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Have Volcanoes Caused Ice
Ages?
PREVIOUS: Jet Contrails Impact on the
Radiation Budget
The eruption of Mt. Pinatubo spewed enough debris into the
atmosphere to lead to a global cooling of a few tenths of a
degree that lasted for a couple of years before gradually
diminishing. Since this was a medium-sized volcano by comparison
to some eruptions known from geological history, what would
happen to climate if a major eruption occurred? Richard Kerr
(Science 272, 817; 10 May 1996) summarizes some recent data
suggesting that huge volcanoes don't necessarily lead to major
long-term cooling.
Gregory Zelinsky et al (1996) report recent analysis of the
Greenland ice core that lends new insight on this issue. The
volcano Toba that erupted in the Indonesian island of Sumatra
71,000 years ago put about 100 times as much sulfuric acid into
the atmosphere (1 to 10 billion tons) as did Mt. Pinatubo.
Although conclusive evidence has not been presented, it is now
estimated that such an event might cause a 3 - 5 degree C cooling
for a few years but would not likely plunge the planet into a
prolonged cold period. More acid likely means larger droplets
which would fall out quicker and allow the surface temperature to
recover relatively quickly.