Download Climate and Volcanism - Natural Climate Change

Climate and Volcanism
By: Jared Lung
Quick Facts
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Volcanoes tend to exist along the edges of tectonic plates,
massive rock slabs that make up Earth's surface.
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About 90 percent of all volcanoes exist within the Ring of
Fire along the edges of the Pacific Ocean.
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Volcanoes are active, meaning they show some level of
activity and are likely to explode again, dormant, showing
no current signs of exploding but are likely to become
active at some point in the future, or extinct meaning they
won’t be active again.
About 1,900 volcanoes on Earth are considered active.
Early Earth
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About 4 billion years ago, planet Earth had
no atmosphere and its surface was
covered with erupting volcanoes.
All the water in the oceans and many of
the gases that make up the atmosphere
have been produced by volcanoes
erupting.
The volcanoes released water vapor,
carbon dioxide, and sulfur dioxide into the
environment.
Climate Vs. Weather
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Weather can change from minute-to-minute,
hour-to-hour, day-to-day, and season-to-season.
Climate, however, is the average of weather over
time and space.
An easy way to remember the difference is that
climate is what you expect, like a very hot
summer, and weather is what you get, like a hot
day with pop-up thunderstorms.
Volcanoes can have HUGE affects on the weather
but typically, only the really big eruptions will
have noticeable effects on the climate.
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An eruption can cause warming and
cooling.
• An addition of carbon dioxide
contributes to greenhouse warming.
• An addition to sulfurous gases induces
cooling, because they turn into droplets
of sulfuric acid that absorb and reflect
sunlight, and cut down the amount of
heat that reaches the ground.
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But most documented cases show a
net cooling effect.
Benjamin Franklin
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The first scientist to
recognize the cooling
pattern.
He linked the abnormal
weather over Europe in
1783-84 to the great
Laki eruption in Iceland,
which sent volcanic
gases into the
stratosphere and
released over 100
million tons of sulfur
dioxide over just a
couple of months – As
much as the world’s
industries release today
in a year.
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In May 1784, in a communication to the
Literary and Philosophical Society of
Manchester, England, about the haze
covering the land, Franklin wrote:
The cause of this universal fog is not yet
ascertained. Whether it was adventitious to
this Earth, and merely a smoke proceeding
from the consumption by fire of some of those
great burning balls or globes which we happen
to meet with in our rapid course around the
sun, … or whether it was the vast quantity
of smoke, long continuing to issue during
the summer from Hecla, Iceland, … which
smoke might be spread by various winds
over the northern part of the world, is yet
uncertain.
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Most major eruptions only cause a
temperature change of a fraction of a
Kelvin, which doesn’t sound like
much, but over an entire year it
represents a large amount of heat
subtracted from the Earth’s budget.
Smaller eruptions don’t have a very
big effect on the climate.
The two major variations of temperature in the atmosphere are
due to the eruption of El Chichon volcano in Mexico (1982) and
Pinatubo volcano in the Philippines (1991).
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The change in temperature can have
serious repercussions on food crops and
human health.
The harsh winter that followed the
eruption of Laki in 1783, played a role in
the poor harvests and the famines that led
up to the French Revolution.
Chinese records mention similar droughts
and freezing events following major
eruptions, such as Thera-Santorini in 1620
BC and Mount Etna in 44 BC.
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The effect of an eruption on climate is
greatest when the gas plume penetrates
the stratosphere.
Unlike the lower atmosphere, the
stratosphere does not have rain clouds as
a mechanism to quickly wash out
pollutants. Therefore, a heavy influx of
aerosol pollutants will remain in the
stratosphere for years until the processes
of chemical reactions and atmospheric
circulation can filter them out.
High-altitude winds can carry the particles
and ash far distances.
Chaiten volcano captured by NASA's Terra
satellite at 10:35 a.m. local time on May
3, 2008.
Can Ash Float Around the Globe?
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Yes! In June of 1991 the eruptions of
Mount Pinatubo in the Philippines
spewed ash and gas into the
atmosphere.
By July 25th the particles had spread
around the world.
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Because they scatter and absorb incoming
sunlight, aerosol particles exert a cooling
effect on the Earth’s surface. The Pinatubo
eruption increased aerosol optical depth in
the stratosphere by a factor of 10 to 100
times normal levels measured prior to the
eruption.
“Aerosol optical depth” is a measure of
how much light, airborne particles prevent
from passing through a column of
atmosphere.
Consequently, over the next 15 months,
scientists measured a drop in the average
global temperature of about 1 degree F or
0.6 degrees C.
Eruptions
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A powerful ashy eruption can cause
dark days, severe winds, and heavy
falls of rain and mud for months.
A volcanic eruption that sends gas
and dust into the atmosphere can
alter the climate of the whole planet.
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Volcanoes blast huge clouds into the atmosphere made up of
gases and particles including sulfur dioxide, water vapor, and
carbon dioxide.
In the atmosphere, water vapor and sulfur dioxide convert to tiny
sulfuric acid aerosols which reflect energy coming from the sun,
thereby preventing the sun's rays from heating Earth's surface.
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Dark dust particles absorb sunlight,
and light-colored aerosols reflect
sunlight.
The amount of heat reaching the
Earth is reduced and thus the surface
temperatures are reduced.
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The particles also affect our views of the
sun and moon by scattering certain kinds
of sunlight and letting other kinds through
the atmosphere.
This can cause spectacular sunrises and
sunsets.
