Presentation Slides for
Air Pollution and Global Warming:
History, Science, and Solutions
Chapter 11: Global Stratospheric Ozone Reduction
By Mark Z. Jacobson
Cambridge University Press (2012)
Last update: February 27, 2012
The photographs shown here either appear in the textbook or were obtained from the
internet and are provided to facilitate their display during course instruction.
Permissions for publication of photographs must be requested from individual
copyright holders. The source of each photograph is given below the figure and/or in
the back of the textbook.
Column Abundance of Ozone
Figure 11.1
Vertical Profiles of UV, O3, and O2
UV (photons/cm2/s x 10-14), O2 (molecules/cm3 x 10-18),
O3(g) (molecules/cm3 x 10-12)
Figure 11.7
Downward Solar Radiation at Top of
Atmosphere (TOA) and Ground
Figure 11.5
Major Absorbers of UV
Radiation at Different Altitudes
Wavelengths
(nm)
10-100
10-250
Dominant
Absorbers
N2
O2
Location of
Absorption
Thermosphere
Thermosphere-stratosphere
Near-UV
UV-C
UV-B
259-290
290-345
UV-A
320-380
O3
O3
Particles
NO2
Particles
Stratosphere
Stratosphere-troposphere
Polluted troposphere
Polluted troposphere
Polluted troposphere
Spectrum
Far-UV
Table 11.1
Skin Cancer v Annual UV Exposure
Skin Cancer
per 100,000
Population
Versus
Latitude
25N
Latitude
45N
www.ciesin.org
Variation with Latitude of Yearly- and
Zonally-Averaged Ozone
Figure 11.3
Variation with Latitude of October
Zonally-Averaged Ozone
Figure 11.10(b)
Variation with Latitude of March
Zonally-Averaged Ozone
Figure 11.11
Ozone Column Abundance in 2009
Versus Latitude and Day of Year
Latitude (degrees)
90
Ozone (DU) by latitude/day of year 2010 (Global: 291.5)
400
300
0
200
100
-90
0
90
180
270
360
Figure 11.2
Changes in Monthly-Averaged
Global Ozone From 1979-2011
Figure 11.8
Mount Pinatubo, June 12, 1991
Dave Harlow, United States Geological Survey
March- and October-Averaged
Ozone at High Latitudes Since 1979
Figure 11.10(a)
Ozone Column Abundance on
October 3, 2010
Latitude (degrees)
90
Ozone (DU) Oct. 3, 2010 (Global: 287.1; 60-90S: 223.6)
400
300
0
200
100
-90
-180
-90
0
90
180
Figure 11.16
Natural Ozone Production
O2(g) + h
Molecular
oxygen
O(1D)(g) + O(g)
 < 175 nm
Excited
Groundatomic state atomic
oxygen
oxygen
O2 (g) + h
M olecular
oxygen
O(g) + O(g)
Groundstate atomic
oxygen
 < 245 nm
M
O(1D)(g)
Excited
atomic
oxygen
O(g)
Groundstate atomic
oxygen
M
O(g) + O 2(g)
Ground- M olecular
state atomic oxygen
oxygen
O3(g)
Ozone
(11.1) - (11.4)
Natural Ozone Destruction
O3(g) + h
Ozone
O2(g) + O(1D)(g)
M olecular Excited
oxygen atomic
oxygen
 < 310 nm
O3(g) + h
Ozone
O2(g) + O(g)
M olecular Groundoxygen state atomic
oxygen
 > 310 nm
O(g) + O3(g)
Ground- Ozone
state atomic
oxygen
2O2(g)
M olecular
oxygen
(11.5) - (11.7)
Stratospheric NOx Production
N2O(g) + O(1D)(g)
Nitrous Excited
oxide
atomic
oxygen
NO(g) + NO(g)
Nitric oxide
(11.9)
NOx Ozone Catalytic Destruction
Cycle
NO(g) + O3(g)
Nitric
Ozone
oxide
NO2 (g) + O2(g)
Nitrogen Molecular
dioxide
oxygen
NO2(g) + O(g)
Nitrogen
Grounddioxide state atomic
oxygen
O(g) + O3(g)
