Decadal warming events extended into central North America during the last glacial period
Decadal warming events extended into central North America during the last glacial period
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DOI：
10.1038/s41561-023-01132-3
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发表时间：
2023-03
影响因子：
18.3
通讯作者：
C. Batchelor;S. Marcott;I. Orland;F. He;R. Edwards
中科院分区：
文献类型：
--
作者：
C. Batchelor;S. Marcott;I. Orland;F. He;R. Edwards
末次冰期高纬度突然变暖--Dansgaard-Oeschger（DO）事件--与低纬度气候快速变化之间的联系揭示了海洋-大气系统中的半球间遥相关。DO事件和气候变率之间的联系，在中纬度，中大陆设置仍然知之甚少，特别是在北美，有足够的时间分辨率的气候档案稀缺。在这里，我们研究了一个洞穴沉积物，从约7万至5万年前（ka）在威斯康星州（美国）和联合收割机结合其生长带的荧光成像与年度分辨率的氧同位素（δ 18 O）记录。在北格陵兰冰芯项目记录的17-14年溶解氧事件中，在61-55 ka之间发生了8次大的（2.0-3.0‰）负δ 18 O漂移，每次都在<10个年增长带中开始。虽然年龄模型不允许这些δ 18 O漂移与特定的DO事件相匹配，但其幅度和快速发作支持可信的联系。同位素气候模拟表明，突然的溶解氧变暖将增加研究区域年降水的δ 18 O，并证实在<10年内变暖>10 °C是产生观测到的负δ 18 O偏移所必需的。我们的研究结果在北美中部的扩张突然DO变暖的环境，气候和冰盖动态的影响。
The connection between abrupt high-latitude warming during the last glacial period—Dansgaard–Oeschger (DO) events—and rapid climate changes at lower latitudes has revealed inter-hemispheric teleconnections in the ocean–atmosphere system. Links between DO events and climate variability in mid-latitude, mid-continent settings remain, however, poorly understood, especially in North America where climate archives with sufficient time resolution are scarce. Here we examine a speleothem that grew from ~70–50 thousand years ago (ka) in Wisconsin (United States) and combine fluorescent imaging of its growth banding with an annual-resolution oxygen isotope (δ18O) record. Eight large (2.0–3.0‰) negative δ18O excursions, each with an onset in <10 annual growth bands, occur between 61–55 ka, when DO events 17–14 are recorded in the ice core of the North Greenland Ice Core Project. Although the age model does not allow these δ18O excursions to be matched to specific DO events, their magnitude and rapid onset support a credible link. Isotope-enabled climate simulations suggest that abrupt DO warming would increase the δ18O of annual precipitation in the study area and corroborate that warming of >10 °C in <10 years is thus required to produce the observed negative δ18O excursions. Our findings of expansive abrupt DO warming in central North America has implications for environmental, climate and ice sheet dynamics.