Transcript Volcano Distribution - Cal State LA

Natural Causes of Climate Change
 Factors primarily responsible for most past
climate change:
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Variations in the Earth's orbital characteristics.
Atmospheric carbon dioxide variations.
Volcanic eruptions
Variations in solar output.
Volcanoes and Gases
 Volcanic gases significant impact on global
change
 Magma contains gases
 Concentrations vary between volcanoes
 Water vapor most abundant then carbon dioxide &
sulfur dioxide. Others = hydrogen sulfide, hydrogen
chloride, and hydrogen fluoride.
 Volcanic gas, aerosol droplets, and ash injected into
the stratosphere during major explosive eruptions.
 Sulfur dioxide, can cause global cooling, ozone
destruction, and volcanic smog or "vog".
Sulfur dioxide and Aerosols
 Major impact is conversion of sulfur dioxide to
sulfuric acid (H2SO4),
 condenses sulfate aerosols.
 aerosols increase reflection of radiation to space; cool
the Earth's lower atmosphere
 however, absorb heat radiated up from the Earth,
warming stratosphere.
 sulfate aerosols also help destroy ozone
 Chemical reactions produce chlorine monoxide (ClO), which
destroys ozone (O3).
Volcano Distribution
Volcano Types
 Non-explosive
 Fluid Basaltic Lava
 Basalt is rich in iron &
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Magnesium
Not rich in gases
High temperature
eruption
Broad Volcano
Examples--Hawaiian
Britannica
Explosive Volcano
 Rich in Silica
(SiO2)
 Rich in Gases
 Very Viscous
 Lower
Temperature
Eruptions
California Explosive Volcanoes
Shasta
Lassen
Sampling gases
Collecting Gas Samples at Mt.
San Helens
Sulphur dioxide measurements with
spectrometer. Mt San Helens
Types of volcanic gases
The most abundant gas typically released into the atmosphere from volcanic systems is
water vapor (H20), followed by carbon dioxide (C02) and sulfur dioxide (S02). Volcanoes
also release smaller amounts of others gases, including hydrogen sulfide (H2S),
hydrogen (H2), carbon monoxide (CO), hydrogen chloride (HCL), hydrogen fluoride (HF),
and helium (He).
Volcano
Tectonic Style
Temperature
Kilauea
Summit
Hot Spot
1170°C
Erta` Ale
Divergent
Plate
1130°C
Momotombo
Convergent
Plate
820°C
H0
37.1
77.2
97.1
C0
2
48.9
11.3
1.44
S0
2
11.8
8.34
0.50
H
0.49
1.39
0.70
CO
1.51
0.44
0.01
HS
2
0.04
0.68
0.23
HCl
0.08
0.42
2.89
2
2
HF
----0.26
Examples of volcanic gas compositions, in volume percent concentrations
(from Symonds et. al., 1994)
USGS
Mount Pinatubo
 Mount Pinatubo eruption, on June 12, 1991.
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one of largest eruptions of this century.
erupted over a cubic mile of rock material.
20- million ton sulfur dioxide cloud into stratosphere to 20 miles.
largest sulfur dioxide cloud observed since satellites in 1978.
Sulfate aerosol formed in stratosphere from sulfur dioxide; increased
the reflection of radiation into space.
 Earth's surface cooled in the three years following the eruption, by as
much as 1.3 degrees ( Fahrenheit scale)
 sulfate aerosols accelerated destruction of ozone.
 Some blamed Midwest floods and larger Antarctic ozone hole on Mt.
Pinatubo aerosols.
 some large historic eruptions followed temperature decreases. not
all large eruptions followed by temperature decreases,
Sulfur Dioxide-Pinatubo & El Chichon
Mt. Pinatubo
El Chichon
NOAA
www.geo.mtu.edu
Graphs of average
temperatures 5 years before
and 5 years after the listed
various volcanic eruptions.
Low temperatures always
occur after an eruption
(occurring at Month #0).
