Zachary Oswald, Charlene Bentum, Guy Duncan
Spring 2010 ESCI 580- Teaching Middle School Earth System Science using
Problem Based Learning
Assignment: Mt. Pinatubo Module- Cycle B Group Discussion/Team Model Building
Document
Date Due: 03/07/2010
Problem Statement
When volcanoes erupt, the event puts into the atmosphere numerous particles and gases.
What are these particles and gases, how much do they affect the planet, and is the
resulting cooling something that we can learn from and utilize to reduce Global
Warming?
Introduction
According to the U.S. Geological Survey (USGS), the world’s volcanoes, both on land
and undersea, generate about 200 million tons of carbon dioxide (CO2) annually, while
our automotive and industrial activities cause some 24 billion tons of CO2 emissions
every year worldwide. Despite the arguments to the contrary, the facts speak for
themselves: Greenhouse gas emissions from volcanoes comprise less than one percent of
those generated by today’s human endeavors. (E>A)
Do Volcano Eruptions Alter the Climate/Cause Global Cooling? (The Why)
Some scientists believe that spectacular volcanic eruptions, like that of Mt. St. Helens in
1980 and Mt. Pinatubo in 1991, actually lead to short-term global cooling, not warming,
as sulfur dioxide (SO2), ash and other particles in the air and stratosphere reflect some
solar energy instead of letting it into Earth’s atmosphere. SO2, which converts to sulfuric
acid aerosol when it hits the stratosphere, can linger there for as long as seven years and
can exercise a cooling effect long after a volcanic eruption has taken place. Scientists
tracking the effects of the major 1991 eruption of the Philippines’ Mt. Pinatubo found
that the overall effect of the blast was to cool the surface of the Earth globally by some
0.5 degrees Celsius a year later, even though rising human greenhouse gas emissions and
an El Nino event (a warm water current which periodically flows along the coast of
Ecuador and Peru in South America) caused some surface warming during the 1991-1993
study period. (E>A>L)
Volcanic Gasses and Earth’s Atmosphere (The How)
There are many harmful gases that are produced and emitted into the atmosphere
during volcanic activities. These gases are mostly comprised of water vapor, carbon
dioxide, sulfur dioxide, fluorine, and chlorine. 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), (CO), hydrogen chloride (HCL),
hydrogen fluoride (HF), and helium (He) (L>E<A)
Volcano
Tectonic Style
Temperature
Kilauea Summit
Hot Spot
1170°C
Erta` Ale
Divergent Plate
1130°C
Momotombo
Convergent Plate
820°C
H20
37.1
77.2
97.1
C02
48.9
11.3
1.44
S02
11.8
8.34
0.50
H2
0.49
1.39
0.70
CO
1.51
0.44
0.01
H2S
0.04
0.68
0.23
HCl
0.08
0.42
2.89
HF
---
---
0.26
Examples of volcanic gas compositions, in volume percent concentrations (from Symonds
et. al., 1994)
The impurities within the water vapors are harmful and often misconceived as
nonthreatening. Carbon dioxide is the leading contributor pertaining to Global Climate
Change by means of the Greenhouse Effect. Sulfur dioxide can have a effect on the
weather and the environment. Large-scale volcanic activity may last only a few days, but
the massive outpouring of gases and ash can influence climate patterns for years. Sulfuric
gases convert to sulfate aerosols, sub-micron droplets containing about 75 percent
sulfuric acid. Following eruptions, these aerosol particles can linger as long as three to
four years in the stratosphere. This leads to the formation of acid rain, which causes
serious environmental problems. This aerosol blocks the sun and causes cooler
temperatures globally. The sulfur dioxide eventually depletes, but is replenished by each
subsequent eruption rich in sulfur dioxide. Hydrogen fluoride, carbon monoxide, and
hydrogen sulfide gasses can be a deadly to animals after an eruption. Fluorine and
chlorine molecules from the gases tend to condense in rain and coat grasses and plants.
This causes animals to become “poisoned” when they eat the fluorine-coated grass and
plants. Chlorine gasses are emitted as hydrochloric acid into the atmosphere. Carbon
monoxide, chlorine, and fluorine gaseous compositions contribute to other detrimental
effects in the atmosphere (E2>A>H<B>E1). Combinations of hydrogen chlorine and
hydrogen fluorine affect the ozone layer. The ozone layer of our Earth’s atmosphere
protects the DNA of plants and animals by blocking harmful ultraviolet rays emitted from
our Sun. (E1>A<L)
How long do volcanic events alter the Earth's Climate?
A volcanic eruption can affect the Earth’s climate short-term and long-term. The degree
to which the climate is affected has many factors including the “amount of gas a volcano
emits into the atmosphere, whether the gas is injected into the troposphere or
stratosphere, and the regional or global wind and weather pattern that disperses the gas”
(United States Geological Survey). Another factor affecting scientists’ abilities to track
the effects of volcanic eruptions is the near impossibility of measuring gas output of the
volcano (E>A). Aircraft can track some of the output, put their safety is compromised by
flying to low and close to the volcano, decreasing the accuracy of data collected.
Volcanic magma releases dissolved gases into the atmosphere during a volcanic eruption.
Magma, however, can still release gases into the atmosphere when it is underground,
through the soil (United States Geological Survey). This could increase the longevity of
the effects of volcanic gases. Therefore, it is hard to predict how long volcanic eruptions
will affect the environment and climate.
