Shedding Light on Earth's Volcanic Past Using Arrays of Ice Cores: How Common is Present-Day Volcanic Activity in a Multi-Millennial Context?

Abstract:

Volcanic eruptions have been identified as a primary driver of climate variability, impacting surface air temperature, atmospheric circulation and hydroclimate. The observational record of the timing of volcanic eruptions, their location, magnitude of sulfate aerosol injection and its atmospheric life-cycle, however, is often incomplete, with gaps in our record of past volcanic activity increasing dramatically before the Modern (pre-1800) era. This shortage in observational data strongly limits our understanding of the sensitivity of the Earth system to volcanism and the vulnerability of social and economic systems to the climate impact of past and future eruptions. As a consequence, climate impact and future risk assessments are presently based on climate model simulations that do not include realistic volcanic influences in the 21^st century and hence do not cover the range of possible future outcomes. Now a 2,500 year-long ice-core record of volcanic activity (Sigl et al., 2015) and resulting stratospheric sulfur injections (Toohey & Sigl, 2017), shed new light on potential future volcanism (Bethke et al., 2017). Sulfuric acid layers in ice cores prove that several centuries were volcanically much more active than the recent one, calling into question the decision of modeling groups to omit plausible eruptions in future climate simulations. The Holocene (i.e. the past 11,700 years) saw a number of eruptions with sulfur injections outside the range modern human societies experienced. I demonstrate how we can extract comprehensive data on the timing, magnitudes and source locations of past volcanic eruptions, using a bi-polar array of ice-core records from Greenland and Antarctica and employing novel, precisely dated, high-time resolution, aerosol measurements from ice cores.

References:

Bethke, I., Outten, S., Otterå, O. H., Hawkins, E., Wagner, S., Sigl, M., and Thorne, P.: Potential volcanic impacts on future climate variability, Nature Climate Change, 7, 799-804, 2017.

Sigl, M. et al.: Timing and climate forcing of volcanic eruptions for the past 2,500 years, Nature, 523, 543–549, 2015.

Toohey, M. & Sigl, M.: Volcanic stratospheric sulfur injections and aerosol optical depth from 500BCE to 1900CE, Earth Syst Sci Data, 9, 809–831, 2017.