Transcript Mt. Pinatubo - Institute for Global Environmental Strategies

MT. PINATUBO:
VOLCANOES AND THE
EARTH
Razakh Abdirahman
Asia David
April Ortega
Megan Ortiz
PROBLEM STATEMENT
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Though scientists are still discovering if volcanoes cause a major shift in a global climate
change, we do know the temperatures following a great eruption such as Mt. Pinatubo
and Tambora, that climate changed by about 2 degrees Celsius. The aerosols put out by
volcanic eruptions remain in the air for months up to a year causing a slow change in
temperatures and eventually affecting the climate. These aerosols which contain, sulfur
dioxide, water vapor and hydrochloric acid reflect the sun’s radiation and cause a cooling
effect. These aerosols also affect the Earth’s surface albedo, causing an increase in the
albedo, leading for an even greater cooling effect. A solution for geo-engineering against
the problem of global warming would to recreate an artificial volcano. Releasing gases
into the stratosphere would result in a cooling of the Earth’s surface since a greater
amount of the sun’s radiation would be reflected back into space.
Our team has explored geo-engineering options such as aerosol injections into the
atmosphere, which have a greater cooling effect yet carry the greatest risk; the addition of
phosphorous into the ocean that may have a long-term carbon seclusion potential than
deliberately adding iron or nitrogen; Cities can also offset the heat by increasing the
reflectivity of urban areas with the usage of white walls and buildings, but may only have a
minimal global effect. Two other options include a plan to include ocean pipes and
increases in cloud reflectivity, and adding ‘bio-char’ (charcoal added back into the soil)
that has a short-term cooling effect.
BACKGROUND: 1816 TAMBORA
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Indonesia
13,000 ft before
9,348 ft elevation after
Stratovolcano
Caldera 3,640 ft deep
VEI=7
The volcano threw sulfur dioxide gas into the stratosphere, and the aerosol layer that formed led to brilliant sunsets seen around the world for
several years.
Pyroclastic flows reached the sea on all sides of the peninsula and heavy tephra fall devastated croplands, causing an estimated 60,000
fatalities. The eruption of more than 150 cubic kilometers of tephra formed a 6-kilometer-wide, 1250-meter-deep caldera and produced global
climatic effects. Minor lava domes and flows have been extruded on the caldera floor during the 19th and 20th centuries.
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."
Volcanic Explosivity Index (VEI) is a scale that describes the size
of an explosive volcanic eruption. VEI is analogous to the Richter
magnitude scale for earthquakes. In the 0 to 8 scale of VEI,
each interval represents an increase of a factor of ten. An
eruption of VEI 4 is 10 times larger than a 3 and one hundred
times larger than a 2. Key characteristics that define VEI
include: Volume of ash produced
Height of eruption cloud above the vent
Duration of eruption
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The 1815 eruption of Tambora was the largest eruption in historic time. About 150
cubic kilometers of ash were erupted (about 150 times more than the 1980 eruption
of Mount St. Helens). Ash fell as far as 800 miles (1,300 km) from the volcano. In
central Java and Kalimantan, 550 miles (900 km) from the eruption, one centimeter
of ash fell. The Volcanic Explosivity of the eruption was 7. The eruption column
reached a height of about 28 miles (44 km). The collapse of the eruption column
produced numerous pyroclastic flows. As these hot pyroclastic flows reached the
ocean where they caused additional explosions. During these explosions, most of
the fine-fraction of the ash was removed. The eruption formed a caldera. An
estimated 92,000 people were killed by the eruption. About 10,000 direct deaths
were caused by bomb impacts, tephra fall, and pyroclastic flows. An estimated
82,000 were killed indirectly by the eruption by starvation, disease, and hunger.
The 1815 eruption of Tambora caused the "Year without a Summer." Daily minimum
temperatures were abnormally low in the northern hemisphere from late spring to
early autumn. Famine was widespread because of crop failures.
1883 KRAKATAU
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In the Sundra Strait, Indonesia
VEI=6
Since 1927, small eruptions have been
frequent and have constructed a new
island, Anak Krakatau (Child of Krakatau)
Earthquakes felt 5-6 years before
Began with mild ash/steam for 3 months for
perbuwatan
Ash-leden gas columns from perbuwatan
and danan
Smaller eruptions intensified and
culminated in the explosive eruption of
August 27th, 1883
Caused tsunami 140ft high
1991 PINATUBO
Philippines
 Thick layers of ash
completely surrounds
the crater and the effect
of mudflows in this
previously heavily
forested and agricultural
region can be traced as
ribbons flowing downhill
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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.
Types of Volcanoes
Three types of volcanoes:
•Cinder- pyroclastic fragments, rock fragments, cinder cone crater, central venthot gases and rock
•Shield- mostly lava flows
•Composite or Stratovolcano- (most important) alternates pyroclastic flows and
lava flows
Radiating dikes, pyroclastic layers.
