Download WFSC 420 Chapter 21 - Streetsboro City Schools

Richard T. Wright
Environmental
Science
Tenth Edition
Chapter 20
The Atmosphere:
Climate, Climate Change,
and Ozone Depletion
Copyright © 2008 Pearson Prentice Hall, Inc.
Hurricane Katrina in Gulf of
Mexico (August 28, 2005)
The Atmosphere: Climate, Climate Change,
and Ozone Depletion
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Atmosphere and weather
Climate
Global climate change
Response to climate change
Depletion of the ozone layer
Atmosphere and Weather
• Atmospheric structure
• Weather
Atmospheric Structure
Some Terms
• Weather: day-to-day variations in
temperature, air pressure, wind, humidity,
and precipitation – all mediated by the
atmosphere
• Climate: result of long-term weather
patterns in a region
• Meteorology: scientific study of weather
and climate
Weather: Solar Energy Balance
Most solar energy absorbed by atmosphere,
oceans, and land
Weather: Convection Cell
Tornadoes
• Cold low pressure
air mass collides
with a warm high
pressure air mass
http://www.photolib.noaa.gov/nssl/nssl0065.htm
Fujita Scale Measures the Intensity of
Tornadoes
• 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
• 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
Climate
• Climates in the past
• Ocean and atmosphere
Climate
• Also defined as the average trend in
temperature and rainfall that produces a unique
assemblage of plants and animals
• On the next slide identify climates A to E, e.g.,
low average rainfall and high average
temperature = hot desert
High
Identify Climates A to E
A
D
C
B
E
Low
High
Precipitation
Climates in the Past
Past Climates
El Niño: What Happened?
April
June
May
• Jet streams
shifted from
normal course.
• Cause unknown.
El Niño: What Happened?
• Development of warm water in the
eastern Pacific over time.
• Reversal in trade winds that normally
blow from an easterly direction.
El Niño: What Happened?
• Warm water spread to the east.
• Global patterns in moisture and
evaporation changed = climate shifts.
The El Niño Effects
• 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?
• Easterly trade winds re-established with
greater intensity
• Upwelling of colder water from ocean
depths.
• Jet streams are weakened
• Global patterns in moisture and
evaporation return to “normal”
Ocean and Atmosphere
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Covers 75% of the Earth’s surface
Major source of water to hydrological cycle
Major source of heat to atmosphere
Stores and conveys heat
The Oceanic Conveyor System
The Ocean Conveyor System
• Thermohaline circulation: effects that
temperature and salinity have on density
of water
– Conveyor system moves water masses from
the surface to deep oceans and back again
– Cool northern waters more dense and sink to
depths of 4,000 m = North Atlantic Deep
Water (NADW)
The Ocean Conveyor System
– Deep water spreads southward to south
Africa and joined by cold Antarctic waters
– Spread northward into Indian and Pacific
oceans as deep currents
– Current slows down, warms up, becomes less
dense, rises to the surface and moves back to
North Atlantic
– Produces a warm climate in Europe
The Ocean Conveyor System
• Factors that could alter the conveyor
system.
– Appearance of unusually large quantities of
fresh water – melting icebergs
– Global warming
Global Climate Change
• The Earth as a greenhouse
• The greenhouse gases
• Evidence of climate change
The Earth as a Greenhouse
Factors Affecting Global Temperatures
• Cloud cover: cooling
• Changes in sun’s intensity: cooling or
warming
• Volcanic activity: cooling
• Sulfate aerosols: cooling
Greenhouse Gases: CO2 Emissions
from Fossil Fuel Burning
• 35% higher than before industrial
revolution
• Oceans = CO2 sink
• Forests = CO2 source
• 24 billion metric tons CO2 added each
year
Other Greenhouse Gases and Sources
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Water vapor
Methane
Nitrous oxide
CFCs and other
halocarbons
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Hydrological cycle
Animal husbandry
Chemical fertilizers*
Refrigerants*
* = Long residence times contribute to
ozone depletion
Intergovernmental Panel of Climate Change
(IPCC): Fourth Assessment
• Assess scientific issues
• Evaluate the impact of global climate
change and prospects for adapting to it
• Investigate ways of mitigating the effects
IPCC Assessments
• Third Assessment: Human activities are
influencing global climate change
• Fourth Assessment:
– global climate change is now occurring
– caused by rising levels of anthropogenic