Despite the variances in volcanic effects, there are some general conclusions that can be
drawn about the long-term effects. Eruptions are though to have a large impact on global
cooling that occurs several years after a major eruption (E>A). For two years following
the eruption of Mt. Pinatubo in 1991, global temperatures dropped on average about one
degree Fahrenheit (Exploring the Environment). “The amount and global extent of the
cooling depend on the force of the eruption and, possibly, its latitude” (NASA Facts on
Line). Volcanic eruptions can cause temperatures around the world to decrease if the
eruption is large enough. The eruption of El Chichn in 1982, however, had little effect on
global temperatures. This could have been because of the occurrence of El Nino the
same year, which cancelled out the effect of the El Chichn eruption (NASA Facts on
Line) (E1>A, E2>A).
Short-term effects may be easier to measure because there are not as many factors to
consider. Sulfur dioxide can have a short term global cooling effects (E>A). Fluorine,
which is also emitted during an eruption, “can be a deadly to animals after an eruption. It
tends to condense in rain and coat grasses and plants. The fluorine is poisonous to
animals that eat the fluorine-coated grass and plants”.
(http://www.umich.edu/~gs265/society/volcanoes.htm) The short-term effects seem to be
more intense, perhaps because of the fact that “a few years after an eruption most of the
aerosol clouds will have decayed so that their effects on radiation will become
negligible” (NASA Facts 3). The diagram below shows the products of an eruption.
Depending on the amount of products emitted as well as the air currents, the effects, both
short and long term, will be altered.
Figure 1. Volcanism studies are an important aspect of climate research (see chemistry
glossary). Retrieved 6 March 2010 from NASA Facts: The Earth Science Enterprise
Series.
Geo-engineering (The Why)
Geo-engineering has been proposed as a possible mitigation for Global Climate Change
(Caldeira and Govindasamy, Teller and Wood). But can geo-engineering our environment work? We have already been conducting a large-scale experiment by pumping
uncontrolled amounts of CO2 into our atmosphere, and the results it seems are in. The
results are not without detractors, as would be the product of any uncontrolled testing.
But the natural eruption of Mt. Pinatubo of June 12-15, 1991 seems to back up the geoengineering possibilities. The eruption threw tons of sulfur dioxide into the upper
atmosphere, resulting in a temporary global temperature drop of 1 degree F.
(E>A>B/A/L/H)
So if we are already geo-engineering our environment, why not entertain mitigating
options? One thing that may not be an option is doing nothing. And the idea is not a new
one (David W. Keith, University of Calgary, Alberta).
Geo-engineering (The How)
Sulfur dioxide is a by-product of coal burning (ironically a greenhouse gas producer).
Unfortunately, the released sulfur gases are too low in the atmosphere, and have a very
short lived suspension in the low atmosphere. One possible model for utilizing sulfur
dioxides/sulfur compounds looks like this.
http://www.wired.com/science/planetearth/magazine/16-07/ff_geoengineering?currentPage=all
Sulfur compounds are collected from smoke stacks of coal burning power plants(1),
specially modified aircraft/spacecraft transport the compounds into the stratosphere
where they are released(2), the sulfur dioxide combines with Hydrogen to form sulfuric
acid which in turn combines with water to form a vast reflective network(3), bouncing
back 1-3 percent of solar radiation reaching the Earth(4). Using this process, geoengineers could create a Pinatubo like effect at will, and repeat it as needed to cool the
Earth.
References:
Kirchner, I., G. Stenchikov, H.-F. Graf, A. Robock. J. Antuna, Climate model simulation
of winter warming and summer cooling following the 1991 Mount Pinatubo volcanic
eruption, J. Geophys. Res., 104, 19,039-19,055, 1999.
Stenchikov, Georgiy L., Ingo Kirchner, Alan Robock, Hans-F. Graf, Juan Carlos Antuna,
R. G. Grainger, Alyn Lambert, and Larry Thomason, 1998: Radiative Forcing from the
1991 Mount Pinatubo volcanic eruption. J. Geophys Res. 103(D12), pp. 13837-13857.
Wolfe, Jason . "Volcanoes and Climate Change (DAAC Study) : Feature Articles." NASA
Earth Observatory : Home. N.p., 5 Sept. 2000. Web. 4 Mar. 2010.
<http://earthobservatory.nasa.gov/Features/Volcano/>.
Kunzig, Robert- Geoengineering: How to Cool Earth--At a Price, Scientific American
Magazine, November 2008
http://www.wired.com/science/planetearth/magazine/16-07/ff_geoengineering?
currentPage =all
http://www.theatlantic.com/magazine/archive/2009/07/re-engineering-the-earth/7552/
http://esseacourses.strategies.org/private/learner.module.php?course_id=295&coursemod
ule_id=716&cycle=A&cycle_label=7
<http://www.umich.edu/~gs265/society/volcanoes.htm> Retrieved 6 March 2010.
“Volcanoes and Climate.” Exploring the Environment: Volcanoes. Retrieved 6 March
2010. http://www.cotf.edu/ete/modules/volcanoes/vclimate.html
“Volcanoes and Global Climate Change.” NASA Facts: The Earth Science Enterprise
Series. Retrieved 6 March 2010.
<http://www.gsfc.nasa.gov/gsfc/service/gallery/fact_sheets/earthsci/eos/volcanoes.pdf>
“Volcanoes and Global Cooling.” NASA Facts on Ling: NASA Goddard Space Flight
Center. Retrieved 6 March 2010.
<http://www.gsfc.nasa.gov/gsfc/service/gallery/fact_sheets/earthsci/volcano.htm>
“Volcanic Gases and Their Effects.” United States Geological Survey. Retrieved 6
March 2010. <http://volcanoes.usgs.gov/hazards/gas/index.php>
Useful Sites for Teachers:
http://volcanoes.usgs.gov/about/
http://crystalinks.com/volcanoes.html
http://climate.gsfc.nasa.gov/index.php
http://www.ncar.ucar.edu/feature/fieldguides/permafrost/
http://passporttoknowledge.com/polar-palooza/wmv/healy03a.php
http://www.photolib.noaa.gov