Evidence of volcanic loading of the atmosphere and climate response

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Global climatic effects brought about by volcanism are most likely to be related to the impact of volcanic gases and their derivative aerosols on the atmosphere, rather than the effects of volcanic ash. Evidence from both historic eruptions and polar ice cores indicates that volcanic sulfur gases are the dominant aerosol-forming component, resulting in production of a sulfuric acid-rich stratospheric aerosol that can have profound effects on the Earth's radiation budget over periods of a few years. Due to highly variable sulfur content of different magma types, the climatic effects do not relate simply to total erupted mass. Data on several recent eruptions indicate a close relationship between volcanic sulfur yield to the atmosphere and hemisphere surface temperature decrease following the eruptions, with up to 1° C surface temperature decrease indicated following a major volcanic event such as the 1815 Tambora eruption. While the erupted mass of HCl and HF is equal to or greater than that of sulfur gases in a number of volcanic events, the halogens do not form known aerosols nor are they abundant in ice core acidity layers. Current opinion favors the early removal of halogens from eruption columns by rain flushing and adsorption onto tephra particles, but the fate of halogens in the atmosphere following very large explosive eruptions remains unstudied. CO2 flux to the atmosphere from volcanic eruptions is volumetrically one of the most important of the gas species, but owing to the huge size of the atmospheric reservoir of this gas, the volcanic contribution is likely to have negligible effects, even for event on the scale of the Deccan Traps. © 1990.

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Global and Planetary Change