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CFCs and Stratospheric Ozone
F. Sherwood RowlandTokyo, Japan
October 5, 2007
International Ozone Conference, Oxford, U.K., 1936
Dobson Götz Chapman
Seasonal & Latitudinal Variations of Atmospheric Ozone (Dobson, 1968)
USSR
Australia
Switzerland
Peru
Lecture notes, F. S. Rowland,Fort Lauderdale, Florida , Feb. 1972
1973
Mario J. Molina & F. S. RowlandDepartment of Chemistry, University of California, Irvine, California 92664
Chlorofluoromethanes are being added to the environment in steadily increasing amounts. These compounds are chemically inert and may remain in the atmosphere for 40-150 years, and concentrations can be expected to reach 10 to 30 times present levels. Photodissociation of the chlorofluoromethanes in the stratosphere produces significant amounts of chlorine atoms, and leads to the destruction of atmospheric ozone.
Nature, June 28, 1974
The ozone problem
• O3 absorbs the sun’s UVC rays and most of the UVB rays
• Depletion of O3 means more UVB reaching the ground
• More UVB means more skin cancer
ATMOSPHERES
50
40
30
20
10
00 200 400 600 800
1.0
0.1
-.01
-.001
1972
LIFETIMESA 41 YEARSB 42 YEARSC 52 YEARS
TROPOPAUSE
ALTITUDE
KM
CHLORINE ATOMPRODUCTION RATE
CM-3 SEC-1
10 20
B,C
A
A B C
CCl3F PPTVCalculated vertical profile for CCl3F, 30°NRowland & Molina, Rev. Geophys. Space Phys., 1975
NOAA, 1975
NAS Reports
September 1976
September 13, 1976
TheTTT Ozone Hole: A hallenge for the scientific community
Observations made by Chubachi at theJapanese station Syowa and by Farmanand coworkers at the British Antarctic station of Halley Bay show a dramatic decrease in the ozone column during the 1970’s and 1970’s that is not simulatedby atmospheric models.
Halley Station
Chubachi
J. C. Farman, B. G. Gardiner, J. D. Shanklin
The Antarctic Ozone Hole
Observations made by Chubachi at the Japanese Antarctic station in Syowa and by Farman and co-workers at the British Antarctic station at Halley Bay showed a dramatic decrease of 50% or more in thespringtime (October) ozone column.
British Antarctic Survey Base, Halley Bay, Antarctica, 75.5° S
Farmanet al., 1985
White spaces = no data
HCl + ClONO2→ Cl2 + HNO3H. SATO & F. S. ROWLAND
05/15/84 17:43:09
05/15/84 17:43:10
05/15/84 17:43:11
05/15/84 17:43:12
HNO3 ClONO2
Add HCl
H2O + ClONO2 → HOCl + HNO3HCl + ClONO2 → Cl2 + HNO3
CONNELL AND WUEBBLES,1984
0
-10
-20
∆O3 %(a) STANDARD CASE(b) H2O(c) HCl
(a)(b)(c)
(a) 4.2%
(b) 24.0%
(c) 31.7% 1950 1960 1970 1980 0 100 200 400
DATE FUTURE YEARSFROM (1983)
Antarctic ClO (deZafra & P. Solomon 1987)
0.0 0.5 1.0 1.5 2.0
50
40
30
20
10
Alti
tude
(Km
)
O + O3 → 2O2 { Cl + O3 → ClO + O2ClO + O → Cl + O2
2[Cl + O3 → ClO + O2]2ClO →ClOOClClOOCl + hν → Cl + ClO2 → 2Cl + O2
2O3 → 3O2 {
Mixing Ratio (ppb)
Mid-winter, 28 July 1999 – 255 DU29 September 1999 – Total Ozone – 90 DU
-- Temperature
PSCs
PER
CEN
T D
IFFE
REN
CE
NORTH LATITUDE
% TOTAL OZONE CHANGEWINTER (DJFM)
(1976 – 1986) MINUS (1965 – 1975)
% OZONE CHANGES VERSUS LATITUDE(1970 – 1986) MINUS (1969 & EARLIER)
The 2006 Science Assessment• Worldwide effort involving >300 scientists as Cochairs, Lead
Authors, Coauthors, Contributors, and Reviewers
- MOST OF YOU ARE/WERE INVOLVED
• Now delivered to the Parties in response to their request (Terms of Reference, 15th MOP, Decision XV/53, November 2003)
• Fully reviewed three times by the international scientific community
• Is the 6th in the series of the SAP’s assessments for the Parties
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1989 1991 1994 1998 2002 2006
Global Ozone Observations
There are early signs that the ozone layer is starting its expected recovery.A clear statement on recovery would “require” having a clear decrease in ozone ANDAttribution of changes to all contributors…Coupling and non-linearity…
2010
?
Ozone Hole October 8, 2005
Total Ozone (Dobson Units)
110 220 330 440 550
Halley Bay 113 D.U.Punta Arenas 156 D.U.Ushuaia 161 D.U.
100
10.0
1.0
0.10
0.010
0.0010290 295 300 305 310
USHUAIA, ARGENTINA (55°S)AUSTRAL SPRING 1991
TOMS OZONE 189
TOMS OZONE 355
OCT. 20OCT. 21OCT. 23NOV. 6
UV WAVELENGTH, NANOMETERS
BIOSPHERIC INSTRUMENTS, INC.Surface UV-B intensities on 4 different days
Concentration of CCl3F (CFC-11) vs. time. Units parts per 1012 .Northern Hemisphere (blue), Global (green), Southern Hemisphere (red).
Dutton et al., NOAA/CMDL
280
270
260
1996 2000 2004C
FC-1
1 (p
pt)
Concentration of CCl2F2 (CFC-12) vs. time. Units parts per 1012 .Northern Hemisphere (blue), Global (green), Southern Hemisphere (red).
Dutton et al., NOAA/CMDL
530
520
510
500
1996 2000 2004C
FC-1
2 (p
pt)
Keeling and Whorf, 2005
Mauna Loa, Hawaii
(Red)
Wat
ts p
er s
quar
e m
eter
cool
ing
war
min
gIPCC
Dead Spruce, Kenai peninsula4,000,000 acres (16,000 sq.km.)killed by Spruce Bark Beetle;Failure to “winter kill” withhigher overnight temperatures NATIONALGEOGRAPHIC MAGAZINE SEPTEMBER 2004
16
Total Electricity Use, per capita, 1960 - 2001
0
2,000
4,000
6,000
8,000
10,000
12,000
14,00019
60
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
KW
h
12,000
8,0007,000
California
U.S.
kWh
Regulations and fiscal policies can make a difference