Magnitude, frequency and climate forcing of global volcanism during the last glacial period as seen in Greenland and Antarctic ice cores (60–9 ka)
Magnitude, frequency and climate forcing of global volcanism during the last glacial period as seen in Greenland and Antarctic ice cores (60–9 ka)
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DOI：
10.5194/cp-2021-100
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发表时间：
2021-08
影响因子：
4.3
通讯作者：
Jia-Chun Lin;A. Svensson;C. Hvidberg;J. Lohmann;S. Kristiansen;D. Dahl-Jensen;J. Steffensen;S. Rasmussen;E. Cook;H. Kjær;B. Vinther;H. Fischer;T. Stocker;M. Sigl;M. Bigler;M. Severi;R. Traversi;R. Mulvaney
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作者：
Jia-Chun Lin;A. Svensson;C. Hvidberg;J. Lohmann;S. Kristiansen;D. Dahl-Jensen;J. Steffensen;S. Rasmussen;E. Cook;H. Kjær;B. Vinther;H. Fischer;T. Stocker;M. Sigl;M. Bigler;M. Severi;R. Traversi;R. Mulvaney
摘要。末次冰期发生的大型火山喷发可以通过连续冰芯中沉积的硫酸来探测。本文利用格陵兰岛三个冰芯和南极三个冰芯的连续硫酸盐和硫记录，估算了末次冰期下半期和全新世早期（公元2000年之前60 - 9ka年）发生的大型火山喷发的排放强度、频率和气候强迫。冰芯在大部分研究区间内是同步的，这使得区分具有全球硫酸盐分布的大喷发与仅在一个半球可检测到的喷发成为可能。由于有限的数据分辨率和硫酸盐背景信号的大变异性，特别是在格陵兰冰川气候中，我们只检测到格陵兰大于20 kg km−2的硫酸盐沉积和南极大于10 kg km−2的硫酸盐沉积。根据这些限制，我们确定了51ka期间格陵兰岛的1113次火山喷发和南极洲的740次火山喷发，其中85次喷发的硫酸盐沉积被定义为两极（双极喷发）。基于格陵兰岛和南极的相对硫酸盐沉积，我们估计了两极喷发的纬度带，并根据现有的方法评估了它们的近似气候强迫。据估计，5次最大喷发的气候强迫值高于- 70 W m−2。已确定的双极火山喷发中有27次比过去2500年来发生的任何火山喷发都要大，据估计有69次喷发的硫排放强度比公元1815年发生在印度尼西亚的VEI-7 Tambora火山喷发要大。通过硫排放强度对比发现，比典型VEI-7 （VEI-8）型喷发更大的喷发频率比地质证据估计的高5.3(7)倍。在整个研究期间，火山爆发的频率相当稳定，与近代相当。然而，在冰期（16-9 ka b2k）期间，格陵兰岛记录到的火山事件频率显著增加，超大型火山喷发的比例明显增加。对南极洲来说，去冰期不能与其他时期区分开来。这些记录在冰芯中的火山为进一步研究气候影响和了解地球系统的机制提供了大气硫酸盐负荷和气候强迫。
Abstract. Large volcanic eruptions occurring in the last glacial period can be detected in terms of their deposited sulfuric acid in continuous ice cores. Here we employ continuous sulfate and sulfur records from three Greenland and three Antarctic ice cores to estimate the emission strength, the frequency and the climatic forcing of large volcanic eruptions that occurred during the second half of the last glacial period and the early Holocene, 60–9 ka years before AD 2000 (b2k). The ice cores are synchronized over most of the investigated interval making it possible to distinguish large eruptions with a global sulfate distribution from eruptions detectable in one hemisphere only. Due to limited data resolution and to a large variability in the sulfate background signal, particularly in the Greenland glacial climate, we only detect Greenland sulfate depositions larger than 20 kg km−2 and Antarctic sulfate depositions larger than 10 kg km−2. With those restrictions, we identify 1113 volcanic eruptions in Greenland and 740 eruptions in Antarctica within the 51 ka period – where the sulfate deposition of 85 eruptions is defined at both poles (bipolar eruptions). Based on the relative Greenland and Antarctic sulfate deposition, we estimate the latitudinal band of the bipolar eruptions and assess their approximate climatic forcing based on established methods. The climate forcing of the five largest eruptions is estimated to be higher than −70 W m−2. Twenty-seven of the identified bipolar eruptions are larger than any volcanic eruption occurring in the last 2500 years and 69 eruptions are estimated to have larger sulfur emission strengths than the VEI-7 Tambora eruption that occurred in Indonesia in 1815 AD. The frequency of eruptions larger than the typical VEI-7 (VEI-8) eruption by the comparison of sulfur emission strength is found to be 5.3 (7) times higher than estimated from geological evidence. Throughout the investigated period, the frequency of volcanic eruptions is rather constant and comparable to that of recent times. During the deglacial period (16–9 ka b2k), however, there is a notable increase in the frequency of volcanic events recorded in Greenland and an obvious increase in the fraction of very large eruptions. For Antarctica, the deglacial period cannot be distinguished from other periods. These volcanoes documented in ice cores provide atmospheric sulfate burden and climate forcing for further research on climate impact and understanding the mechanism of the Earth system.