Scientific Assessment Panel. Report

1.

Scientific Assessment Panel
Report
COP12(II)/MOP33
29 October 2021
Bonfils Safari (Rwanda), Paul A. Newman (USA)
John A. Pyle (UK), David W. Fahey (USA)
• Status of Scientific Assessment of Ozone
Depletion: 2022
• CFC-11 update
• Antarctic Ozone Hole 2021

2.

Scientific Assessment of
Ozone Depletion: 2022
Steering committee: Julie Arblaster (Australia), Lucy Carpenter (UK),
David Fahey (USA), Jianxin Hu (China), Ken Jucks (USA), Paul
Newman (USA), David Plummer (Canada), John Pyle (UK), Bonfils
Safari (Rwanda) with Sarah Doherty (USA, Report Coordinator)

3.

The Parties’ Request Decision XXXI/2: Potential areas
of focus for the 2022 quadrennial reports of the
Scientific Assessment Panel, the Environmental
Effects Assessment Panel and the Technology and
Economic Assessment Panel
5. That the 2022 report of the Scientific Assessment Panel should include:
a) An assessment of the state of the ozone layer and its future evolution;
b) An evaluation of global and polar stratospheric ozone, including the Antarctic ozone hole and
Arctic winter/spring ozone depletion and the predicted changes…;
c) An evaluation of trends in the top-down derived emissions, abundances and fate in the
atmosphere of trace gases of relevance to the Montreal Protocol on Substances that Deplete the
Ozone Layer, …….;
d) An evaluation of consistency with reported production and consumption of those substances
and the likely implications for the state of the ozone layer, including its interaction with the climate
system;
e) ..the interaction between changes in stratospheric ozone and the climate system, including
possible future policy scenarios …..;
f) Early identification and quantification, where possible, of any other issues of importance to the
ozone layer ……;
g) An assessment of information and research related to solar radiation management and its
potential effect on the stratospheric ozone layer;
h) Relevant information on any newly detected substances that are relevant for the Montreal
Protocol.

4.

2022 Assessment Chapters
Review Editors
1. Ozone-depleting substances
Andreas Engel (Germany)
Johannes Laube (Germany)
Bo Yao (China)
Susann Tegtmeier (Canada)
2. Hydrofluorocarbons (HFCs)
Steve Montzka (USA)
Qing Liang (USA)
Martin Vollmer (Switzerland)
Matt Rigby (UK)
3. Global stratospheric ozone: Past, present & future
Jessica Neu (USA)
Birgit Hassler (Germany)
Wolfgang Steinbrecht (Germany)
Paul Young (UK)
4. Polar stratospheric ozone: Past, present & future
Susan Solomon (USA)
Martyn Chipperfield (UK)
Mark Weber (Germany)
Michelle Santee (USA)
5. Stratospheric ozone changes and climate
Amy Butler (USA)
Harry Hendon (Australia)
Hella Garney (Germany)
Amanda Maycock (UK)
6. Stratospheric aerosol intervention and its potential effect on the stratospheric
ozone layer
Jim Haywood (UK)
Valentina Aquila (USA)
Simone Tilmes (USA)
Karen Rosenlof (USA)
7. Scenarios and information for policymakers
Lambert Kuijpers (Netherlands)
John Daniel (USA)
Don Wuebbles (USA)
Stefan Reimann (Switzerland)
+ Authors
and
Contributors

5.

2020
2022 Assessment Timeline
✓ Discussion Paper circulated for comments by scientific community
✓ Lead Authors and Chapter Editors established
✓ Meetings of SSC & Lead Author teams (Feb.)
2021
✓ Extended outlines of Chapters due (Apr. 16)
✓ SSC/LAs/REs review extended outlines (Apr. 19-30)
✓ Preliminary 1st order drafts (FODs) of Chapters due (Aug. 6)
✓ Internal review/edits of prelim. FODs (Aug. 6-31)
✓ 1st order drafts (FODs) of Chapters due (Sept. 30)
External Review of FODs (Oct. 4-Nov. 12)
2022
2nd order drafts (SODs) of Chapters due (Jan. 28)
Draft of Exec. Summary messages due (March 11)
Mtg. to review Chapters, key messages (March 21-25)
3rd order drafts (TODs) of Chapters due (May 13)
Cited papers accepted for publication (May 31, 2022)
Panel Review Meeting for Exec. Summary (Les Diablerets, Jul. 25-29)

6.

