The 2018 WMO/UNEP Scientific Assessment of Ozone Depletion

Transcription

1 The 2018 WMO/UNEP Scientific Assessment of Ozone Depletion 2018 WMO/UNEP Assessment Co-chairs: David Fahey (USA) Paul Newman (USA) John Pyle (UK) Bonfils Safari (Rwanda) Scienti'ic Assessment of Ozone Depletion: 2018 Color? Assessment Coordinator: 2014 Assessment Sarah Doherty (USA) 2018 Assessment

2 Steering Committee Martyn Chipperfield (UK) David Fahey (USA) David Karoly (Australia) Doug Kinnison (USA) Malcolm Ko (USA) Paul Newman (USA) John Pyle (UK) Bonfils Safari (Rwanda) Michelle Santee (USA)

3 Chapters and Lead Authors Chapter 1: Ozone-depleting substances Andreas Engel (Goethe Universität Frankfurt, Germany) Matt Rigby (University of Bristol, UK) Chapter 2: Hydrofluorocarbons Steve Montzka (NOAA, ESRL, USA) Guus Velders (Natl. Inst. for Pub. Health and the Env., Netherlands) Chapter 3: Global stratospheric ozone: Past, present & future Peter Braesicke (Karlsruhe Institute für Technologie, Germany) Jessica Neu (NASA JPL, USA) Chapter 4: Polar stratospheric ozone: Past, present & future Ulrike Langematz (Freie Universität Berlin, Germany) Matt Tully (Bureau of Meterology, Australia) Chapter 5: Stratospheric ozone changes and climate Alexey Karpechko (Finnish Meteorological Institute (Finland) Amanda Maycock (University of Leeds, UK) Chapter 6: Scenarios and information for policymakers Lucy Carpenter (University of York, UK) John Daniel (NOAA, ESRL, USA)

4 International assessment process Assessment report team: 41 Lead authors and co-authors 12 Review Editors 19 Different countries Peer review process: 126 Science reviewers 32 Different countries > 5000 Review comments on first draft!

5 20 Questions and Answers Twenty Questions and Answers About the Ozone Layer: 2014 Update Scientific Assessment of Ozone Depletion: 2014 The 20 Questions document is being revised and updated World Meteorological Organization United Nations Environment Programme National Oceanic and Atmospheric Administration National Aeronautics and Space Administration European Commission

6 Assessment highlights: Comprehensive evaluation of metrics A new table with updated evaluation of abundances, lifetimes, ODPs, GWPs and GTPs of more than 500 compounds. CFCs, HCFCs, HFCs, HCs, halogenated ethers, alcohols and ketones, fluoroesters, etc. Metrics for many HCFCs evaluated for the first time (Papanastasiou et al., 2017) providing new information for Group I Annex C table.

7 Annex C of the Kigali Amendment includes a table of HCFCs with many missing global warming potential (GWP) values. GWPs needed to establish baselines for HFC phase down schedules. A new theoretical NOAA study provides estimates of missing GWPs, otherwise assumed zero. Table includes 274 HCFC isomers Large range of values - structure dependent Detailed laboratory studies could provide more accurate determinations for selected compounds

8 Assessment highlight: Halogenated Very Short Lived Substances (VSLS) Previous assessments have discussed natural and anthropogenic VSLS - ODS with lifetimes less than about 6 months. Recent interest focuses on chlorinated VSLS, including: CH 2 Cl 2 (dichloromethane, DCM), lifetime ~ 140 days CH 2 ClCH 2 Cl (1,2-dichloroethane, DCE), ~ 65 days We estimate VSLS up to ~ 3.3% of lower stratospheric chlorine, with up to ~1.8% from DCM and ~ 0.6% from DCE. Estimates have high uncertainty because of sparse stratospheric observations and variability in VSLS sources.

9 VSLS, continued Tropospheric VSLS chlorine concentrations increased from ~85ppt in 2008 to ~110ppt in Largest increases have occurred for CH 2 Cl 2 (dichloromethane) VSLS chlorine currently makes a very small contribution to stratospheric ozone depletion Understanding the role of VSLS emissions in long-term future stratospheric ozone change remains an open science question.

10 Assessment highlight: Ozone Recovery Arctic ozone remains below average with expected large depletions occurring every few years (e.g., 2011) 2017 Antarctic ozone is well below average with some hints at improvement Small 2017 Antarctic hole mainly due to unusual meteorological conditions

11 Assessment highlight: HFCs Kigali amendment Kigali amendment controls HFC emissions and is projected to limit future surface warming from HFCs to less than 0.1C in 2100 Emissions (GtCO 2 -eq yr -1 ) HFC Emissions GWP-weighted (100-yr) Baseline Velders (2015) Kigali Amendment New chapter on HFCs in the 2018 assessment

12 2018 Assessment Timeline þ Discussion Paper circulated for comments by scientific community þ Lead Authors and Chapter Editors established þ Chapter author teams assembled, early preparation steps begin þ Draft of Chapter outlines (31 Mar) þ 1 st meeting of Lead Authors, Co-chairs, SSC (4-5 May) þ Individual Chapter team meeting (May-Jul) þ Draft chapter summary bullets submitted for review after chapter-level meetings (~15 Jul) þ 1 st drafts of Chapters completed (15 Sep) 1 st drafts sent to reviewers & Review Editors SSC begins writing of Exec. Summary þ Chapter 1 st draft reviews due (15 Nov) þ Collated chapter reviews sent to Lead Authors & Review Editors (by 22 Nov) Review Editors provide feedback to Lead Authors on key items from reviews (~1 Dec) q Prelim. 2 nd draft of Chapters + review responses sent to Rev. Editors (31 Jan) q 2 nd draft of Chapters completed (28 Feb) q Review meeting of 2 nd draft (Boulder, CO, March) Presentation of Exec. Summ. 1 st draft, based on Chapter 2 nd drafts SSC meets to revise Exec. Summ. the day after the meeting concludes q All cited papers accepted for publication (15 May) q Final versions of Chapters completed (1 June) q Panel Review Meeting for Exec. Summary (Les Diablerets, Jul)

13 Thank you for your attention

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