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Transcript
Climate Change and Ozone Loss
Key Concepts
 Changes in Earth’s climate over time
 Factors affecting climate
 Possible effects of global warming
 Adapting to climate change
 Human impacts on the ozone layer
 Protecting and restoring the ozone layer
Past Climate Changes
 Past global
temperatures
 Recent trends in
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
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
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
The Greenhouse Effect
 Greenhouse effect
 Greenhouse gases
Table 21-1 Major Greenhouse Gases from Human Activities
Average Time in
the Troposphere
Relative Warming
Potential
(compared to CO2)
Greenhouse Gas
Human Sources
Carbon dioxide (CO2)
Fossil fuel burning, especially coal (70–
75%), deforestation, and plant burning
100–120 years
1
Methane (CH4)
Rice paddies, guts of cattle and termites,
landfills, coal production, coal seams, and
natural gas leaks from oil and gas
production and pipelines
12–18 years
23
Nitrous oxide (N2O)
Fossil fuel burning, fertilizers, livestock
wastes, and nylon production
114–120 years
296
Chlorofluorocarbons
(CFCs)*
Air conditioners, refrigerators, plastic foams
11–20 years (65–110
years in stratosphere)
900–8,300
HydrochloroAir conditioners, refrigerators, plastic foams
fluorocarbons (HCFCs)
9–390
470–2,000
Hydrofluorocarbons
(HFCs)
Air conditioners, refrigerators, plastic foams
15–390
130–12,700
Halons
Fire extinguishers
65
5,500
Carbon tetrachloride
Cleaning solvent
42
1,400
360
340
320
300
280
Carbon dioxide
260
240
220
+2.5
200
0
180
–2.5
–5.0
Temperature
change
End of
last ice age
160
120
80
40
0
Thousands of years before present
–7.5
–10.0
Variation of temperature (˚C)
from current level
Concentration of carbon dioxide
in the atmosphere (ppm)
380
Parts per million
410
360
310
260
1800
1900
2000
Year
Carbon dioxide (CO2)
2100
Parts per million
2.4
1.8
1.2
0.6
1800
1900
2000
Year
Methane (CH4)
2100
320
Parts per million
310
300
290
260
1800
1900
2000
Year
Nitrous oxide (N2O)
2100
Climate Change and Human Activities
Increased use of fossil fuels
Deforestation
Global warming
Melting icecaps and glaciers
Rising sea level
Table 21-2 Major Characteristics of Global Warming and Ozone Depletion
Characteristic
Global Warming
Ozone Depletion
Region of
atmosphere involved
Troposphere.
Stratosphere.
Major
substances involved
CO2, CH4, N2O (greenhouse gases).
O3, O2, chlorofluorocarbons (CFCs).
Interaction with radiation Molecules of greenhouse gases absorb infrared
(IR) radiation from the earth’s surface, vibrate,
and release longer-wavelength IR radiation (heat)
into the lower troposphere. This natural
greenhouse effect helps warm the lower
troposphere.
About 95% of incoming ultraviolet (UV)
radiation from the sun is absorbed by O3
molecules in the stratosphere and does
not reach the earth’s surface.
Nature of problem
There is a high (90–99%) probability that
increasing concentrations of greenhouse gases in
the troposphere from burning fossil
fuels,deforestation, and agriculture are enhancing
the natural greenhouse effect and raising the
earth’s average surface temperature (Figure 21-2,
bottom right, and Figure 21-11, p. 471).
CFCs and other ozone-depleting
chemicals released into the troposphere
by human activities have made their way
to the stratosphere, where they decrease
O3 concentration. This can allow more
harmful UV radiation to reach the earth’s
surface.
Possible consequences
Changes in climate, agricultural productivity,
water supplies, and sea level.
Increased incidence of skin cancer, eye
cataracts, and immune system
suppression and damage to crops and
phytoplankton.
Possible responses
Decrease fossil fuel use and deforestation;
prepare for climate change.
Eliminate or find acceptable substitutes
for CFCs and other ozone-depleting
chemicals.
