Transcript W4-1: Explosive Volcanoes and Climate Change

Explosive Events and
Climate Change
More frequent events than people
realize
The 535/6 AD event
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Remains controversial but there is a lot of
consistent evidence for a large volcanic
explosion
From Greece: "during this year a most
dread portent took place. For the sun
gave forth its light without brightness ...
and it seemed exceedingly like the sun in
eclipse, for the beams it shed were not
clear."
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England: The sun became dim ... for
nearly the whole year ... so that the fruits
were killed at an unseasonable time
Syria: The sun became dark and its
darkness lasted for eighteen months.
Each day it shone for about four hours,
and still this light was only a feeble
shadow ... the fruits did not ripen and the
wine tasted like sour grapes."
Europe
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"The sun ... seems to have lost its wonted
light, and appears of a bluish colour. We
marvel to see no shadows of our bodies
at noon, to feel the mighty vigour of the
sun's heat wasted into feebleness, and
the phenomena which accompany an
eclipse prolonged through almost a whole
year. We have had ... a summer without
heat ... the crops have been chilled by
north winds ... the rain is denied ..."
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Now tree-ring data, published by Professor Mike
Baillie of Queens University of Belfast, has
brought catastrophes almost into modern times.
The tree rings show that in the mid 530s -- just
about the time civilisation on Earth suffered a
sharp setback -- there was a sudden decline in
the rate of tree growth which lasted about 15
years. Clearly, something dramatic had
happened.
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“In China in 536 there was drought and
famine and “yellow dust rained like snow…
The crops were ruined the following year by
snow in August.””
“Starting in the 530s, a horrific 32-year long
drought devastated parts of South America.”
Antarctica and Greenland Evidence
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Scientists, again using ice-cores, discovered
evidence of a truly massive volcanic
eruption. The ice-core material revealed that
acid snow had cascaded down on the
Antarctic for at least four years
running….(This) occurred
sometime between 490 and 540.”
These explosive eruptions will generate a lot of acid rain due to the
high sulfur content of the emissions
1300 year later account 
campfire stories passed down?
There was a furious shaking of the earth, total darkness, thunder and
lightning… Then came a furious gale together with torrential rain and a
deadly storm darkened the entire world.”
The chronicle – known as the “Pustaka Raja Purwa (‘The book of Ancient
Kings’) … claims that the eruption was so massive that …. “After the
water subsided the mountain (which had burst into pieces) and the
surrounding land became sea and the (single) island (of Java/Sumatra)
divided into two parts. This (event) was the origin of the separation of
Sumatra and Java.” “
World wide trigger?
http://forums.civfanatics.com/archive/inde
x.php/t-116880.html
 Most of this is speculation but the
evidence for abrupt climate change is
pretty sound
 Speculation is that Kratatau was the
event:
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535 Krakatau Super Eruption
The Alternative Site
• A violent eruption occurred at Ilopango in the 5th century
AD.  erupted more than 70 cu km of tephra, produced
major ash fall and large pyroclastic flows that covered
10,000 sq km under 50 cm or more of pumice and ash.
Pyroclastic flows and ash fall devastated an area of up to
100 km radius around the volcano.
• The eruption severely impacted the Mayan culture living
in the highlands of El Salvador. The eruption killed
thousands, destroyed settlements and sent many to flee
to the lowland areas in Guatemala and Belize. It ended
the Mayan presence in the highlands.
• A major trade route controlled by the Mayas was
abandoned and power shifted to Tikal.
Major Hazards in the Area:
Where you gonna run?
84,000 years ago: Ash Fall out Density
Contours
Explosive Remnants. Santorini
Coatepeque Caldera in El Salvador
Galapagos
Pinatubo (1991)
Ngorongoro Crater
- Africa
Cape Verde Islands (1995)
Ethiopia 2008
Yellowstone hot spot calderas
Valles Caldera – NM –with rhyolite dome
Antarctica – similar to Santorini except no
Minoans there …
Silverthorne, BC – use your imagination
Near Rome
San Pedro, Guatemala
Biggest known Calderas