Transcript WFSC 420 Chapter 21

Environmental Science: Toward a
Sustainable Future
Richard T. Wright
Chapter 20
The Atmosphere: Climate, Climate
Change, and Ozone Depletion
PPT by Clark E. Adams
El Niño: What Happened?
April
May
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June
Jet streams
shifted from
normal course
Cause unknown
The El Niño Effects: Fig. 20-1
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Landslides on the California coast
Mildest hurricane season in many years
Rain five times normal in an East Africa
drought region
Record crop harvests in India, Australia,
and Argentina
La Niña: What Happened?
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Easterly trade winds reestablished with
greater intensity
Upwelling of colder water from ocean
depths
Jet streams are weakened
Global patterns in moisture and
evaporation return to “normal”
Atmospheric Structure
Weather: Solar Energy Balance
Most solar energy absorbed by atmosphere,
oceans, and land
Weather: Convection Cell
Tornadoes
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Cold low-pressure
air mass collides
with a warm highpressure air mass
http://www.photolib.noaa.gov/nssl/nssl0065.htm
Fujita Scale Measures the Intensity of
Tornadoes
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F-0: 40–72 mph, chimney damage, tree
branches broken
F-1: 73–112 mph, mobile homes pushed off
foundations or overturned
F-2: 113–157 mph, considerable damage,
mobile homes demolished, trees uprooted
Fujita Scale Measures the Intensity of
Tornadoes
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F-3: 158–205 mph, roofs and walls torn down,
trains overturned, cars thrown
F-4: 207–260 mph, well-constructed walls
leveled
F-5: 261–318 mph, homes lifted off foundation
and carried considerable distances, autos
thrown as far as 100 meters
Climates in the Past
Ocean and Atmosphere
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Covers 75% of the Earth’s surface
Major source of water to hydrologic cycle
Major source of heat to atmosphere
Stores and conveys heat
The Ocean Conveyor System
The Earth as a Greenhouse
Factors Affecting Global Temperatures
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Cloud cover: cooling
Changes in Sun’s intensity: cooling or
warming
Volcanic activity: cooling
Sulfate aerosols: cooling
Atmospheric CO2 Concentrations
Global Surface Temperatures
Global Carbon Cycle
Impacts of Global Warming
Melting of polar ice caps
 Flooding of coastal areas
 Massive migrations of people
inland
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Evidences of Climatic Change
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17 of the hottest years on record have
occurred since 1980 (Fig. 20-5)
Wide-scale recession of glaciers
Sea level rising
Predicted mean global temperature change
by 2100 is between 1.5 and 4.5oC
Responses to Climate Change
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Response 1: mitigation = reduce CO2
emissions
Response 2: adaptation = accepting and
learning to live with the consequences of
climate change
Framework Convention on Climate
Change (FCC)
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Relied on voluntary approach to reduce
CO2 emissions
Developing countries continue toward
developed nation status using fossil fuels
Framework Convention on Climate
Change (FCC)
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To achieve a 7% reduction by 2010
requires a 25% reduction of present use
By 2010 CO2 emissions will have
increased by 30%
Framework Convention on Climate
Change (FCC)
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Bottom line: need 60% reduction (144
ppm) in CO2 emission worldwide NOW
to stabilize greenhouse gas
concentrations at today’s levels
Depletion of Ozone Layer
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Radiation and importance of the shield
Formation and breakdown of the shield
Coming to grips with ozone depletion
Good Ozone!
Bad Ozone!
Electromagnetic Spectrum
Formation of the Ozone Shield
Reaction #1: UV light + O2
O+O
Reaction #2: Free O + O2
O3
Reaction #3: Free O + O3
O2 + O 2
Reaction #4: UV light + O3
O + O2
Breakdown of Ozone Shield
Reaction #5: CFCl3 + UV
Cl + CFCl2
Reaction #6: Cl + O3
ClO + O2
Reaction #7: ClO + ClO
2 Cl + O2
Which reaction releases Cl from CFCs?
Which reaction generates more Cl?
Chlorine is a catalyst that destroys
the production of ________?
Montreal Protocol
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1987 – scale back CFC production by
50% by 2000
Coming to Grips with Ozone
Depletion: Montreal Protocol
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1990 – amendment to completely phase
out ozone-destroying chemicals by
2000
1992 – amendment to completely phase
out ozone-destroying chemicals by
1996
Why the rush?
Ozone Hole: 11 million sq.mi.
The Clean Air Act of 1990: Title IV
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Restricts production, use, emissions,
and disposal of ozone-depleting
chemicals
Regulates the servicing of refrigeration
and air-conditioning units
“Protecting Stratospheric Ozone”
Greenhouse Gases
Where
Type of Light
Chemicals
What’s the
big deal?
Major Law
How do we
fix it?
Ozone
End of Chapter 20