Download Volcanoes and Climate

Volcanoes and Climate
by Laura Kammerdiener, Section AD
and Maggi Little, Section AD
What happens when volcanoes
erupt?
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Mount Pinatubo, June 13, 1991 (Image courtesy
of NOAA) – image from
http://earthobservatory.nasa.gov/Features/Volca
no/
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“Volcanologists believe that the
balance of the earth's mild climate
over periods of millions of years is
maintained by ongoing volcanism.”
(VC)
Gases and solids injected into the
stratosphere circled the globe for three
weeks (VCC)
Large-scale volcanic activity may last
only a few days, but the massive
outpouring of gases and ash can
influence climate patterns for years
(VCC)
Following eruptions, the aerosol
particles of the volcano can linger as
long as three to four years in the
stratosphere. (VCC)
Notes to Slide 1:
What happens when volcanoes erupt?
• The aerosol particles released during volcanic eruptions
causes a cooling effect where those particles are present.
• In the stratosphere, aerosol particles are capable of masking
the effects of warming caused by anthropogenic green house
gasses—but more on that when we discuss Slide 3.
• Objects projected into the atmosphere as a product of
eruptions is then mixed and distributed through the
atmosphere, spreading aerosols throughout the entire
atmosphere—so cooling due to volcanic eruptions is not
isolated around the volcano itself, rather it is spread across
the globe.
Sources for this slide:
•Volcanoes and Climate Change (VCC) http://earthobservatory.nasa.gov/Features/Volcano/
•Volcanoes and Climate (VC) http://www.cotf.edu/ete/modules/volcanoes/vclimate.html
What effects do volcanic eruptions
have on climate?
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“The effect of the volcanic gases and dust may warm or cool the earth's surface, depending
on how sunlight interacts with the volcanic material.” (VC)
– “Volcanoes that release large amounts of sulfur compounds like sulfur oxide or sulfur
dioxide affect the climate more strongly than those that eject just dust.” (VC)
EXAMPLE: When Mount Pinatubo erupted in the Philippines June 15, 1991, an estimated 20
million tons of sulfur dioxide and ash particles blasted more than 12 miles (20 km) high into
the atmosphere. The eruption caused widespread destruction and loss of human life. (VCC)
The red color indicates the sulfur cloud.
Rather, it is the concentration of the
sulfur cloud—the red indicates higher
presence of sulfur than the yellow
surrounding it.
“For many months, a satellite tracked the sulfur cloud produced by
Pinatubo. The image shows the cloud about three months after the
eruption. It is already a continuous band of haze encircling the entire
globe” (VC) [image via GOES Image: Courtesy of GSFC/NASA.
http://www.cotf.edu/ete/modules/volcanoes/vclimate.html]
Notes to Slide 2:
What effects do volcanic eruptions have on climate?
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While we spoke about cooling in the previous slide, sometimes heating
happens. However, typically the presence of aerosols in the atmosphere as
a direct result of volcanic eruption generally causes a temporary cooling
effect on Earth’s surface.
The temporary cooling trend contrasted with the example below the image
demonstrates that heating and cooling are not mutually exclusive—some
areas can experience heating, and others cooling, creating an overall global
trend of temperature cooling (due to the effect of the aerosols released in
the atmosphere) in spite of serious temperature increases in some areas.
The satellite image shows the sulfur cloud produced by Pinatubo in the
Philippines in 1991, about three months after the eruption. Earth’s winds
carry the sulfur cloud—originally more concentrated around the volcano—
throughout the atmosphere, spreading the sulfur cloud all the way around
the globe and making these temperature contrasts possible.
Sources for this slide:
•Volcanoes and Climate Change (VCC) http://earthobservatory.nasa.gov/Features/Volcano/
•Volcanoes and Climate (VC) http://www.cotf.edu/ete/modules/volcanoes/vclimate.html
How does this pertain to Global
Warming?
“Volcanic dust blasted into the atmosphere causes temporary
cooling.” Smaller particles of dust and ash are projected into the
lower atmosphere. These particles to not last long in the
atmosphere and the cooling they produce is minimal and short.
“However, dust tossed into the dry upper atmosphere, the
stratosphere, can remain for weeks to months before they finally
settle. These particles block sunlight and cause some cooling over
large areas of the earth.” (VC)
“Over long periods of time (thousands or millions of years),
multiple eruptions of giant volcanoes, such as the flood basalt
volcanoes can raise the carbon dioxide levels enough to cause
significant global warming. (VC)
The CO2 emitted into the atmosphere by the eruption of a
volcano is usually counteract by the cooling provided as a result of
particles injected into the stratosphere (the haze effect)” (CE)
Image of Pinatubo Eruption, via http://www.unepwcmc.org/information_services/publications/MountainWatch_Bi
shkek/presspack/
“The haze effect often generates exceptionally red
sunsets due to the scattering of red wavelengths by
submicron-size particles in the stratosphere and upper
troposphere” (CE)
Notes to Slide 3:
How does this pertain to Global Warming?
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Wikipedia Definition of “flood basalt”: A flood basalt or trap basalt is the
result of a giant volcanic eruption or series of eruptions that coats large
stretches of land or the ocean floor with basalt lava. Flood basalts have
occurred on continental scales (large igneous provinces) in prehistory,
creating great plateaus and mountain ranges
http://en.wikipedia.org/wiki/Flood_basalt
We should not consider any carbon dioxide emitted into the atmosphere
by eruptions to be of concern—at least as regarding the heating effects of
Global Warming. The effects of the amount of CO2 emitted into the
atmosphere by the volcano can be negated by the cooling effect of the
aerosols.
We would like to suggest that the cooling effects of volcanic eruptions can
help to mask the effects of an overall heating trend for the global average
surface temperature, but they do not negate them. Aerosols usually
account for the CO2 emitted by eruptions—this amount of aerosols
certainly cannot counteract the effects of Global Warming!
Sources for this slide:
•Volcanoes and Climate (VC) http://www.cotf.edu/ete/modules/volcanoes/vclimate.html
•Climate Effects of Volcanic Eruptions (CE) http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html
•“Flood Basalt” – Wikipedia http://en.wikipedia.org/wiki/Flood_basalt