Stratospheric eruptions from tropical and extra-tropical volcanoes constrained using high-resolution sulfur isotopes in ice cores

• Published in: Earth and Planetary Science Letters
• Main Authors: Burke, Andrea, Moore, Kathryn A., Sigl, Michael, Nita, Dan C., McConnell, Joseph R., Adkins, Jess F.
• Other Authors: European Commission, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Volcanoes; Sulfur; Mass-independent fractionation; Stratosphere; Katmai; Ice cores; GE Environmental Sciences; DAS; SDG 13 - Climate Action; GE; Greenland; Antarc*; Antarctica; ice core
• Online Access: http://hdl.handle.net/10023/20111; https://doi.org/10.1016/j.epsl.2019.06.006

This research was funded by a Foster and Coco Stanback postdoctoral fellowship and a Marie Curie Career Integration Grant (CIG14-631752) to AB and a NSF-OCE grant 1340174 and NSF-EAR grant 1349858 to JFA. MS acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 820047). NSF-PLR grant 1204176 to JRM supported collection and analysis of the Tunu2013 core. The record of volcanic forcing of climate over the past 2500 years is based primarily on sulfate concentrations in ice cores. Of particular interest are large volcanic eruptions with plumes that reached high altitudes in the stratosphere, as these afford sulfate aerosols the longest residence time in the atmosphere, and thus have the greatest impact on radiative forcing. Sulfur isotopes measured in ice cores can be used to identify these large eruptions because stratospheric sulfur is exposed to UV radiation, which imparts a time-evolving mass independent fractionation (MIF) that is preserved in the ice. However, sample size requirements of traditional measurement techniques mean that the MIF signal may be obscured, leading to an inconclusive result. Here we present a new method of measuring sulfur isotopes in ice cores by multi-collector inductively coupled plasma mass spectrometry, which reduces sample size requirements by three orders of magnitude. Our method allows us to measure samples containing as little as 10 nmol of sulfur, with a precision of 0.11‰ for δ34S and 0.10‰ for Δ33S, enabling a high-temporal resolution over ice core sulfate peaks. We tested this method on known tropical (Tambora 1815 and Samalas 1257) and extra-tropical (Katmai/Novarupta 1912) stratospheric eruptions from the Tunu2013 ice core in Greenland and the B40 ice core from Antarctica. These high-resolution sulfur isotope records suggest a distinct difference between the signatures of tropical versus extra-tropical eruptions. Furthermore, isotope mass balance on sulfate from ...