Mt. St Helens
Mt. Rainer
Mt. Hood
Mt. Fuji
Mt. Pinatubo
Cont…
•Ice Volcanoes
•Mud Volcanoes
•Hot spot Volcanoes
Three distinctions of volcanoes:
•Active
•Dormant
•Distinct
Volcano Hazards:
• Lahars- quickly moving mixtures of rock and water – looks like
moving concrete
• Lava Flows- Streams of molten rock-magma that has come to earth’s
surface
• Pyrcoclastic Flows- high density mixtures of hot dry rock fragments
and hot gases
a. vent at high speeds
b. Gases- S02 (Sulfur dioxide) most important
c. irritates skin and mucous membranes
d. forms aerosols including H2SO4 (sulfuric acid) that can enter
stratosphere
• Tephra
Composition of Material erupted:
•63% or more silica, lava is felsic meaning that the volcano erupts
violently as domes or have short stubby flows. They form
stratovolcanoes.
•52-63% silica, lava is of intermediate composition, they generally occur
above subduction zones
•If the lava is less than 52% and greater than 45% silica, the lava is
called mafic because it has higher levels of magnesium. They usually
occur at mid ocean ridges where plates are pulling away from each
other.
EFFECTS ON THE PLANET
RELATED TO VOLCANOES
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Gases put in the air –Mt. Pinatubo’s estimated aerosol loading is 30 (Tg). Reached
an altitude of more than 30 (km) Injected gaseous sulfur dioxide into the
stratosphere. The sulfur dioxide gases transformed into sulfuric acid (H2SO4/H20)
aerosols. Mt. Pinatubo is estimated to have had one of the largest aerosol
perturbation to the stratosphere.
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Gaseous components: water vapor, sulfur dioxide, and hydrochloric acid.
Hydrochloric acid is dissolved quickly and rains out of the original cloud. Aerosols are produced
when the sulfur dioxide is transformed into sulfuric acid; which condenses into aerosols with low
saturation vapor pressure. These new aerosols increase the Earth’s Albedo by reflecting solar
radiation back into space. It also can warm the stratosphere by absorbing infrared radiation.
Occasional violent volcanic eruptions, such as Mt. Pinatubo, pump gases like sulfur dioxide and
aerosols high into the atmosphere where they can linger for more than a year, reflecting sunlight
and shading Earth’s surface. The cooling influence of this aerosol “shade” is greater than the
warming influence of the volcanoes’ greenhouse gas emissions, and therefore such eruptions
cannot account for the recent warming trend.
Another main gas is carbon dioxide- if excess carbon dioxide gets into the soil it will kill off
plants. Excess carbon dioxide is fatal to humans and animals so this affects the biosphere.
•Planetary Albedo—increased by volcano-cause cooling-Volcanic emissions
can change the amount of solar radiation received on
Earth’s surface. Emissions of SO2 gas react with moisture to produce
extremely small droplets (aerosols) of H2SO4 (sulfuric acid) which seed
water droplet in clouds and increase cloud albedo.
http://jack.pixe.lth.se/kfgu/KOO090_FKF075/Artiklar/P05.pdf
The aerosols affect the planetary albedo, which is how much light
gets reflected back from particles in the atmosphere, mainly the
stratosphere.
Volcanoes emit C02 into the stratosphere
There are factors in Earth’s climate system that influence how much
sunlight our world reflects back to space versus how much it catches
and stores in the form of heat. Any significant changes in the
brightness of the land surface or in the extent of clouds and aerosols in
the atmosphere affect how much sunlight Earth reflects, which, in turn,
affects the climate system.
Temperature•Aerosols may enter the Earth’s stratosphere and remain there for
many years until they are rained out. During this time Earth’s
average temperature may drop by 2⁰C or more, such as
happened following the eruption of Mt. Pinatubo in 1990 or Mt.
Tambora in 1815 (1816-1817 was called the “year without a
summer”).
Economy—money/resources:
The cost of an eruption of a volcano can be great. With the destruction of
nearby crops, the cost of food production has to be increased to pay for all the
damage done to the economy. Prices of goods go up and people end up
spending more than they would have before the eruption.
Do these alter the climate?
-Yes all these effects alter the climate in one way or the other. There isn’t a
one major cause to global cooling. All things in all the spheres of the earth
affect one another.
EFFECTS ON THE PLANET RELATED TO
VOLCANOES: ARCTIC OSCILLATION
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According to A Climate for Change Arctic Oscillation is, “s a winter climate pattern in the
Northern Hemisphere defined by difference in air pressure between mid latitude air pressure
and the air pressure over the Arctic.” When low pressure predominates in the Arctic, the winds
confine the extremely cold air and the Arctic Oscillation is called positive. When the pressure
system weakens, allowing the cold air to slide south and warmer air to gather in the Arctic, the
Arctic Oscillation is said to be negative.
Up until January, most of us hadn’t heard of the Arctic Oscillation which is currently
operating in the negative phase wherein the pressure system is weakening, the AO is
apparently responsible for the extreme cold weather from France to Florida, where manatees
and orange trees are dying in equal measure due to freezing weather.
Throughout December 2009, the North Atlantic Oscillation was strongly negative, said the
National Weather Service. This image shows the impact of the negative Arctic Oscillation on
surface temperatures throughout the Northern Hemisphere as observed by the NASA’s Terra
satellite. Cold Arctic air chilled the land surface.
The AO works in two phases, in the first phase the pressure is lower over the Arctic and higher
over the “middle” latitudes and the Arctic Ocean is colder. In the second phase, the negative
phase, the reverse is true and the Arctic Ocean is warmer, leading to more melting ice or less
ice coverage on land.