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High-frequency climate variability in the Holocene from a coastal-dome ice core in east-central Greenland
Climate of the Past ( IF 4.3 ) Pub Date : 2020-07-31 , DOI: 10.5194/cp-16-1369-2020
Abigail G. Hughes , Tyler R. Jones , Bo M. Vinther , Vasileios Gkinis , C. Max Stevens , Valerie Morris , Bruce H. Vaughn , Christian Holme , Bradley R. Markle , James W. C. White

An ice core drilled on the Renland ice cap in east-central Greenland contains a continuous climate record dating through the last glacial period. The Renland record is valuable because the coastal environment is more likely to reflect regional sea surface conditions compared to inland Greenland ice cores that capture synoptic variability. Here we present the δ18O water isotope record for the Holocene, in which decadal-scale climate information is retained for the last 8 kyr, while the annual water isotope signal is preserved throughout the last 2.6 kyr. To investigate regional climate information preserved in the water isotope record, we apply spectral analysis techniques to a 300-year moving window to determine the mean strength of varying frequency bands through time. We find that the strength of 15–20-year δ18O variability exhibits a millennial-scale signal in line with the well-known Bond events. Comparison to other North Atlantic proxy records suggests that the 15–20-year variability may reflect fluctuating sea surface conditions throughout the Holocene, driven by changes in the strength of the Atlantic Meridional Overturning Circulation. Additional analysis of the seasonal signal over the last 2.6 kyr reveals that the winter δ18O signal has experienced a decreasing trend, while the summer signal has predominantly remained stable. The winter trend may correspond to an increase in Arctic sea ice cover, which is driven by a decrease in total annual insolation, and is also likely influenced by regional climate variables such as atmospheric and oceanic circulation. In the context of anthropogenic climate change, the winter trend may have important implications for feedback processes as sea ice retreats in the Arctic.

中文翻译:

格陵兰中东部沿海穹顶冰芯的全新世高频气候变化

在格陵兰中东部的伦兰(Renland)冰帽上钻出的冰芯包含了自上个冰川期以来的连续气候记录。Renland的记录很有价值,因为与捕获天气变化的内陆格陵兰冰芯相比,沿海环境更可能反映区域海表状况。在这里,我们目前的I' 18 Ø全新世的水同位素记录,其中在最后8个kyr保留了十年尺度的气候信息,而在最后2.6个kyr则保留了年度水同位素信号。为了调查保存在水同位素记录中的区域气候信息,我们将频谱分析技术应用于300年的移动窗口,以确定随时间变化的不同频段的平均强度。我们发现,15A ???? 20岁的强度I' 18 Ø可变性表现出与众所周知的邦德事件一致的千年尺度信号。与其他北大西洋代理记录的比较表明,15-20年的变化可能反映了整个全新世海平面条件的波动,这是由大西洋子午俯仰环流强度的变化驱动的。在过去的2.6A ???? KYR表明,冬季季节性信号的附加分析I' 18 Ø信号呈下降趋势,而夏季信号主要保持稳定。冬季趋势可能对应于北极海冰覆盖面积的增加,这是由年度总日射量的减少所驱动的,并且也可能受区域气候变量(例如大气和海洋环流)的影响。在人为气候变化的背景下,冬季趋势可能对北极海冰撤退时的反馈过程产生重要影响。
更新日期:2020-08-20
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