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SAP report on GWPs in Group I of Annex A, C and F
SAP co-chairs: David W. Fahey, Paul A. Newman,
John Pyle, Bonfils Safari SAP members
Background • Kigali Amendment comment, “204. …...the Scientific
Assessment Panel needs to begin the work .. to provide the Meeting of the Parties with the information it would require to adjust the global-warming potentials of the substances in Group I of Annex A, Annex C and Annex F …and .. it should report on its progress …to the Open-ended Working Group at its 39th meeting.”
• HCFC GWPs are necessary for calculating the Kigali amendment baselines for the HFC phase down
Outline
• What is a GWP? • Where do the Annex C and F GWP’s
come from? • How will these GWPs be updated?
Global Warming Potential • A GWP is a metric for evaluating the climate forcing of a
substance relative to CO2 over a specified period. • The global radiative forcing of 1-kg of a particular gas with
respect to 1-kg of CO2 over a time-period (e.g., 100 years). • GWP 100-yr, from Table 5A-1 in [WMO, 2014]
– CO2 = 1 – CH4 = 28 – N2O = 265 – CFC-11 = 4,660 – CFC-12 = 10,200
• Developed for the first IPCC assessment [Derwent, Rodhe, and Wuebbles, 1990] – Very similar to the ozone depletion potential (ODP), but for
comparing climate impacts
Group I Annex C The following table shall
replace the table for Group I in Annex C to the Protocol:
NotethemissingGWPvaluesformanysubstances.ThesearefromtheScien;ficAssessmentofOzoneDeple;on:2006[WMO,2007]
NotespecificallythoseHCFCsmissingGWPsinthe1989HCFCdataforA2Par;esand2009/2010HCFCdataforA5Par;es:
HCFC-121HCFC-122HCFC-133HCFC-141HCFC-142HCFC-225
BlankentryassumedZero
Current GWP Estimates from WMO [2014] Table 5A-1
How do we calculate the Global Warming Potential?
• The lifetime of the gas (τ) • Its radiative efficiency (Reff) • These rely on laboratory
measurements (kinetics, infrared spectra, etc) and/or empirical models.
We need to know:
GWPs have changed because the science and atmosphere are changing
2014 2010 2006 2002 1998 1994 1990 1400
1600
1800
2000
HC
FC-2
2 G
WP
100-
y
TheHCFC-22GWPchangesbecause:1) Thereferencelife@mechanges2) LabmeasurementsoftheIRabsorp@onareimproved3) TheabsoluteglobalwarmingofCO2changes(AGWP)
AnnexCcurrentvalue
WMOIPCC
A. HCFC-22 lifetime increaseB. Small change of IR spectrumC. Large decrease of CO2 AGWP
How do we calculate the Global Warming Potential?
IR absorption spectra, radiative efficiency C
ross
Sec
tion
(10-
18 c
m2 m
olec
ule-
1 )
010
200
1
2
Wavenumber (cm-1)500 1000 1500
Calculated spectraMeasured
Conformers: color codedPopulation weighted
HCFC-225ca (CHCl2CF2CF3)
Molecules like HCFC-225ca are important
climate gases because they absorb in the
atmospheric window
Papanastasiou,etal.[2017],NOAA
Global Warming Potentials have been estimated for HCFCs in Annex C
Life@mes GWPs
“Hydrochlorofluorocarbons(HCFCs)OzoneDeple;onandGlobalWarmingPoten;alDetermina;on”DimitriosK.Papanastasiou,P.Marshall,andJ.B.Burkholder[2017],NOAA
• Comprehensiveevalua;onofC1,C2,andC3HCFCs,for274compounds,includingallisomersandstableconformers
• Life;me,ODP,GWP,GTP• Thispaperwillbesubmi`edtoapeer-reviewedjournalthissummer.RE and Global Warming Potential (GWP) Results
C1
C2
C3
Increasing H
aa CHF2CCl2CF3
ba CHClFCClFCF3
bb CHF2CClFCClF2
ca CHCl2CF2CF3
cb CHClFCF2CClF2
cc CHF2CF2CCl2Fda CClF2CHClCF3
ea CClF2CHFCClF2
eb CCl2FCCHFCF3
RE range is a factor of 2 (0.15 – 0.3)
GWPs are isomer dependent• Reflects RE and Lifetime factors
Hodnebrog et al. (2013) RE method C1 C3
Increasing H
C2
Large range of GWP values (10 – 5500)
HCFC-225 Isomers
10
Life@mes GWPs
HCFC-235faCClF2CH2CF3HCFC-141b
C2H3Cl2F
Papanastasiou,etal.[2017],NOAA
The 2018 SAP Assessment will provide a listing of revised GWPs covering the Annex substances
• Scientific Assessment of Ozone Depletion: 2018 authors selected, and the 1st draft is being written. – The completed report will be available in Dec. 2018
• NOAA’s GWP revisions and new estimates will be discussed in Chapter 6: “Scenarios and information for policymakers” – Lead Authors: Lucy Carpenter and John Daniel – Co-authors: T. Hanaoka, J. Hu, K. Law, S. Tilmes, T. Wallington, H.
Walter-Terrinoni, D. Wuebbles, A. R. Ravishankara – Values to be tabulated in Assessment Appendix
• The uncertainty of GWP values is ~40%. Better accuracy could be achieved with dedicated laboratory experiments which are time consuming and expensive but could be carried out for key substances
Thank you for your attention