Transcript GEOL 1130 Global Warming

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Global Warming
The Evidence
Potential for change?
 Can anthropogenic change
be separated from
natural change?
 Can the world collectively
decide to do something
about global carbon
dioxide emissions?
What causes Global
Warming?
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Addition of greenhouse gases to
atmosphere
Main culprit is CO2
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CS Fig. 17.19
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CS Fig. 17.20
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CS Fig. 17.23
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CS Fig. 17.18
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Bubbles in glacial
ice preserve
air of past centuries:
Tell us what CO2
concentrations
were like before
the industrial
revolution
Edmonds, 1999
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Longer records
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Global
Temperatures
projected to rise
3 to 9 °F
Edmonds, 1999
Consequences?
http://www.enviroweb.org/edf/in
dex.html
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CS Fig. 17.22
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Historical Data
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Change in surface
temperatures,
1979-1998
Change in free
atmosphere
(<5 miles)
temperatures,
1979-1998
Note: deep red is ~1 °F warmer, deep blue is ~1 °F cooler
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The debate rages
on!
Newspaper articles show
scientists do not all agree as to
whether the planet is currently
warming
The vast majority of scientists,
however, do agree that the
planet is warming due to
additions of greenhouse gases
to the atmosphere
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Natural Climate Change
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Natural Climate Change
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Cooling of the last 100 million
years, warming of the last 20,000
years well documented
Short term change (10’s to 1000’s
of years) less well documented
Short term change less well
understood
Role of oceans unclear
 Role of tides (1800 year cycle) just
coming into question

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The Sulfate “Fingerprint”
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Best evidence that recent
warming is anthropogenic
Three years in the
1990’s are the
warmest in the
Northern Hemisphere,
by far, of the last
400 years!
From Mann
and others,
Nature, 1998
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Where we stand:

 What we’re pretty
What we do know:
sure of:
 Atmospheric CO2
concentrations have
 Surface temps in
risen 50% since the
the Northern
beginning of the
Hemisphere are the
industrial revolution
highest they’ve
 With business as
been in 400 years
usual, CO2
 Climate models do
concentrations will
a good job of
continue to rise
predicting the
 CO2 is a strong
impact of CO2 rise
greenhouse gas
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What we’re not
sure of:

Surface temps
have risen
more in the
last 25 years
than they
would have
without CO2
increases
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Change in Minnesota
“Recent research indicates a warming trend
in Minnesota. A study of the climate record at
Fort Snelling shows an increase of 2.9°F in
average annual temperature between the
1860s and 1987, almost three times the
worldwide average. Analyses of more than a
hundred temperature-depth profiles in North
America show that ground latitudes
comparable to Minnesota’s indicated ground
warming of up to 3.6°F.”
From “Playing with Fire, Global Warming in
Minnesota” 1999; data from Baker and Skaggs, 1989
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MN Biomes at risk
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Change in Lake Superior
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CS, page 390
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Edmonds, 1999
Bush Rejection
of Kyoto Protocol
May 2001
USA
Europeans angry
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CS Fig. 17.23
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FCCC
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The ultimate objective of the
Convention … is to achieve…
stabilization of greenhouse gas
concentrations in the atmosphere
at a level that would prevent
dangerous anthropogenic
interference with the climate
system.
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Edmonds, 1999
Developed and transitional countries
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Kyoto Protocol:
Annex 1 countries reduce
emissions by average of 5.2%
Edmonds, 1999
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The End
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