greenhouse gases
– global impacts will be unprecedented and
severe
Evidences of Climatic Change
• 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 4.5 Co
Fourth Assessment CO2 Concentrations
Sources of CO2 Emissions
Global Carbon Cycle
Radiative Forcing
Heat Capture by the Ocean
Global Mean Sea Level
Muir Glacier in the Past
Muir Glacier Today
Impacts of Global Warming
• Melting of polar ice caps
• Flooding of coastal areas
• Massive migrations of people
inland
Impacts of Global Warming
• Alteration of rainfall patterns
• Deserts becoming farmland and
farmland becoming deserts
• Significant losses in crop yields
Reducing CO2 Emissions (True or
False)
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Reducing use of fossil fuels
Adopt a wait-and-see attitude
Develop alternative energy sources
Plant trees
Examine other possible causes of global
warming
Reducing CO2 Emissions (True or
False)
• Make and enforce energy conservation
rules
• Rely on the government
• Adopt the precautionary principle
• Raise the minimum driving age to 18 years
Key Findings of the Fourth Assessment
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Increased warming – climate change
Differing regional impacts
Heat waves more frequent and last longer
Vulnerable ecosystems - arctic
Widespread water concerns – increase in
extremes (+ and -) of daily precipitation
Key Findings of the Fourth Assessment
• Agriculture largely unaffected
• Thermohaline conveyor system expected
to slow down
• Rising sea levels
• Storm intensities expected to increase
Arctic Climate Impact Assessment
• Arctic climate is now warming rapidly
• Arctic warming and its consequences will
have worldwide implications
Arctic Climate Impact Assessment
• Arctic vegetation zones will shift, and
animal ranges and distribution will change
• Reduced sea ice likely to increase marine
transport and access to resources
• Thawing ice will disrupt transportation,
buildings, and other infrastructure
Decline of Arctic Sea Ice
Arctic Albedo Feedback
What About the Antarctic?
• Holds most of the world’s ice
– Could be a huge factor in future sea level rise
– Greenland and Antarctic ice sheets hold
enough water to raise sea level by 230 feet
• Losing as much as 36 cubic miles of
ice/year – enough to raise sea level by
0.4mm/year
Response to Climate Change
• Response 1: mitigation = reduce CO2
emissions
• Response 2: adaptation = accepting and
learning to live with the consequences of
climate change
Response I: Mitigation
• Framework Convention on Climate
Change
• Kyoto Protocol
• U.N. Climate Control Conference
• U.S. Policy
– Global Climate Change Initiative
– Climate Change Science Program
– National Climate Change Technology
Initiative
Response 2: Adaptation
• Reduced crop yields
• Water scarcity
• Increased heat and moisture = > infectious
diseases and lethal heat waves
• Increased intensity and severity of storm
events
• Impoverished nations will be most affected
– adaptation not an option
Depletion of Ozone Layer
• Radiation and importance of the shield
• Formation and breakdown of the shield
• Coming to grips with ozone depletion
Good Ozone!
Bad Ozone!
Electromagnetic Spectrum
Radiation and Importance of the Shield
• Skin cancer (700,000 new cases each
year)
• Premature skin aging
• Eye damage
• Cataracts
• Blindness
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
Chlorofluorocarbons (CFCs)
• Organic molecules in which both chlorine and
fluorine atoms replace some of the hydrogen
atoms.
• Sources:
– refrigerators and air conditioners
– production of plastic foam
– cleaner for electronic parts
– pressurizing agent in aerosol cans
Breakdown of Ozone Shield
Reaction #5: CFCl3 + UV
Cl + CFCl2
Reaction #6: Cl + O3
ClO + O2
Reaction #7: ClO + ClO
2Cl + O2
Which reaction releases Cl from CFCs?
Which reaction generates more Cl?
Chlorine is a catalyst that destroys
the production of ________?
Coming to Grips with Ozone Depletion
• Montreal Protocol: scale CFC
production back 50% by 2000
• Most industrialized countries no
long produce or use CFCs
Ozone Loss and Extent of Ozone Hole
Ozone Hole: 11 million sq.mi.
Ozone-depleting substances production and
presence in the atmosphere: past, present,
and future
CFCs
HCFCs
Relative abundances of chlorine and bromine
in the stratosphere
The Clean Air Act of 1990: Title IV
• Restricts production, use, emissions,
and disposal of ozone-depleting
chemicals.
• Regulates the servicing of refrigeration
and air-conditioning units.
“Protecting Stratospheric Ozone”
End of Chapter 20
PPT by Clark E. Adams