The June 1991 eruption of Mount Pinatubo was global.
Slightly cooler than usual temperatures recorded worldwide
and the brilliant sunsets and sunrises have been attributed to this eruption
that sent fine ash and gases high into the stratosphere, forming a large
volcanic cloud that drifted around the world. The sulfur dioxide (SO2)
in this cloud -- about 22 million tons -- combined
with water to form droplets of sulfuric acid, blocking some of the
sunlight from reaching the Earth and thereby cooling
temperatures in some regions by as much as 0.5 degrees C. An eruption the
size of Mount Pinatubo could affect the weather for a few years.
A similar phenomenon occurred in April of 1815
with the cataclysmic eruption of Tambora Volcano in Indonesia,
the most powerful eruption in recorded history.
Tambora's volcanic cloud lowered global temperatures by as
much as 3 degrees C.
Even a year after the eruption, most of the
northern hemisphere experienced sharply cooler temperatures
during the summer months. In parts of Europe and in North America,
1816 was known as "the year without a summer."
Excerpts from:
Kious and Tilling, 1996,
This Dynamic Earth: The Story of Plate Tectonics:
USGS General Interest Publication
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