The 2021 ozone hole is the 13th
largest of 33 from 1988
2021
late-1990s to early-2000s period
2021
24.3 M km2
Ozone hole area
(million km2)
2006
Other ozone hole metrics
show similar behavior

7.

Area of 2021 ozone hole was consistent with
lower than average Antarctic temperatures
and the decline in atmospheric chlorine and
bromine
colder than
average
Ozone hole area
(million km2)
warmer than
average
Stratospheric
chlorine and
bromine amount
(EESC)

8.

• The 2021 ozone hole is smaller in area than the average ozone
holes observed in the late-1990s to early-2000s period.
• Without a Montreal Protocol, the 2021 ozone hole is projected
to have been larger, at around 26-27 M km2.
• The current stratospheric meteorology suggests a later than
average ozone hole break-up in the November to December
period.

9.

Report on
unexpected CFC-11
emissions was
published earlier this
year and discussed
at OEWG 43
https://ozone.unep.org.science/assessment/sap

10.

Presentation given at the 2021
Quadrennial Ozone Symposium by
Montzka et al.
CFC-11 ambient concentration
at remote sites
242
240
238
Eight
NH sites
NOAA data only
Updated CFC-11
measurements indicate:
that the accelerated
atmospheric concentration
decline observed after 2018
continued through 2020 and
into the first part of 2021.
CFC-11 (ppt)
236
234
232
*
Four
SH sites
230
*
228
226
224
222
220
2010
Global
production
banned in 2010
2012
2014
Projected
declines
2016
2018
2020
2022
year
* Montzka et al., 2018 (https://doi.org/10.1038/s41586-018-0106-2)
* Montzka et al., 2021 (https://doi.org/10.1038/s41586-021-03260-5)

11.

With the updated concentration
data, global emissions for 2020
can now be derived.
global emission (Gg yr-1)
100
NOAA data
90
80
2018
70
60
2019
50
40
Emission, const. dynamics
Emission with bias corrections (TOMCAT)
2020
2020 global CFC-11 emissions
30
1995 2000 2005 2010 2015 2020
- are even lower than those in 2019
year
- are substantially below 2008-2012 - Red lines and points are best estimates that account for
changing atmospheric dynamics in the derived emission
magnitudes.
estimate. These bias corrections are similarly derived by
two 3-D models
- Errors represent network uncertainties, but do not include
lifetime uncertainties. Uncertainties on the updated results
are not shown as they await updated data from the AGAGE
network

12.

Global atmospheric mole fractions of CFC-11:
• continued to drop rapidly through 2020 and the first
part of 2021.
2020 global CFC-11 emissions:
• Are even lower than those in 2019
• Are substantially below 2008-2012 values
• Are approaching expected levels, suggesting that
much of the new use and unreported production may
have stopped
Important questions remain concerning banks, other
species, etc. See Assessment!

13.

14.

Are emissions back on track?
Hard question to answer because the
expected emission drop from old
banks is uncertain.
TEAP estimates emissions in 2020
from the new bank to be ~6 Gg yr-1.
100
Emission,
Emission,const.
const.dynamics
dynamics
Emission
Emissionwith
withbias
biascorrections
corrections(TOMCAT)
(TOMCAT)
90
global emission (Gg yr-1)
The emission drop indicates the
successful mitigation of much of
the unexpected emission.
80
70
Lickley et al.,
2020
2018
60
2019
50
40
2020
30
+6
20
10
2000
TEAP expectation (bank
emission from old production)
2005
2010
year
2015
2020
Take home message #3:
2020 emissions are approaching expected levels, suggesting much of
the new use and production may have stopped. Although emissions
will remain enhanced from the newly created bank for some time.