛范围：-10至0 °C），表明阿拉斯加北极最近的变暖没有超过全新世夏季的峰值。
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.