Download Ozone Depletion in the Stratosphere

Climate Change and Ozone Loss
G. Tyler Miller’s
Living in the Environment
13th Edition
Chapter 18
Key Concepts
• How does the Earth’s climate
fluctuate?
• What factors affect climate?
• What are the possible affects of
global warming?
• How are human activities
affecting the ozone layer?
Past Global Temperatures
Average surface temperature (°C)
Average temperature over past 900,000 years
17
16
15
14
13
12
11
10
9
900
800
700
600
500
400
300
Thousands of years ago
200
100
Present
Past Global Temperatures
Temperature change over past 22,000 years
2
Temperature change (°C)
Agriculture established
1
0
-1
-2
End of
last ice
age
-3
Average temperature over past
10,000 years = 15°C (59°F)
-4
-5
20,000
10,000
2,000
1,000
Years ago
200
100
Now
Recent Trends in Global
Temperature
Temperature change over past 1,000 years
Temperature change (°C)
1.0
0.5
0.0
-0.5
-1.0
1000 1100 1200 1300 1400 1500 1600 1700
Year
1800 1900 2000 2101
Recent Trends in Global
Temperature
Average surface temperature (°C)
Average temperature over past 130 years
15.0
14.8
14.6
14.4
14.2
14.0
13.8
13.6
1860
1880
1900
1920
1940
Year
1960
1980
2000
2020
Climate Change
 Past global
temperatures
 Recent trends
in global
temperatures
How do we know what past
temperature changes were?
• Radioisotopes in rocks and fossils
• Plankton and radioisotopes in ocean
sediments
• Pollen from lake bottoms
• Ice cores from ancient glaciers
• Tree rings
• Radioisotopes in corals
• Historical records
• Temperature measurements
The Natural Greenhouse Effect
(tropospheric heating effect)
Natural Cooling
Process
LOW
PRESSURE
Heat released
radiates to space
HIGH
PRESSURE
Cool, dry
air
Condensation
and
precipitation
Falls, is compressed, warms
Rises, expands, cools
Warm,
dry air
Hot, wet
air
Flows toward low pressure,
picks up moisture and heat
HIGH Moist surface warmed by sun LOW
PRESSURE
PRESSURE
Greenhouse Gases in the
Largest Concentration
• Water Vapor
• Carbon Dioxide
Hydrologic (Water) Cycle

The Carbon Cycle (Terrestrial)
The Carbon Cycle (Aquatic)
Greenhouse Gases from Human Activities
Greenhouse Gas
Average Time
in the
Troposphere
Relative
Warming
Potential (CO2)
Carbon Dioxide
Methane
Nitrous Oxide
Chloroflorocarbons
Hydrochloroflurocarbons
Hydroflurocarbons
50-120 years
12-18 years
114-120 years
11-20 years
9-390 years
15-390 years
130-12,700
Halons
Carbon
Tetrachloride
65 years
42 years
5,500
1,400
1
23
296
900-8,300
470-2,000
Climate Change and Human Activities
1) Increased use of fossil fuels (CO2 , CH4)
2) Deforestation (CO2 , N2O)
3) Cultivation of Rice Patties (N2O)
Global warming = Enhanced greenhouse effect
– Melting icecaps and glaciers
– Coral reef bleaching
– Other
Connections
14.7
380
8.0
14.6
7.6
7.2
6.8
6.4
6.0
CO2 concentration (ppm)
375
14.5
Fossil fuels
14.4
365
Temperature
14.3
355
14.2
345
14.1
5.6
CO2
14.0
335
5.2
4.8
13.9
325
1970
13.8
1980
1990
Year
2000
2005
Temperature (Cº)
Fossil fuels burn
(billions of metric tons of oil equivalent)
8.4
Projecting Future Changes in
Earth’s Climate
 Climate models
(see Spotlight p. 457)
 Apparent
influence of
human activities
 Could be
natural changes
Fig. 18-11 p. 455
Factors Affecting Changes in
Earth’s Average Temperature
 Changes in solar output
 Changes in Earth’s albedo
 Moderating effect of
oceans
 Clouds and water
vapor
 Air pollution
Some Possible Effects of a
Warmer World
•
•
•
•
•
•
Water Distribution
Plant and Animal Biodiversity Loss
Ocean Currents and Sea Levels
Extreme Weather
Human Population and Health
Agriculture and Forests
Some Possible Effects of a
Warmer World
Fig. 18-16
p. 461
Solutions: Dealing with the Threat
of Climate Change
Fig. 18-20 p. 466
Options
 Do nothing
 Do more research
 Act now to reduce risks
 Act now no-regrets
strategy
Removing CO2 From the Atmosphere
Tree
plantation
Coal
power plant
Tanker delivers
CO2 from plant
to rig
Abandoned
oil field
CO2 is pumped
down to reservoir
through abandoned oil field
Oil rig
CO2 is
pumped down
from rig for
Deep ocean
disposal
Crop field Switchgrass
field
Spent oil reservoir is
used for CO2 deposit
= CO2 deposit
= CO2 pumping
Fig. 18-21
p. 467
Reducing Greenhouse Gas Emissions
• Rio Earth Summit (1992)
– 106 nations
– Scientific uncertainty must not be
used as justification to do nothing.