Greenland
Clouds 50–55%
Snow 80–90%
City 10–15%
Forest 5%
Grass 15–25%
Bare sand 30–60%
Oceans 5%
Height above or below
present sea level (meters)
0
250,000
0
–130
–426
200,000
150,000
100,000
Years before present
50,000
0
Present
Height above or below
present sea level (feet)
Today’s sea level
Projecting Future Changes in Earth’s
Climate
Climate models
Apparent influence of human activities
Could be natural changes
Troposphere
Warming
from
decrease
Aerosols
Cooling
from
increase
CO2 removal
by plants
and soil
organisms
CO2 emissions
from land
cleaning, fires,
and decay
Heat and
CO2 removal
Heat and
CO2 emissions
Greenhouse
gases
Ice and snow cover
Shallow ocean
Land and soil biota
Natural and human emissions
Long-term
storage
Deep ocean
Cell
Clouds
Land
Ocean
6.0
5.5
5.0
Change in temperature (ºC)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 2100
Year
Factors Affecting the Earth’s
Temperature
Changes in solar output
Changes in Earth’s albedo
Moderating effect of oceans
Clouds and water vapor
Air pollution
Greenland
Antarctica
Some Possible Effects of a
Warmer World
Possible Benefits from a Warmer
Atmosphere
Less severe winters
More precipitation in some dry areas
Less precipitation in some wet areas
Increased food production in some areas
Expanded population and ranges of some
species
Present
range
Future
range
Overlap
100
Mean Sea-Level Rises (centimeters)
90
80
70
High Projection
Shanghai, New Orleans,
and other low-lying cities
largely underwater
60
50
40
30
Medium Projection
More than a third of U.S.
wetlands underwater
20
10
Low Projection
0
2010
2020
2030
2040
2050
Year
2060
2070
2080
2090
2100
Oil rig
Coal
power plant
Tanker delivers
CO2 from plant
to rig
Tree
plantation
CO2 is
pumped down
from rig for deep
ocean disposal
Abandoned
oil field
Switchgrass
Crop field
CO2 is pumped
down to reservoir
through abandoned oil field
Spent oil reservoir is
used for CO2 deposit
= CO2 deposit
= CO2 pumping
What Can You Do?
Reducing CO2 Emissions
• Drive a fuel-efficient car, walk, bike, carpool,
and use mass transit
• Use energy-efficient windows
• Use energy-efficient appliances and lights
• Heavily insulate your house and seal all drafts
• Reduce garbage by recycling and reuse
• Insulate hot water heater
• Use compact fluorescent bulbs
• Plant trees to shade your house during summer
• Set water heater no higher than 49°C (120°F)
• Wash laundry in warm or cold water
• Use low-flow shower head
Solutions: Dealing with the Threat
of Climate Change
Options
 Do nothing
 Do more research
 Act now to reduce
risks
 Precautionary
principle
Solutions
Global Warming
Prevention
Cut fossil fuel use (especially coal)
Shift from coal to natural gas
Improve energy efficiency
Shift to renewable energy resources
Transfer energy efficiency and
renewable energy technologies
to developing countries
Cleanup
Remove CO2 from smokestack
and vehicle emissions
Store (sequester) CO2 by
planting trees
Sequester CO2 deep underground
Sequester CO2 in soil by using
no-till cultivation and taking crop
land out of production
Reduce deforestation
Use more sustainable agriculture
Limit urban sprawl
Reduce poverty
Slow population growth
Sequester CO2 in the deep ocean
Repair leaky natural gas
pipelines and facilities
Use feeds that reduce
CH4 emissions by
belching cows
Reducing Greenhouse Gas Emissions
 Kyoto Treaty (1997)
 U.S. withdraws from Kyoto Treaty (2001)
 Other reductions in CO2
Loss of the Ozone Layer: 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
When did it all begin?
• Dramatic loss of ozone in the lower
stratosphere over Antarctica was first noticed
in the 1970s by a research group.
• They were monitoring the atmosphere above
Antarctica from a research station
Research Station in Antarctica
The Atmosphere
•
Where and how ozone is formed?
• Ozone (O3) forms a layer in the stratosphere,
thinnest in the tropics (around the equator) and
denser towards the poles.
• It is created when ultraviolet radiation
(sunlight) strikes the stratosphere, dissociating
(or "splitting") oxygen molecules (O2) to
atomic oxygen (O).
• The atomic oxygen quickly combines with
further oxygen molecules to form ozone (O3 )
Where is the Ozone “hole” ?
• Over Antarctica (and recently over the Arctic),
stratospheric ozone has been depleted at
certain times of the year.
• This is mainly due to the release of man-made
chemicals containing chlorine such as CFC's
(Chlorofluorocarbons), but also compounds
containing bromine, other related halogen
compounds and also nitrogen oxides (NOx).
