2600-years of stratospheric volcanism through sulfate isotopes

E Gautier,S Hattori,J Erbland,J Farquhar,J Savarino,E Albalat,F Albarede,N Yoshida,J Hoek,N Caillon

doi:10.1038/s41467-019-08357-0

Abstract

High quality records of stratospheric volcanic eruptions, required to model past climate variability, have been constructed by identifying synchronous (bipolar) volcanic sulfate horizons in Greenland and Antarctic ice cores. Here we present a new 2600-year chronology of stratospheric volcanic events using an independent approach that relies on isotopic signatures (Δ33S and in some cases Δ17O) of ice core sulfate from five closely-located ice cores from Dome C, Antarctica. The Dome C stratospheric reconstruction provides independent validation of prior reconstructions. The isotopic approach documents several high-latitude stratospheric events that are not bipolar, but climatically-relevant, and diverges deeper in the record revealing tropospheric signals for some previously assigned bipolar events. Our record also displays a collapse of the Δ17O anomaly of sulfate for the largest volcanic eruptions, showing a further change in atmospheric chemistry induced by large emissions. Thus, the refinement added by considering both isotopic and bipolar correlation methods provides additional levels of insight for climate-volcano connections and improves ice core volcanic reconstructions.

Highlights

Sulfurous gases are rapidly oxidized to sulfuric acid aerosols upon entering the stratosphere[10], and once formed, product aerosols can persist for 1–4 years and spread around one or both hemispheres depending on whether injection occurred at high or low latitude
Such records are based on the inference that bipolar signals uniquely link volcanic sulfate to low latitude stratospheric eruptions
The isotopic method is based on the principle that SO2 emitted by a point volcanic source starts with a mass-dependent composition (Δ33S = 0)[21] and acquires a mass-independent composition (Δ33S ≠ 0, hereafter referred to as sulfur isotope anomaly) if subject tooxidation (SO2 to sulfate) by shortwave UV radiation that is present only in and above stratospheric ozone[22,23], but carries a mass-dependent composition if oxidized below this ozone layer[24]

Summary

Introduction

Sulfurous gases are rapidly oxidized to sulfuric acid aerosols upon entering the stratosphere[10], and once formed, product aerosols can persist for 1–4 years and spread around one or both hemispheres depending on whether injection occurred at high or low latitude. Such records are based on the inference that bipolar signals uniquely link volcanic sulfate to low latitude stratospheric eruptions.

Results

Conclusion