Volcanic Winter? Climatic Effects of the Largest Volcanic Eruptions
Calculations suggest that the largest volcanic eruptions could have significant effects on global climate. We estimate the amount of sulfur volatiles that could have been released in very large eruptions by scaling up from smaller historical eruptions. The greatest well-known Late Quaternary explosive eruption, Toba (Indonesia, 75,000 years B.P.) erupted at least 1000 km3 of magma, and may have released enough sulfur volatiles to have formed 9 × 1014 to 5 × 1015 g of H2SO4 stratospheric aerosols. Basaltic fissure eruptions release even greater amounts of sulfur volatiles, which can be lofted into the stratosphere in convective plumes rising above fire fountains. The Roza flow eruption (about 700 km3 of magma) of the Miocene Columbia River Basalt Group could have produced up to 6 × 1015 g of aerosols. Distributed worldwide, these aerosol mass loadings would lead to effects ranging from a noticeable dimming of the sun to conditions similar to those described in some models of nuclear winter. Unless self-limiting mechanisms of stratospheric aerosol formation and removal are important, very large eruptions may lead to widespread darkness, cold weather, and acid precipitation. Even the minimum estimated effects of these great eruptions would represent significant perturbations of the global atmosphere.
KeywordsDust Europe Attenuation Chlorine Acidity
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