THEOZONEHOLE...
MONTREALPROTOCOL
GEOG/ENST3331–Lecture17
Ahrens:Chapter18;Turco:Chapter13
TheOzoneHole
¨ 
Polarstratosphericclouds
¤  Polarvortex
¤  Cloudformation
Chlorineatthepoles
¨  Remediation
¨ 
Polarstratosphere
¨ 
Noinsolationduringthewinter
¤  Largetemperaturegradientdevelops
¤  Largepressuregradientresults
¨ 
Lowpressureoverpolesinstratosphere
¤  Geostrophicwindscirclethepole
¤  IntensiGiesallwinter
Polarvortex
Barriertomixing
¨  Antarcticvortexis
particularlystrong
¨ 
¤  -93°C
¤  Windsupto300km/hr
¤  Arcticvortexis
somewhatweaker
becauseofalternating
landandoceanbelow
Turco:Figure13.24
Polarvortex
¨ 
Poleisisolateduntilspring
¤ 
¨ 
¨ 
Nowarmaircanmixin
Winter
Windsreversesdirectionin
summer(muchweaker)
Duringthereversal,rapid
mixingcanoccur
Spring
Polarstratosphericclouds(PSC)
¨ 
Composedof:
¤  Type1:Frozennitric
acid(HNO3)
¤  Type2:Ice
¨ 
Causedbyextreme
cooling:
¤  <-73°C(Type1)
¤  <-78°C(Type2)
Nacreouscloud
Chlorineinthestratosphere
Cl+O3→ClO+O2
ClO+O→Cl+O2
___________________
Net: O+O3→2O2
¨  Buteventually:
Cl+CH4→HCl+CH3
ClO+NO2→ClONO2(chlorinenitrate)
¨ 
99%ofchlorineinthestratosphereisHClorClONO2
Polarstratosphericclouds
1. 
SuckHNO3outofair
¤  DrawsdownNO2concentration
¤  LesschlorinenitrateproductiontoremoveCl
2. 
Providesolidsurfacesforchemicalreactions:
HCl+ClONO2→Cl2+HNO3
¨ 
Whensunlightreturns:
Cl2+UV→Cl+Cl
¤  ConcentrationofreactiveClincreases100timesin
thepolarspring
TheOzoneHole
Antarcticwinter:highlevelsofCl2
¨  Antarcticspring:
¨ 
¤  Cl2splitintoCl
¤  O3concentrationdrops90%inafewweeks
¨ 
Eventually:
¤  Polarvortexbreaksdown
¤  O3andNO2replenishedfromlowerlatitudes
Lectureoutline
Polarstratosphericclouds
¨  Chlorineatthepoles
¨  Remediation
¨ 
¤  TheMontréalProtocol
GlobalozonedepleEon
Turco:Figure13.29
InternaEonalnegoEaEon
¨ 
¨ 
1985ViennaConventionfortheProtectionofthe
OzoneLayer
1987MontréalProtocolonSubstancesthat
DepletetheOzoneLayer
¤  ReduceCFCemissionsby50%by2000
¤  Furthercutstobenegotiated
1987MontréalProtocol
¨ 
Agreedon16September1987;enteredintoforce
on1January1989
¤  ReduceCFCemissionsby50%by2000
¤  Furthercutstobenegotiated
¨ 
Eightrevisionstodate
¤  Asaresultoftheinternationalagreement,theozone
holeinAntarcticaisslowlyrecovering.
¤  Climateprojectionsindicatethattheozonelayerwill
returnto1980levelsbetween2050and2070
SubsEtuEonforCFCs
¨ 
Someeasy
¤  Aerosolpropellants
¤  Fireextinguishing
¤  Solvents(e.g.drycleaning)
¨ 
SomemoredifGicult
¤  Coolants
n  HCFCs,HFCs
MontrealProtocolMulElateralFund
Toassistdevelopingcountrypartiestothe
MontrealProtocoltocomplywiththecontrol
measuresoftheProtocol.
¨  whoseannualpercapitaconsumptionand
productionofozonedepletingsubstances(ODS)is
lessthan0.3kg
¨ 
1987MontréalProtocol
TwoozonetreatieshavebeenratiGiedby197
parties,whichmakingthemtheGirstuniversally
ratiGiedtreatiesinUnitedNationshistory
¨  BetweenthebasicscientiGicresearchdiscoveryin
1973andtheinternationalagreementsigned
1987only14yearslapsed.
