Chapter 19
Global Warming &
Ozone Loss
© Brooks/Cole Publishing Company / ITP
Tuesday 3/29/11
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6)
Inconvenient Truth Review
Current Event – Global Warming & Coffee
Phet – Molecules & Light
Compare Global Warming & Ozone Loss
Sticky Analysis of CFCs & Skin Cancer
Compare Kyoto vs Montreal Protocols
Electromagnetic Spectrum
Black Body Radiation
Earth radiation magnified 500x
Infrared Absorbance of CO2
Infrared Absorbance of Water
Infrared Absorbance of CH4
Infrared Absorbance of N2O
Absorbance Simulation of Gases
http://phet.colorado.edu/en/simulation
/molecules-and-light
Table 18-1 Problem Comparison
Green House Effect Ozone Shield
Where in the
Atmosphere?
Troposphere 0-17
miles up
Stratosphere 11-30
miles up
What process
occurs?
Traps infrared (IR)
heat near surface
Filters ultraviolet
(UV) radiation
from the Sun
Oxygen O2, ozone
O3
What natural gases H2O, CO2,
are involved?
CH4 (methane)
What are important CO2, CH4, CFCs,
CFCs, halons,
human inputs?
N2O (nitrous oxide) CCl4, etc.
What problems
result?
Global warming,
rising sea levels
Ozone depletion,
skin cancers
International Reports
• http://www.ipcc.ch/ipccreports/assessments
-reports.htm
• IPCC Reports on Global Warning Issue
Activities
• Your Contribution to Global Warming
• Sea Level Rises – Topography
• An Inconvenient Truth
An Inconvenient Truth
It ain’t what you don’t know
that gets you into trouble,
it’s what you know that just
ain’t so.
Mark Twain
Green House Gases
1. What are greenhouse gases and what
processes produce them?
• 80% CO2 – burning fossil fuels
• CH4, methane – livestock manure,
• N2O, nitrous oxide – fuel burning, crop &
forest burning
• SF6, PFCs, HCFCs – industrial processes
Green House Effect
2. How do greenhouse gases cause global
warming?
• See page 28 & 29 of AIT
• Solar energy reaches the Earth.
• The Earth re-radiates some as infrared, IR.
• Green house gases like CO2 absorb IR
before it escapes and hold the energy in the
atmosphere.
• As green house gases accumulate in the
atmosphere, more & more energy is trapped
in the atmosphere.
Atmospheric CO2 Concentrations
(1 of 2)
3. Scientists have measured atmospheric CO2
concentration from 1958 to today. What has been the
trend in global atmospheric CO2 concentration over the
past 50 years since scientists started directly measuring
it?
• See page 36 & 37
• determine slope of steady increase
• m = (380-315)ppm/ (2005-1958)yr
• = 65/47 ppm/yr = 1.4 ppm/yr
• 381ppm in 2005 vs 280 ppm baseline, % increase?
• 381/280 = 136% or a 36% increase.
Atmospheric CO2 Concentrations
(2 of 2)
3. Why does the line go up and down each year?
See pages 32-35
• Most of the Earth’s land mass is in the Northern
Hemisphere.
• During the Spring & Summer the Northern Hemisphere
draws in CO2 during its growing season.
• During the Fall & Winter the Northern Hemisphere
releases CO2 as plants slow photosynthesis and a lot
decomposes.
• The Southern Hemisphere has a much smaller effect.
Historical CO2 vs Temperature
4. What is the relationship between global
atmospheric CO2 concentrations and mean global
atmospheric temperature over the past 600,000
years? Gore says this is like the fit of South
American and African continents; explain what he
means by this.
• See page 66 & 67.
• Antarctic ice core measurements show that global
temperatures closely mirror global CO2 levels.
Cyclical Pattern?
5. Explain the evidence that suggests that the warming
period we are in is not just part of a "natural cyclical
phenomenon".