Ground- Ozone
state atomic
oxygen
NO(g) + O2(g)
Nitric Molecular
oxide
oxygen
2O2(g)
M olecular
oxygen
(11.10) - (11.12)
Stratospheric HOx Production
1
O( D)(g) +
Excited
atomic
oxygen
H2O(g)
Water
vapor
OH(g)
Hydroxyl
radical
CH4(g)
M ethane
CH3(g)
M ethyl
radical
H2(g)
M olecular
hydrogen
OHg) +
Hydroxyl
radical
H
Atomic
hydrogen
(11.15)
HOx Ozone Catalytic Destruction
Cycle
OH(g) + O3(g)
Hydroxyl Ozone
radical
HO2(g) + O3(g)
Hydroperoxy Ozone
radical
2O3(g)
Ozone
HO2(g) + O2(g)
Hydroperoxy Molecular
radical
oxygen
OH(g) + 2O2(g)
Hydroxyl M olecular
radical
oxygen
3O2(g)
M olecular
oxygen
(11.16) - (11.18)
Removal of NOx and HOx From
Catalytic Cycles
NO2(g) + OH(g)
Nitrogen Hydroxyl
dioxide
radical
HO2(g) + NO2(g)
Hydroperoxy Nitrogen
radical
dioxide
HO2(g) + OH(g)
Hydroperoxy Hydroxyl
radical
radical
M
M
HNO3(g)
Nitric
acid
HO2NO2(g)
Peroxynitric
acid
H2O(g) + O2(g)
Water Molecular
vapor
oxygen
(11.13) - (11.19)
Chlorofluorocarbons Are Derived
From Carbon Tetrachloride (CCl4)
or Methane (CH4)
CH4 (Methane)
CFCl3 (CFC-11)
CF2Cl2 (CFC-12)
Chlorine Compounds
Chlorofluorocarbons
CFCl3 (CFC-11)
(1932)
CF2Cl2 (CFC-12)
(1928)
CFCl2CF2Cl (CFC-113) (1934)
Mixing ratio
(pptv)
Chemical
Lifetime (yr)
241
531
77
45
100
85
Hydrochlorofluorocarbons (HCFCs)
CF2ClH (HCFC-22)
(1943)
251
11.8
Other chlorinated compounds
CCl4 (Carbon tetrachloride)
CH3CCl3 (Methyl chloroform)
CH3Cl (Methyl chloride)
HCl (Hydrochloric acid)
88
7.3
580
10-1000
26
4.8
1.3
<1
Table 11.2
Bromine and Fluorine Compounds
Chemical
Bromocarbons-Halons
CF3Br (H-1301)
CF2ClBr (H-1211)
Mixing ratio Chemical
(pptv)
Lifetime (yr)
2.9
4.1
65
16
Other bromocarbons
CH3Br (Methyl bromide)
8
0.7
Fluorine compounds
CH2FCF3 (HFC-134a)
C2F6 (Perfluoroethane)
SF6 (Sulfur hexafluoride)
35
3.5
7.2
13.6
10,000
3200
Table 11.2
Variations With
Altitude of CFCs and
Other Chlorinated
Compounds
Chlorine Emission to Stratosphere
Chemical
Percent emission to stratosphere
Anthropogenic sources
CFC-12 (CF2Cl2)
CFC-11 (CFCl3)
Carbon tetrachloride (CCl4)
Methyl chloroform(CH3CCl3)
CFC-113 (CFCl2CF2Cl)
HCFC-22 (CF2ClH)
28
23
12
10
6
3
Natural sources
Methyl chloride (CH3Cl)
Hydrochloric acid (HCl)
15
3
Total
100
Table 11.3
Clx Ozone Catalytic Destruction
Cycle
Cl(g) + O 3(g)
ClO(g) + O 2(g)
Atomic Ozone
chlorine
Chlorine M olecular
monoxide oxygen
ClO(g) + O(g)
Chlorine
Groundmonoxide state atomic
oxygen
O(g) + O3(g)
Ground- Ozone
state atomic
oxygen
Cl(g) + O2(g)
Atomic M olecular
chlorine oxygen
2O2(g)
M olecular
oxygen
(11.23) - (11.25)
Removal of Clx From Catalytic
Cycles to Form Reservoirs
Cl(g) +
Atomic
chlorine
CH4(g)
Methane
CH3(g)
Methyl
radical
HO2(g)
Hydroperoxy
radical
O2(g)
Molecular
oxygen
H2(g)
Molecular
hydrogen
HCl(g) +
Hydrochloric
Hydrochloric
acie
acid
H2O2(g)
Hydrogen
peroxide
H(g)
Atomic
hydrogen
HO2(g)
Hydroperoxy
radical
M
ClO(g) + NO2(g)
Chlorine Nitrogen
monoxide dioxide
ClONO2(g)
Chlorine
nitrate
(11.26) - (11.27)
Brx Ozone Catalytic Destruction
Cycle
Br(g) + O 3(g)
Atomic Ozone
bromine
BrO(g) + O 2(g)
Bromine Molecular
monoxide oxygen
BrO(g) + O(g)
