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Volcanic eruption role in K-Pg extinction may have been less severe than thought



Ben Creisler
bcreisler@gmail.com

A new paper:

Anja Schmidt, Richard A. Skeffington, Thorvaldur Thordarson, Stephen
Self, Piers M. Forster, Alexandru Rap, Andy Ridgwell, David Fowler,
Marjorie Wilson, Graham W. Mann, Paul B. Wignall & Kenneth S. Carslaw
(2015)
Selective environmental stress from sulphur emitted by continental
flood basalt eruptions
Nature Geoscience (advance online publication)
doi:10.1038/ngeo2588
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2588.html

Several biotic crises during the past 300 million years have been
linked to episodes of continental flood basalt volcanism, and in
particular to the release of massive quantities of magmatic sulphur
gas species. Flood basalt provinces were typically formed by numerous
individual eruptions, each lasting years to decades. However, the
environmental impact of these eruptions may have been limited by the
occurrence of quiescent periods that lasted hundreds to thousands of
years. Here we use a global aerosol model to quantify the
sulphur-induced environmental effects of individual, decade-long flood
basalt eruptions representative of the Columbia River Basalt Group,
16.5–14.5 million years ago, and the Deccan Traps, 65 million years
ago. For a decade-long eruption of Deccan scale, we calculate a
decadal-mean reduction in global surface temperature of 4.5 K, which
would recover within 50 years after an eruption ceased unless climate
feedbacks were very different in deep-time climates. Acid mists and
fogs could have caused immediate damage to vegetation in some regions,
but acid-sensitive land and marine ecosystems were well-buffered
against volcanic sulphur deposition effects even during century-long
eruptions. We conclude that magmatic sulphur from flood basalt
eruptions would have caused a biotic crisis only if eruption
frequencies and lava discharge rates had been high and sustained for
several centuries at a time.


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News release:

http://www.leeds.ac.uk/news/article/3795/drawing_a_curtain_of_fire_on_dinosaur_extinction_theory