The sun and moon may seem to be
wrapped in halos or to glow with strange
colors.
A sunset caused by the light-scattering
effects of the volcanic ash thrown up into
the atmosphere by the eruption of
Iceland's volcano Eyjafjallajokull.
Long Term Affects
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Volcanic particles can cause
occurrences such as:
• Global Cooling
• Mass Extinctions
• Ice Ages
Little Ice Ages
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1783 – Skaftar in Iceland and Mount
Asama in Japan erupted.
These eruptions were followed by
several very cold winters in Europe
and America.
They caused unusually thick polar ice
to form.
Mass Extinction
One scientific theory proposes that
massive volcanic eruptions produced
enough gas and dust to cool global
temperatures and kill off the dinosaurs.
Famous Volcanoes
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Krakatoa, Mount Pinatubo, Tambora,
Vesuvius, Mount Pelee, El Chichon,
Laki, Eyjafjallajokull, and Mount St.
Helens
Krakatoa
Krakatoa
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In 1883, Krakatoa in Indonesia erupted.
It blew dust over 80 km into the air with a
force of about 100 million tons of
dynamite.
The explosions were heard across the
Indian Ocean and all the way in Australia,
2,400 miles away.
Produced orange and red sunsets for
several years.
It panicked American firefighters into
battling what they thought were raging
infernos, but were actually violent sunsets
caused by the Krakatoan dust.
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Ash was reported over a 750,000 sq
km area.
Shock of the eruption caused huge
waves with breakers over 40 m high.
The dust from the eruption caused a
decrease in temperature by ½ a
degree centigrade worldwide.
The cooling effect lasted for about 10
years.
Mount Pinatubo
Mount Pinatubo
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Erupted in 1991, in the Philippines.
Sulfur containing gases were spewed into the
atmosphere blocking sunlight and falling back to
Earth as acid rain.
The unusually cool Northern Hemisphere summer
of 1992 has caused meteorologists to increase
their look at the role of volcanic eruptions in
world-wide weather patterns.
There was a temperature decrease of about 0.3
Kelvins.
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Mount Pinatubo erupted with a tremendous force,
ejecting vast amounts of ash and gas high into
the atmosphere; so high that the volcano’s plume
penetrated into the stratosphere. The
stratosphere is the layer of atmosphere extending
from about 10 km to 50 km (6-30 miles) in
altitude.
Pinatubo injected about 15 million tons of sulfur
dioxide into the stratosphere, where it reacted
with water to form a hazy layer of aerosol
particles composed primarily of sulfuric acid
droplets. Over the course of the next two years
strong stratospheric winds spread these aerosol
particles around the globe.
The effect of the 1991 Pinatubo eruption on
the Greenland Ice Sheet
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The reduced air temperatures during the 1992
northern hemisphere summer had effects on the
mass balance of glaciers. This is well illustrated
by a diagram in the 2005 ACIA (Arctic Climate
Impact Assessment) report. Unfortunately, the
special background for the extraordinary low
summer melting of 1992 appears not to have
been recognized by the authors of the report.
Consequently, the year 1992 and 2002 were
erroneously presented in the ACIA report as
visually demonstrating the effect on the
Greenland Ice Sheet of late 20th century
warming in the Arctic.
Tambora
Tambora
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1815 – Located in Indonesia.
Put out over 100 million tons of
sulfur dioxide.
Worldwide there was a temperature
drop of close to 0.5 Kelvins.
Mt. Tambora also happened during
the Dalton Minimum, increasing the
cooling effects that were already
occuring from low sunspot activity.
Results of Tambora
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Temperatures in New England dropped an
estimated 1-2 Kelvins, it snowed in July, and
1816 became known as ‘the year without a
summer’.
Tambora changed the climate so much that crops
in Europe and north America failed in the
following years.
Tens of thousands of people were killed by the
apocalyptic eruption, subsequent tsunamis and
ensuing starvation and disease.
Mount Vesuvius
Mount Vesuvius
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Rises 1,279 meters above the Bay of Naples in
Italy.
The most widely known volcano on Earth and one
of the most thoroughly studied.
Mount Vesuvius has experienced eight major
eruptions in the last 17,000 years.
Mount Vesuvius is responsible for the destruction
of the Roman cities of Herculaneum and Pompeii
in AD 79.
Mount Vesuvius is regarded as one of the most
dangerous volcanoes in the world because of the
potential danger it poses to the population of
3,000,000 people living close to it. It is the most
densely populated volcanic region in the world.
Mount St. Helens
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At 8:32 a.m. on May 18, 1980, a 5.1-magnitude
earthquake triggered a sideways blast that swept
the mountain's north face away into a cascading
landslide that shot hot ash and stone out some
15 miles at speeds of at least 300 m.p.h.
At the same time, a mushroom-shaped plume of
ash shot 16 miles into the air, eventually covering
three states. Complete darkness blanketed
Spokane, Wash., a city about 250 miles northeast
of the volcano. When the ash came down it fell in
the form of black rain that literally coated the
residents of Washington, Idaho and parts of
Montana with a fine gray powder.
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The 1980 eruption of Mt. St. Helens did
not have much affect on global
temperatures for two reasons.
• The eruption of Mount St. Helens was not very
large compared to other volcanoes that did
affect global temperatures in the past.
• The energy emitted by this eruption went
sideways, rather than vertically, therefore
particles did not enter high enough into the
atmosphere to reflect sunlight.
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