文章基本信息

标题：Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
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作者：Louise C. Sime ; Peter O. Hopcroft ; Rachael H. Rhodes 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：10
页码：4099-4104
DOI：10.1073/pnas.1807261116
出版社：The National Academy of Sciences of the United States of America
摘要：Greenland ice cores provide excellent evidence of past abrupt climate changes. However, there is no universally accepted theory of how and why these Dansgaard–Oeschger (DO) events occur. Several mechanisms have been proposed to explain DO events, including sea ice, ice shelf buildup, ice sheets, atmospheric circulation, and meltwater changes. DO event temperature reconstructions depend on the stable water isotope ( δ 18 O) and nitrogen isotope measurements from Greenland ice cores: interpretation of these measurements holds the key to understanding the nature of DO events. Here, we demonstrate the primary importance of sea ice as a control on Greenland ice core δ 18 O: 95% of the variability in δ 18 O in southern Greenland is explained by DO event sea ice changes. Our suite of DO events, simulated using a general circulation model, accurately captures the amplitude of δ 18 O enrichment during the abrupt DO event onsets. Simulated geographical variability is broadly consistent with available ice core evidence. We find an hitherto unknown sensitivity of the δ 18 O paleothermometer to the magnitude of DO event temperature increase: the change in δ 18 O per Kelvin temperature increase reduces with DO event amplitude. We show that this effect is controlled by precipitation seasonality.
关键词：abrupt warmings ; climate change ; Arctic ; sea ice ; paleoclimate