Ozone Depleting Chemicals
 Chlorofluorocarbons (CFCs)
 Halons
 Methyl bromide
 Carbon tetrachloride
 Methyl chloroform
 Hydrogen chloride
Former Uses of CFCs
Air Conditioners
Refrigerators
Spray cans
Cleaners for electronic parts
Sterilizing medical instruments
Fumigants for granaries and cargo ships
CFC’s in the air
Ozone Depletion in the Stratosphere
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and leaving
CFCl2.
Sun
Cl
Cl
C
F
Cl
UV radiation
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
Cl
Cl
O
O
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom
off it and leaving
O
O
O
an oxygen
molecule (O2).
Cl
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Repeated
Cl + O Cl + O2
many times
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
Cl
molecule to form O2.
O
O
Cl
The chlorine
atom and the
O
oxygen atom join
O
to form a chlorine
monoxide molecule O
(ClO).
Seasonal Ozone Layer Thinning at
the Poles
Ozone thinning (hole)
Polar vortex
January 1995
October 1995
It’s getting bigger……..
• Satellite measurements in September 2000
revealed that the stratospheric ozone “hole”
over the Antarctic had a reached a record 28.3
million square kilometers (some one million
sq. km more than the previous record, in
1998).
October 1980- October 2002
Total ozone (Dobson units)
400
October monthly means
350
300
250
200
150
100
1955
1960
1965
1970
1975
1980
Year
1985
1990
1995
2000
2005
35
August 6, 2003
30
October 11, 2003
Altitude (kilometers)
25
20
15
10
5
0
5
10
15
Ozone partial pressure (milipascals)
Natural Capital Degradation
Effects of Ozone Depletion
Human Health
• Worse sunburn
• More eye cataracts
• More skin cancers
• Immune system suppression
Food and Forests
• Reduced yields for some crops
• Reduced seafood supplies from reduced phytoplankton
• Decreased forest productivity for UV-sensitive tree species
Wildlife
• Increased eye cataracts in some species
• Decreased population of aquatic species sensitive to UV radiation
• Reduced population of surface phytoplankton
• Disrupted aquatic food webs from reduced phytoplankton
Air Pollution and Materials
• Increased acid deposition
• Increased photochemical smog
• Degradation of outdoor paints and plastics
Global Warming
• Accelerated warming because of decreased ocean uptake of CO2
from atmosphere by phytoplankton and CFCs acting as greenhouse
gases
What are some of the dangers
associated with the ozone hole?
• Experts predict that an estimated 10 %
reduction in the ozone layer will result in a
25% increase in non-melanoma skin cancer
rates for temperate latitudes by the year 2050.
Skin Cancers
Melanoma
Squamous Cell Carcinoma
Basal Cell Carcinoma
Ultraviolet A
Ultraviolet B
Thin layer of
dead cells
Hair
Epidermis
Squamous
cells
Basal
layer
Sweat
gland
Melanocyte
cells
Dermis
Basal
cell
Blood
vessels
Squamous Cell Carcinoma
Basal Cell Carcinoma
Melanoma
What Can You Do?
Reducing Exposure to UV-Radiation
• Stay out of the sun, especially between 10 A.M. and 3
P.M.
• Do not use tanning parlors or sunlamps.
• When in the sun, wear protective clothing and sun–
glasses that protect against UV-A and UV-B radiation.
• Be aware that overcast skies do not protect you.
• Do not expose yourself to the sun if you are taking
antibiotics or birth control pills.
• Use a sunscreen with a protection factor of 15 or 25 if
you have light skin.
• Examine your skin and scalp at least once a month
for moles or warts that change in size, shape, or color
or sores that keep oozing, bleeding, and crusting
over. If you observe any of these signs, consult a
doctor immediately.
Skin Cancer Fact Sheet
• Over half of all new
cancers are skin
cancers.
An estimated 10,250
people will die of skin
cancer this year.
• More than 1 million
new cases of skin
cancer will be
diagnosed in the United
States this year.
One person dies of
melanoma every hour.
More Facts
• At current rates one in
37 Americans have a
lifetime risk of
developing melanoma
and one in 65
Americans have a
lifetime risk of
developing invasive
melanoma.
• The incidence of
melanoma more than
tripled among
Caucasians between
1980 and 2003.
• More than 77 percent of
skin cancer deaths are
from melanoma.
Solutions: Protecting the Ozone Layer
 CFC substitutes
 Montreal Protocol
 Copenhagen Protocol
Abundance (parts per trillion)
15,000
No protocol
12,000
1987
Montreal
Protocol
9,000
6,000
1992
Copenhagen
Protocol
3,000
0
1950
1975
2000
2025
Year
2050
2075
2100