Bromine
Groundmonoxide state atomic
oxygen
O(g) + O3(g)
Ground- Ozone
state atomic
oxygen
Br(g) + O2(g)
Atomic M olecular
bromine oxygen
2O2(g)
M olecular
oxygen
(11.29) - (11.31)
Removal of Brx From Catalytic
Cycles to Form Reservoirs
Br(g) +
Atomic
bromine
O2(g)
Molecular
oxygen
HO2(g)
Hydroperoxy
radical
H2O2(g)
Hydrogen
peroxide
HBr(g) +
Hydrobromic
acid
HO2(g)
Hydroperoxy
radical
M
BrO(g) + NO2(g)
Bromine Nitrogen
monoxide dioxide
BrONO2(g)
Bromine
nitrate
(11.32) - (11.33)
Change in Size of Antarctic Ozone Hole
Figure 11.15
Smoking Gun
www.elmhurst.edu
Polar Stratospheric Clouds in
the Arctic (2000)
National Aeronautics and Space Administration
Summary of Ozone Hole Formation
Southern-Hemisphere winter (June-Sept.) without sunlight over
Antarctica --> cold
Polar vortex (jet stream) encircles Antarctica, confining air, cooling it
further
When temperatures drop below 195 K in the stratosphere, polar
stratospheric clouds (PSCs) form
On the surface of these clouds, “inactive” chlorine reservoirs, HCl(g)
and ClONO2(g), react to form Cl2(g), HOCl(g), ClNO2(g)
When sun rises in spring, sunlight breaks down new molecules into
“active” chlorine, which destroys ozone --> ozone hole
As air warm, PSCs melt, vortex breaks down, outside air brought in.
Ozone hole re-fills by November
Polar Stratospheric Clouds
Type I
Nitric acid trihydrate (NAT) HNO3-3H2O(s)
Form below 195 K
Comprise 90% of PSCs
Typical diameter: 1 mm
Typical number concentration: 1 particle cm-3
Type II
Water ice H2O(s)
Form below 187 K
Comprise 10% of PSCs
Typical diameter: 20 mm
Typical number concentration: <0.1 particle cm-3
Heterogeneous Reactions
ClONO2(g) + H 2O(s)
Chlorine
Water-ice
nitrate
ClONO2(g) + HCl(a)
Chlorine
Adsorbed
nitrate
hydrochloric
acid
N2O5(g) + H 2O(s)
Dinitrogen Water-ice
pentoxide
N2O5(g) + HCl(a)
Dinitrogen Adsorbed
pentoxide hydrochloric
acid
HOCl(g) + HCl(a)
Hypochlorous Adsorbed
acid
hydrochloric
acid
HOCl(g) + HNO3(a)
Hypochlorous Adsorbed
acid
nitric
acid
Cl2(g) + HNO3(a)
Molecular Adsorbed
chlorine
nitric
acid
2HNO3(a)
Adsorbed
nitric
acid
ClNO2(g) + HNO3(a)
Chlorine
Adsorbed
nitrite
nitric
acid
Cl2(g) + H 2O(s)
Molecular Water-ice
chlorine
(11.34) - (11.38)
Active Chlorine Formation in Spring
Cl2(g) + h
M olecular
chlorine
2Cl(g)
Atomic
chlorine
 < 450 nm
HOCl(g) + h
Hypochlorous
acid
Cl (g) + OH(g)
Atomic Hydroxyl
chlorine radical
 < 375 nm
ClNO2(g) + h
Chlorine
nitrite
Cl(g) + NO2(g)
Atomic Nitrogen
chlorine dioxide
 < 370 nm
(11.39) - (11.41)
Dimer Mechanism
2 x ( Cl(g) + O3(g)
Atomic Ozone
chlorine
ClO(g) + ClO(g)
Chlorine
monoxide
Cl2O2(g) + h
M
Cl2O2(g)
Dichlorine
dioxide
ClOO(g) + Cl(g)
Chlorine Atomic
peroxy chlorine
radical
Dichlorine
dioxide
ClOO(g)
Chlorine
peroxy
radical
ClO(g) + O 2(g) )
Chlorine Molecular
monoxide oxygen
M
2O3(g)
Ozone
< 360 nm
Cl(g) + O2(g)
Atomic Molecular
chlorine oxygen
3O2(g)
M olecular
oxygen
(11.42) - (11.46)
Bromine-Chlorine Mechanism
Cl(g) + O 3(g)
ClO(g) + O 2(g)
Atomic Ozone
chlorine
Chlorine M olecular
monoxide oxygen
Br(g) + O 3(g)
BrO(g) + O 2(g)
Atomic Ozone
bromine
