Eugene S. Takle
© 13 May 1996
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.
Reference
Zielinski, G. A., P. A. Mayewski, L. D. Meeker, S. Whitlow, and M.S. Twickler, 1996: Potential atmospheric impact of the Toba mega-eruption ~71,000 years ago. Geophys. Res. Lett., 23, 837-840.