– Industrialized nations must take lead
in slowing down rate and degree of
global warming.
– Developed countries voluntarily
committed to reducing CO2 to 1990
levels by the year 2000
Reducing Greenhouse Gas Emissions
• Kyoto Treaty (1997)
– 161 nations
– Required 38 developed countries to cut
greenhouse emissions 5.2% below 1990
levels by 2012..
– Did not require developing countries to
make cuts.
– Allowed emission trading among
participating countries.
– Was not ratified until 2005
– Approximately 180 participating countries.
United States did not ratify
Kyoto Treaty 1) Treaty fails to require emission
reductions from developing
countries (81% of world’s
population)
2) Economists predicted it would
have devastating impact on U.S.
economy and workers
Some U.S. CO2 Reductions
• Concern among leaders of some U.S. companies.
• Several major companies have established targets
to reduce greenhouse gas emissions by 10-65%
from 1990 levels by 2010.
• Automobile companies investing in hybrid gaselectric and fuel cell engines.
• Local governments established programs to reduce
greenhouse gas emissions.
• California first state to require a reduction in CO2
emissions from motor vehicles beginning in 2009.
A growing number of analysts
suggest we should begin to
prepare for the possible
effects of long-term
atmospheric warming and
climate change!
Ozone Depletion in the
Stratosphere
(the other story)
40
25
35
Altitude (kilometers)
30
25
Stratospheric ozone
20
15
Altitude (miles)
Stratosphere
Benefical Ozone
20
10
15
10
Troposphere
5
Photochemical ozone
0
0
5
Harmful Ozone
5
10
15
Ozone concentration (ppm)
0
20
Ozone Depletion in the Stratosphere
Importance of Ozone
• Essential for terrestrial life
• Reduces sunburn
• Prevents tropospheric ozone
Ozone Depletion in the Stratosphere
Fig. 18-26 p. 473
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and leaving CFCl2.
Once free, the chlorine
atom is off to attack
another ozone molecule
and begin the cycle again.
Sun
Cl
Cl
C
Cl
F
UV radiation
Cl
Cl
O
O
The chlorine atom attacks an
ozone (O3) molecule, pulling
an oxygen atom off it and
O
O O
leaving an oxygen
molecule (O2).
Cl
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
Cl
molecule to form O2.
O
O
The chlorine atom and
the oxygen atom join to
form a chlorine monoxide
molecule (ClO).
Cl
O
O
Stepped Art
O
Fig. 20-18, p. 486
Ozone Depleting Chemicals
Chlorofluorocarbons (CFCs)
Methyl bromide (fumigant)
Halons (fire extinguishers)
Carbon tetrachloride (solvent)
Methyl chloroform (cleaning
solvent and propellant)
N-propyl bromide (solvent)
OZONE DEPLETION IN THE
STRATOSPHERE
• During four
months of each
year up to half of
the ozone in the
stratosphere over
Antarctica and a
smaller amount
over the Artic is
depleted.
Seasonal Thinning at the Poles
Ozone thinning
(hole)
Polar
vortex
Fig. 18-30 p. 475
Reasons for Concern
 Increased incidence and severity of sunburn
 Increase in eye cataracts
 Increased incidence of skin cancer
 Immune system suppression
 Increase in acid deposition
 Lower crop yields and decline in productivity
This long-wavelength
This shorter-wavelength (high-energy) form
(low-energy) form of UV
of UV radiation causes sunburn, premature
radiation causes aging of Ultraviolet
Ultraviolet aging, and wrinkling. It is largely responsible
A
the skin, tanning, and
for basal and squamous cell carcinomas
B
sometimes sunburn. It
and plays a role in malignant melanoma.
penetrates deeply and
may contribute to skin
cancer.
Thin layer of
dead cells
Squamous
cells
Basal layer
Hair
Epidermis
Sweat
gland
Melanocyte
cells
Dermis
Basal cell
Blood
vessels
Squamous Cell
Carcinoma
Basal Cell
Carcinoma
Melanoma
Fig. 20-22, p. 489
Solutions: Protecting the Ozone Layer
 Use CFC substitutes
 Montreal Protocol (1987)
only CFCs
 Copenhagen
Protocol (1992)
all ODCs
Characteristics of Global Warming
and Ozone Depletion
Global Warming
Ozone Depletion
CO2, CH4, NOx
(greenhouse gases)
O3, O2, and CFCs
Absorbs infrared (IR)
radiation
Absorbs ultraviolet (UV)
radiation
Raising the earth’s
surface temperature
Decreasing O3
concentration in the
stratosphere
Decrease burning of
fossil fuels
Eliminate CFCs
2007 FRQ #3