Bromine M olecular
monoxide oxygen
BrO(g) + ClO(g)
Bromine
monoxide
Chlorine
monoxide
2O3(g)
Ozone
Br(g) + Cl(g) + O 2(g)
Atomic Atomic Molecular
bromine chlorine oxygen
3O2(g)
M olecular
oxygen
(11.47) - (11.50)
Conversion of Chlorine
Reservoirs to Active Chlorine
Figure 11.18
Ozone Regeneration
Change in globally-averaged ozone column abundance during two
global model simulations in which all ozone was initially removed
and chlorine was present and absent, respectively.
Figure 11.14
Regeneration of Ozone Vertical Profile
Time-evolution of modeled profile of ozone mixing ratio at 34oN
latitude, starting with zero ozone.
Altitude (km)
Altitude (km)
40
30
20
10
1h
6h
1d
5d
50 d
464 d
0
0
2
4
6
8
10
Ozone volume mixing ratio (ppmv)
Melanin
Dark pigment in skin for protection against UV radiation
Developed originally in populations living under intense UV
radiation in equatorial Africa
Populations that migrated to higher latitudes became lighter due to
natural selection since some UV is needed to produce vitamin D
in the skin, and dark pigmentation blocks the little UV available at
higher latitudes for vitamin D production. Vitamin D necessary to
prevent bone fractures, bow legs, slow growth (rickets).
As populations moved across Asia to North America and down
toward equatorial South America, production of melanin again
became an advantage
Lighter skin color in equatorial South America than in equatorial
Africa due to shorter presence of population in South America
Map of Migration 15,000 to >
100,000 years ago
Photoaging
TableDermnet
11.4
Basal Cell Carcinoma
Squamous Cell Carcinoma
Adam Healthcare
Squamous Cell Carcinoma
Sunsmart/healing daily
Cataract
Regulation of CFCs
June 1974: Effects of CFCs on ozone hypothesized by Rowland &
Molina
Dec. 1974: Bill to study, regulate CFCs killed in U.S. Congress
1975: Congress sets up committee to study CFC effects
1976: U.S. National Academy of Sciences releases report suggesting
long-term damage to ozone layer due to CFCs
1976: On basis of report, U.S Food and Drug Administration,
Environmental Protection Agency, Consumer Product Safety
Commission recommend phase out of spray cans in the U.S.
Oct. 1978: Manufacture/sale of CFCs for spray cans banned in U.S.
Regulation of CFCs
1980: U.S. EPA proposes limiting emission of CFCs from
refrigeration, but proposal rebuffed
1985: Vienna Convention.Initially 20 countries obligated to reduce
CFCs
1987: Montreal Protocol. Initially 27 countries agreed to limit CFCs
and Halons.
1990: London Amendments
1997+: Copenhagen and Subsequent Amendments
CFC Production Since the 1930s
Figure 11.20
CFC Sales
Trend
Figure 11.12
Phaseout Schedule of HCFCs
Year
2004
2010
2013
2015
2016
2020
2025
2030
2040
Percent
Reduction in
Consumption and
Production in
Developed Countries
30
75
90
99.5
100
Percent
Reduction in
Consumption
in Developing
Countries
0
10
35
67.5
97.5
100
Table 11.4
Ambient CFC-11, -12 Trends
Figure 11.21
Ambient CFC-113, HCFC-142b
Trends
Figure 11.21
Ambient HCFC-22, CCl4 Trends
Figure 11.21
Ambient H-1211, SF6 Trends
Figure 11.21