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

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1 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

2 Background Kigali Amendment comment, 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 39 th meeting. HCFC GWPs are necessary for calculating the Kigali amendment baselines for the HFC phase down

3 Outline What is a GWP? Where do the Annex C and F GWP s come from? How will these GWPs be updated?

4 Global Warming Potential A GWP is a metric for evaluating the climate forcing of a substance relative to CO 2 over a specified period. The global radiative forcing of 1-kg of a particular gas with respect to 1-kg of CO 2 over a time-period (e.g., 100 years). GWP 100-yr, from Table 5A-1 in [WMO, 2014] CO 2 = 1 CH 4 = 28 N 2 O = 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

5 Group I Annex C The following table shall replace the table for Group I in Annex C to the Protocol: Note specifically those HCFCs missing GWPs in the 1989 HCFC data for A2 Par;es and 2009/2010 HCFC data for A5 Par;es: HCFC-121 HCFC-122 HCFC-133 HCFC-141 HCFC-142 HCFC-225 Note the missing GWP values for many substances. These are from the Scien;fic Assessment of Ozone Deple;on: 2006 [WMO, 2007] Blank entry assumed Zero

6 Current GWP Estimates from WMO [2014] Table 5A-1

7 How do we calculate the Global Warming Potential? We need to know: The lifetime of the gas (τ) Its radiative efficiency (R eff ) These rely on laboratory measurements (kinetics, infrared spectra, etc) and/ or empirical models.

8 GWPs have changed because the science and atmosphere are changing 2000 HCFC-22 GWP 100-y A. HCFC-22 lifetime increase B. Small change of IR spectrum 1400 C. Large decrease of 1990 CO 2 AGWP Annex C current value WMO IPCC The HCFC-22 GWP changes because: 1) The reference life@me changes 2) Lab measurements of the IR absorp@on are improved 3) The absolute global warming of CO 2 changes (AGWP)

9 How do we calculate the Global Warming Potential? IR absorption spectra, radiative efficiency Cross Section (10-18 cm 2 molecule -1 ) Papanastasiou, et al. [2017], NOAA HCFC-225ca (CHCl 2 CF 2 CF 3 ) Calculated spectra Measured Conformers: color coded Population weighted Wavenumber (cm -1 ) Molecules like HCFC-225ca are important climate gases because they absorb in the atmospheric window

10 Global Warming Potentials have been estimated for HCFCs in Annex C Hydrochlorofluorocarbons (HCFCs) Ozone Deple;on and Global Warming Poten;al Determina;on Dimitrios K. Papanastasiou, P. Marshall, and J. B. Burkholder [2017], NOAA Comprehensive evalua;on of C1, C2, and C3 HCFCs, for 274 compounds, including all isomers and stable conformers Life;me, ODP, GWP, GTP This paper will be submi`ed to a peer-reviewed journal this summer. Life@mes GWPs HCFC-141b C 2 H 3 Cl 2 F HCFC-235fa CClF 2 CH 2 CF 3 C 2 C 1 C 3 Papanastasiou, et al. [2017], NOAA Increasing H

11 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 1 st draft is being written. The completed report will be available in Dec 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

12 Thank you for your attention