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