• See page 64 & 65.
• Over the last 1000 years, glacial ice cores show 3
previous warming periods, none of them compare to the
present warming period in persistence or intensity.
• See page 67.
• The present CO2 levels far exceed any CO2 levels
measured over the past 650,000 years and they continue
to climb steeply.
Winston Churchill 1936
The era of procrastination, of half-measures, of
soothing and baffling expedients, of delays, is
coming to a close. In its place we are entering a
period of consequences.
What was he talking about?
Hitler’s Nazi Invasions
How does this relate to global warming?
The consequences of global warming are already
impacting our world.
Effects of Global Warming
A. Melting of floating sea ice & impacts
1. Minimal sea level change ( page 142 & 143)
• Only 1/8 of sea ice is above the sea level.
2. Polar bear populations (and others) page 147
• Polar bears depend on diminishing ice pack for seal
hunting grounds. They are drowning at record rates.
3. Acceleration of global warming due to changes in
sunlight reflection & absorption (see page 145)
• Sea ice reflects sunlight and minimizes absorption.
• Melted sea ice exposes sea water which absorbs
sunlight, heats up and melts the sea ice even faster in a
__________ feedback loop.
Outline
1. Natural Global Processes
• What is the greenhouse effect?
• What is the ozone shield?
2. What Problems Result from Human Inputs
• Global warming
• Ozone depletion
3. Solutions
4. Summary
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pollution – undesirable change in physical, chemical,
or biological characteristics of air, water, soil, or food
that can adversely affect humans or other living
organisms.
Fig. 18–3
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1. Natural Global Processes
• Greenhouse Effect
• Ozone Shield
• Questions
– What?
– Where?
– Gases involved?
– Human inputs?
– What problems
result?
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What is the Greenhouse Effect?
Greenhouse Effect: a natural process that traps heat
near the Earth’s surface.
• short wave
radiation in
• long wave
radiation out
• re-radiation
downward by
“greenhouse
gases” in
atmosphere
Fig. 4–7
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Human inputs?
c) CH4
(continued)
Greenhouse Effect:
• methane (CH4)
• nitrous oxide (N2O)
d) N2O
Fig. 19–2 c & d
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2. What Problems Result from
Human Inputs?
• Global Warming
• Ozone Depletion
• Questions
– Are they proven?
– What are potential
consequences?
– What can be done?
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How Does This Relate to
the Carbon Cycle?
• Sources of Increased Atmospheric CO2
– Burning Fossil Fuels
(see Fig. 5–5)
– Deforestation
• Carbon Balance: increased atmospheric CO2
less than expected based only on input
– about 49% remains in atmosphere
– about 29% uptake by oceans
– carbon balance: about 22% unaccounted for
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Consequences of Increased
Greenhouse Gases
Fig. 19–6
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Climate Changes
During Past 900,000 Years
Fig. 19–3
• Past climate based on study of Antarctic glaciers
• Cycles of Ice Ages lasting about 100,000 years
• Interglacial Periods lasting 10,000 to 12,500 yrs
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Climate During Past 160,000 Years
• End of last ice age
about 10,000 yr BP
• Now in warm
interglacial period
• Based on ice core
data, analysis of
trapped gas
• Correlation between
CO2 & mean
temperature
Fig. 19–4
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What is the Scientific Consensus?
• Mean global
temperature rose
about 0.6º C (1º
F) in past 100
years
• Increase is real,
not explained by
natural variation
in solar radiation
• Warming greater
at poles than
equator, greater
at night, mostly
Fig. 19–5
troposphere
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Future Scenarios
General Circulation Models (GMCs) used
to predict future climate
• Projected warming
of 1 to 3.5 º C
between 1990 &
2100
• Likely scenario:
doubling of CO2
(from 280 ppm to
560 ppm) before
2100 leading to
warming of 2º C
Fig. 19–5
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Role of Ocean
• Storage of CO2 in deep water
• Warming could decrease ability of ocean to serve
as “sink” for carbon
Fig. 19–7
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Ecological Implications
• Shift of habitat
to higher
latitudes
• Shift of habitat
to higher
elevations
• Potential large
loss of
biodiversity
Fig. 19–8
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3. Solutions
Solutions
to Global
Warming
Fig. 19–9
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Solutions
to Global
Warming
Fig. 19–10
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Human inputs?
