Ice Core Evidence of Recent Volcanic Contribution to Stratospheric Aerosols

Abstract:

Stratospheric sulfate aerosols formed from sulfur dioxide directly injected by explosive volcanic eruptions eventually deposit with snow onto polar ice sheets. Polar ice cores can provide evidence and a measure of stratospheric aerosol loading, as sulfate fallout is preserved within snow strata. A significant strength of these ice core records lies in the nature of their measurement: the volcanic sulfate is measured directly, complimenting indirect measurements with remote sensing or ground based optical methods. In the Antarctic, where the input of sulfate from anthropogenic activity is not pronounced, the contribution of volcanoes to the stratospheric sulfur budget may be readily investigated, even for small but highly explosive eruptions. For example, the Ozone Monitoring Instrument aboard the Aura satellite monitored the 2008 Chaitén eruption in the Southern Andes, and detected an estimated emission of 14 kt of sulfur dioxide to the atmosphere. A signal of the Chaitén eruption is seen in samples of recent snow and shallow ice cores from West Antarctica and the South Pole. This is consistent with the fact that the height of the eruption plume reached altitudes of up to 17 km, suggesting a stratospheric impact. The recent ice core data with signals of one or more explosive eruptions in the Southern Hemisphere during the twenty-first century indicates that a comparison of ice core records with instrumental measurement of stratospheric aerosols could be beneficial to a full determination of the stratospheric impact of volcanic eruptions during the first fifteen years of the twenty-first century.