topics for today climate change: a global problem? quiz #7 (of 11)!!
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Topics for Today
Climate Change: A Global Problem?
Quiz #7 (of 11)!!
Readings for Today
3.8 Methane and other greenhouse gases
3.10 Responding to science with policy changes
3.11 The Kyoto Protocol on Climate Change
3.12 Global warming and ozone depletion
May even bleed into Monday.
Topics for Monday
Where does the Carbon Go? The Carbon Cycle
http://www.esd.ornl.gov/iab/iab2-2.htm
Readings for Monday
3.5 The Carbon Cycle
Announcements!!!
Announcements!!!
Bring back your
radon disks!!
Announcements!
Nice, warm
weather…Please
remember: Do not wear shorts
or sandals to lab!!
Topics for Today
Climate Change: A Global Problem?
Quiz #7 (of 11)!!
Review…
The Greenhouse Effect
Q: When will IR cause a
molecule to vibrate?
A: When there is a dipole moment!
Review
Dipole Moment: Unequal distribution of charge!
Does CO2 absorb IR radiation?
N2??
DEMO!!
CO2 N2
What makes greenhouse gases more
potent?
N2O
CFCs
HCFCs
HFCs
CH4
CO2
CH4
O3
H2O
1) Atmospheric Lifetime
2) Atmospheric Concentration
3) How efficiently can the molecule absorb IR?
1) Atmospheric Lifetime
2) Atmospheric Concentration
3) How efficiently can the molecule absorb IR?
CO2 bending and stretching…
SummarySymmetric Stretch
Asymmetric Stretch
Bend 1
Bend 2
CO2 has only 3
vibrations
CFCs
CFCs have at least 10 possible
vibrations!!
CFCs are much more efficient at trapping IR than
CO2.
This is due to the more
complicated SHAPE
1) Atmospheric Lifetime
2) Atmospheric Concentration
3) How efficiently can the molecule absorb IR?
4) WHERE it absorbs in
the IR range!!
Water Vapor Figure 3.16
Figure 3.15 in your Text
CO2
Figure 3.15 in your Text
CO2
What about the other gases?
Ab
sorp
tio
n %
Ab
sorp
tio
n %
Very little IR is absorbed from 8-12
micrometers!!
Reminder: This is 8,000-12,000 nm!!
This range is called the
“atmospheric window.”
Where do CFCs
absorb?
HCFC 132a
www.sstd.rl.ac.uk/srg/srgproj/ircfc/ircfc.htm
Micrometers?
HCFC 132a
www.sstd.rl.ac.uk/srg/srgproj/ircfc/ircfc.htm
MICROMETERS
2.817 10 57
CFCs (and replacements)
absorb directly in the atmospheric
window!!!
Where do CFCs
absorb?
At about 7-11 micrometers!
!
1) Atmospheric Lifetime
2) Atmospheric Concentration
3) How efficiently can the molecule absorb IR?
So, just how potent are the major GHGs?
4) WHERE it absorbs in
the IR range!!
Global Warming Potential (GWP)The ability for a gas to trap energy in the atmosphere. Based on an equal mass of CO2 over a specific time period.
Atmospheric Lifetime
(years)
Atmospheric Concentration (ppb) GWP Contribution
to Enhanced
Effect
CO2 60-100 370,000 1 60%
CH4 12 1750 23 20%
N2O 110 315 300 4%
CFC > 100 3 ~10,000 12%
http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/GWPs.html
GHGs are not the only thing in the atmosphere
that change the Earth’s energy balance!!!
Global Warming Potential (GWP)The ability for a gas to trap energy in the atmosphere. Based on an equal mass of CO2 over a specific time period.
Atmospheric Lifetime
(years)
Atmospheric Concentration (ppb) GWP Contribution
to Enhanced
Effect
CO2 60-100 370,000 1 60%
CH4 12 1750 23 20%
N2O 110 315 300 4%
CFC > 100 3 ~10,000 12%
http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/GWPs.html
What are the effects of the
enhanced greenhouse effect?
TEMPERATURE CHANGE
CO2 Concentration (ppm)
Greenhouse gases
correlate with warming!
http://hyperphysics.phy-astr.gsu.edu/hbase/solar/venusenv.html
Venus’ atmosphere is
about 97% CO2
The average temperature is about 900oF!
Runaway greenhouse
effect!
Very thin atmosphere; most of the CO2 is frozen in
the ground…
The average temperature is
about -60oF!
TEMPERATURE CHANGE
CO2 Concentration (ppm)
An increase of about 0.8oC over the past century!
So what if the Earth gets a
little warmer??
This is an average…
The big problem is NOT
necessarily the warming…
Greenhouse gases lead to more
energy trapped in the atmosphere.
The effects of this can can vary…
Overall, the Earth’s natural energy balance
is changed
What are the effects of increased energy in the atmosphere?
Spruce trees in the arctic
tundra…
Retreating Glaciers…
The Cascades
Illecillewaet Glacier, Glacier National Park.Photo Credit: Dr. Dan McCarthy, Brock University
Glacier National Park
“The park’s namesake glaciers will disappear in the next few decades.”
The snows of Kilimanjaro
3.9Figure 3.26
Slowing of ocean
currents… http://www-class.unl.edu/geol101i/15a_climate.htm
Changing the energy balance also…
Changes weather patterns
SO, What do we know?
1) GHGs are generally
increasing…
MethaneNitrous Oxide
CFCs and related
2) The Earth’s temperature is
rising…
1) GHGs are generally
increasing…
2) The Earth’s temperature is
rising…
And, now, for the 65 million dollar
question…
1) GHGs are generally
increasing…
2) The Earth’s temperature is
rising…
Are these related
?
Disagreement…
Handout.
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