a) CO2
Greenhouse Effect:
• carbon dioxide (CO2)
– 75% developed
countries
– 22% U.S.
b) CFCs
• chlorofluorocarbons
(CFCs)
Fig. 19–2 a & b
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Where?
• Greenhouse Effect:
• in troposphere
• Ozone Shield:
• in stratosphere 11-16
miles up
What is the Ozone Shield?
Ozone Shield: a natural process that filters
ultraviolet (UV) radiation before it reaches the
lower atmosphere.
Human inputs?
• Ozone Shield:
• Chlorofluorocarbons (CFCs)
• other stable halogen–containing gases (halogens =
chlorine, fluorine, & bromine)
b) CFCs
What Natural Gases?
•Greenhouse Effect:
water
H2O
carbon dioxide
CO2
methane
CH4
•Ozone Shield:
oxygen
O2
ozone
O3
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How Does Depletion Occur?
• CFCs stable, move from troposphere to
stratosphere
• UV breaks off chlorine molecule (Cl) from CFC
• Cl acts as a catalyst to break down ozone (O3)
– catalyst – promotes a chemical reaction without itself
being used up in the reaction
– shifts equilibrium of oxygen / ozone reaction:
O2
O3
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How Does Depletion Occur?
Fig. 19–12
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Consequences of Ozone Depletion
• Increase in skin cancer & cataracts,
especially in southern hemisphere
• More ozone near earth’s surface, produced
in photochemical smog – lung problems,
suppressed immune response, cancer
© Brooks/Cole Publishing Company / ITP
What are the Consequences of
Increased
Ozone Depleting Gases
What are the Consequences of
Ozone Depletion?
• Increase in skin cancer & cataracts,
especially in southern hemisphere
• More ozone near earth’s surface,
produced in photochemical smog – lung
problems, suppressed immune
response, cancer
What is the Ozone Hole?
• Seasonal thinning of the ozone layer has
resulted at the poles, especially in the
southern hemisphere.
• Recent models suggest the hole may not get
larger.
Comparing Ozone Loss
How does the ozone loss over the North Pole compare to the South
Pole?
Projected total ozone loss, averaged over 2010-2019, during
September for the Antarctic (left) and during March for the Arctic
(right).
According to the model used to make these projections, during this
period the severity of ozone loss over the Arctic may approach
that over the Antarctic.
Dark red represents ozone depletion of 54% or more; light blue, 1830%; dark blue, 6-12%.
Solutions to Ozone Depletion
• phase out use of ozone–depleting chemicals
– halons, CFCs, methyl chloroform, methyl
bromide
• phase in use of CFC substitutes
– non–halogen aerosol propellants,
hydrochlorofluorocarbons (HCFCs),
hydrofluorocarbons (HFCs), hydrocarbons
(HCs), ammonia, water & steam, terpenes,
helium
Summary Problem Comparison
Green House Effect Ozone Shield
Where in the
Atmosphere?
Troposphere 0-11
miles up
Stratosphere 11-30
miles up
What process
occurs?
Traps infrared (IR)
heat near surface
Filters ultraviolet
(UV) radiation
from the Sun
Oxygen O2, ozone
O3
What natural gases H2O, CO2,
are involved?
CH4 (methane)
What are important CO2, CH4, CFCs,
CFCs, halons,
human inputs?
N2O (nitrous oxide) CCl4, etc.
What problems
result?
Global warming,
rising sea levels
Ozone depletion,
skin cancers