Abstract
Abstract. Large volcanic eruptions occurring in the last glacial period can be detected by their accompanying sulfuric acid deposition 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 kyr before 2000 CE (b2k). Over most of the investigated interval the ice cores are synchronized, 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 large variability in the sulfate background signal, particularly in the Greenland glacial climate, we only list 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 737 eruptions in Antarctica within the 51 kyr period – for which the sulfate deposition of 85 eruptions is found at both poles (bipolar eruptions). Based on the ratio of Greenland and Antarctic sulfate deposition, we estimate the latitudinal band of the bipolar eruptions and assess their approximate climatic forcing based on established methods. A total of 25 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 Tambora, Indonesia, eruption (1815 CE). 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. This confirms the suggestion that the isostatic unloading of the Northern Hemisphere (NH) ice sheets may be related to the enhanced NH volcanic activity. Our ice-core-based volcanic sulfate records provide the atmospheric sulfate burden and estimates of climate forcing for further research on climate impact and understanding the mechanism of the Earth system.
Highlights
The dispersal of gas, aerosols and ash particles by volcanic eruptions plays a major role in the climate system
Using a 20 kg km−2 deposition threshold, 1113 volcanic events are identified in Greenland in total (Table S3)
We investigate the variability in eruption frequency and sulfur emission strength with the DO cycles by separating the detected volcanic eruptions according to the climate of “cold” and “milder” periods and applying the onset and termination of DO events defined by Rasmussen et al (2014)
Summary
The dispersal of gas, aerosols and ash particles by volcanic eruptions plays a major role in the climate system Large volcanic eruptions injecting sulfuric gases into the stratosphere and forming sulfate aerosols have a global or hemispheric cooling effect of several degrees lasting for several years after the eruption (Sigl et al, 2015; Sinnl et al, 2021). Estimations of volcanic stratospheric sulfur injections and of the timing and frequency of large volcanic eruptions are essential for the ability to understand and model past and future global climate conditions (Timmreck et al, 2016). For the last 1200 to 2500 years, the ice-core-based volcanic forcing records derived from Greenland and Antarctica (Crowley and Unterman, 2013; Gao et al, 2008; Toohey and Sigl, 2017) provide an essential forcing record for climate model simulations (Jungclaus et al, 2017), supporting detection and attribution studies (Schurer et al, 2014), including those applied in the IPCC. The global ice-core-based volcanic record of the last glacial period has been poorly documented
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