Graph “e.” is a composite of
the graphs a.–d. Graph “f.” is
the response to the most
recent Mt. Pinatubo eruption.
(From: Climate Research
Unit).
http://earthguide.ucsd.edu/
Tree Rings & Eruptions
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High density wood = warm
temperatures, and vice versa.
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A list of years characterized by low tree-ring densities, with the
name of the volcano eruption immediately preceding the treering event indicated in parentheses (n.d. = not determined).
lowest tree-ring densities
follow major eruptions
Largest eruption, Peru 1601,
caused severe economic
damage in Peru and its
neighbors took 150 years to
recover
Severe winters, late frost, and
cool summers follow major
eruptions. Lead to poor
harvest
Tambora eruptions = Europe
spent summer around the
fireplace in 1816, with frost in
July, followed by famine.
http://earthguide.ucsd.edu/
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Deccan Trap
formed between 60 and
68 million years ago,[2]
eruptions may have
lasted fewer than 30,000
years.
gases released may have
played a role in the
Cretaceous–Tertiary
extinction event,.
the original area covered
by the lava flows was as
large as 1.5 million km²,
approximately half the
size of modern India.
release of volcanic gases
"contributed to an
apparently massive global
warming. Some data point
to an average rise in
temperature of 8 °C (14
°F) in the last half million
years before the impact at
Chicxulub."[3]
Naggs & Raheem
Deccan Trap
 Cretaceous, associated with Dinosaur extinction
 Much gas in atmosphere, warmed planet
 More gas than by meteor impact thought to cause
extinction
Tathagata 'Ted' Dasgupta
The basalt layers in India's Deccan Traps could be used to store huge
amounts of carbon dioxide.
DINODIA IMAGES/ALAMY
Siberian Trap - Permian
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Permian about 250 mya-greatest extinction
Scant evidence for meteor impact
Gases from impact not enough for extinction
Gases from magma led to extinction?
Milankovitch Theory
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Climate change due to variations
in the earth's orbit - Milankovitch
Theory
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1) eccentricity cycle - the earth's
orbit around the sun is elliptical.
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the shape of the ellipse
(eccentricity) varies from less
elliptical to more elliptical back to
less elliptical and take about
100,000 years to complete this
cycle.
currently, we are in an orbit of low
eccentricity (near circular).
review - when are we closest to
the sun?
Data analysis for the last 800,000
years of deep-ocean sediments
show that ice coverage is a
maxima every 100,000 years
this matches the Eccentricity
cycle period
http://www.wwnorton.com/college/geo/ege
o/flash/18_2.swf
 Precession cycle  The earth wobbles
about it's axis of
rotation like a
spinning top
 one cycle = about
23,000 years
 in 11,000 years,
seasons will switch
times during year
and will be more
severe...., why?
http://www.wwnorton.com/college/geo/ege
o/flash/18_2.swf
Obliquity
 Tilt Cycle - Obliquity
 axis of earth’s rotation is tilted
23.5°
 However, value changes from
22.5° to a maximum of 24.5°
and takes 41,000 years to
complete
 at 22.5° the seasonal variation
will be greater/less?
 at 24.5° the seasonal variation
will be greater/less than
current?
http://www.wwnorton.com/college/geo/ege
o/flash/18_2.swf
 100K cycles evident
for climate change
Sunspots
 huge magnetic storms that
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show up as dark (cool) areas
on the suns surface
more sunspots = more energy,
= more energy on earth
warmer climate during a sun
spot maximum; cooler climate
during minimum.
what does a sun spot look
like?
sun spot period is about 11
years
Sunspot Cycles
 Sunspot minimum
1645-1715
 Period called “Little
Ice Age”
Images from Nasa
The solar disk seen by the Yohkoh soft-X-Ray imager, over
the time period 1991-1995 (left to right), spanning the
descending phase of cycle 23.
Source: http://www.heasarc.gsfc.nasa.gov
Solar irradiation is the amount of
energy from solar radiation hitting
earth’s surface.