¨ 
Thepathtaken
¨ 
¨ 
1985ViennaConventionfortheProtectionofthe
OzoneLayer
1987MontréalProtocolonSubstancesthat
DepletetheOzoneLayer
¤  ReduceCFCemissionsby50%by2000
¤  Furthercutstobenegotiated
InternaEonalnegoEaEon
However,thehydrochloroGluorocarbons(HCFCs)and
hydroGluorocarbons(HFCs)contributeto
anthropogenicglobalwarming.Onamolecule-for-molecule
basis,thesecompoundsareupto10,000timesmore
potentasgreenhousegasesthancarbondioxide.The
MontrealProtocolcurrentlycallsforacompletephase-out
ofHCFCsby2030,butdoesnotplaceanyrestrictionon
HFCs.SincetheCFCsthemselvesareequallypowerful
greenhousegases,themeresubstitutionofHFCsforCFCs
doesnotsigniGicantlyincreasetherateofanthropogenic
globalwarming,butovertimeasteadyincreaseintheir
usecouldincreasethedangerthathumanactivitywill
changetheclimate.
TreatyonozonedepleEngsubstances
¨ 
Club-within-a-club:
¤  1987:MontréalProtocolhas24parties
n  1989:smallgroupofcountriesmovefrom50%
reductionto100%
¤  1990:LondonAmendments
n  93countriesagreetonewtargets
MontréalProtocol
¨ 
Continuedratcheting:
¤  1992:CopenhagenAmendments
n  Speduptargets,especiallybrominecompounds
(halons)
n  CaponHCFCs
¤  2007adjustment:
n  200countriesagreedtoeliminateHCFCsby2020
MontréalProtocol
¨ 
Differentialobligations
¤  Article5countries(LDCs)havedelayedtargets
¤  Eg.2030forHCFCs
¨ 
Multilateralfund:
¤  Directandindirectfunding
¤  Over1991-2005,US$2.1billion
Outcomes
Verysuccessfultreaty
¤  Highcompliance
¤  CFCproductionhasalmostceased
¤  CFCconcentrationshavedecreased
¤  Ozonelayershowssomesignsofrecovery
AcEon
Sources–easilyidentiGiable–DuPont
¨  Replacementsreadilyavailable
¨ 
¤  CO2aspropellantinaerosols
¤  HFCs,HCFCsusedascoolants
¤  Lemonjuiceassolventforcleaningelectronics
¨ 
Economicallyinexpensive
TheRoadnotTaken
¨ 
“TheRoadNotTaken”,featuredinMountain
Interval(1916)acollectionofpoemsbyRobert
Frost,seemstobeafairlysimplehomilyabout
makingchoices:
“Tworoadsdivergedinayellowwood,
…
Itooktheonelesstraveledby,
Andthathasmadeallthedifference.”
ARoadavoided
Health benefits
¨ 
Asoftheendof2009,
thePartiestothe
Protocolhadphased
outtheconsumptionof
98%ofallofthe
chemicalscontrolledby
theProtocol
Itisestimatedthatthe
globalcommunityavoids
millions of cases of fatal
skin cancer and tens of
millions of cases of non
fatal skin cancer and
cataracts.
ARoadavoided(cont.)
Health benefits
Health benefits
In the United States the
EPA estimates that by the
year 2165 more than 6.3
million skin cancer deaths
will have been avoided and
saved it an estimated $4.2
trillion in health care costs
during 1990–2165.
more than 22 million
additional cataract cases
will be avoided for
Americans born
between 1985 – 2100 due
to Montreal Protocol
Whatwouldhavehappenedtotheozone
layerifCFCshadnotbeenregulated?
“We simulated a world avoided, and it’s a world we
should be glad we avoided.”
“The Montreal Protocol is a remarkable international
agreement that should be studied by those involved
with global warming and the attempts to reach
international agreement on that topic.”
Source: Newman, Stolarski et al. (2009). What would have
happened to the ozone layer if chlorofluorocarbons (CFCs) had not been
regulated? Atmospheric Chemistry and Physics, 9(6), 2113-2128.
Remainingcausesforconcern
¨ 
CFCswillstillbepresentforalongtime
¨ 
Veryhighaltitudeaircraftwouldexacerbatetheproblem
¨ 
StratosphereiscoolingasaresultofincreasingCO2
¤ 
¤ 
CouldleadtoArcticozonehole
Couldalsoleadtodecreasedozonelevelsoverheavilypopulated
areas
2011:ArcEcOzoneHole
ArcEcOzoneHole
¨ 
Ozonelevelsdroppedby80%
¤  ComparabletoAntarctichole
¤  Twiceasmuchaseverrecordedpreviously
¨ 
2millionkm2
¤  TwicetheareaofOntario
¨ 
Productofunusuallycoldstratosphere
Otherconcerns
CFCsarepotentgreenhousegases
¨  HCFCsandHFCsarealsopotentgreenhouse
gases
¨ 
¤  Alsohavelongatmosphericresidencetimes
¨ 
Alternativesthatarefriendlytoboththeozone
layerandclimatehaveyettobedeveloped
Instrumental temperature record
1950-2015
Zero line is 1951-1980 average global temperature
Comingup!
Global
ClimateChange
1800:13.6°C
1880:13.7°C
1920:13.7°C
1965:14.0°C