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Explosive volcanism as a key driver of the late Paleozoic ice age

Gerilyn S. Soreghan, Michael J. Soreghan and Nicholas G. Heavens
Explosive volcanism as a key driver of the late Paleozoic ice age
Geology (Boulder) (May 2019) 47 (7): 600-604


Atmospheric CO (sub 2) exerts a robust and well-documented control on Earth's climate, but the timing of glaciation during the late Paleozoic Ice Age (LPIA; ca. 360-260 Ma) is inconsistent with pCO (sub 2) reconstructions, hinting at another factor. Stratospheric volcanic aerosols produce a large but temporary negative radiative forcing under modern conditions. Here we examine explosive volcanism over 200 m.y. of Earth history to show that the LPIA corresponded with a sustained increase in volcanism in both tropical and extratropical latitudes. A major peak in explosive volcanism at ca. 300 Ma likely corresponded to stratospheric sulfur-injecting eruptions at least three to eight times more frequent than at present. This level of volcanism created a steady, negative radiative forcing potentially sufficient to initiate and, most critically, sustain icehouse conditions, even under increasing levels of pCO (sub 2) , and helps resolve discrepancies between glacial timing and CO (sub 2) records. Accounting for the radiative forcing effects of CO (sub 2) and sulfate indicates that both are required to explain the LPIA, with sulfate producing an especially strong effect at peak icehouse ca. 298-295 Ma. Frequent explosive volcanism would have increased atmospheric acidity, enhancing the reactivity of iron in abundant volcanic ash and glacially generated mineral dust, thus strengthening the climate impact of volcanism through a marine biological pump further primed by feedback with glaciation.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 47
Serial Issue: 7
Title: Explosive volcanism as a key driver of the late Paleozoic ice age
Affiliation: University of Oklahoma, School of Geology and Geophysics, Norman, OK, United States
Pages: 600-604
Published: 20190502
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 53
Accession Number: 2019-046832
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2019219
Illustration Description: illus.
Secondary Affiliation: Hampton University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201924
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