Report of the Scientific Assessment Panel SAP Co-chairs Ayité-Lô Ajavon (Togo) Paul Newman (USA) John Pyle (UK) A.R. Ravishankara (USA) Coordinator/Editor.

Report of the Scientific Assessment Panel

SAP Co-chairsAyité-Lô Ajavon (Togo)

Paul Newman (USA)John Pyle (UK)

A.R. Ravishankara (USA)

Coordinator/EditorChris Ennis (USA)

Special thanks to:Malcolm Ko

Ted ShepherdSusan Solomon

with reviews and Executive Summary

We are indebted to the two previous co-chairs:Daniel Albritton and Robert Watson

22nd Meeting of the Parties to theUnited Nations Montreal Protocol

November 8-12Bangkok, Thailand

Seventh Scientific Assessment since MP

Scientific Assessment ofOzone Depletion: 2010

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Terms of reference- The Montreal Protocol Parties’ interests:a) Assess the state of the ozone layer (including the ozone hole) and UV

changes, and their future evolution (the best information at this date)

b) Evaluate trends of ozone-depleting substances in the atmosphere

c) Assess the impacts of climate change on ozone layer

d) Assess the impacts of ozone layer changes on climate

e) Assess approaches to evaluating very short-lived substances (likely substitutes for CFCs, transition chemicals, and new uses)

f) Assess up-to-date information on HFCs and Carbon Tet (in a UNEP request)

Executive Summary

Prologue: A Historic Perspective and Recap of 2006 Assessment

Chapter 1: Ozone-Depleting Substances (ODSs) and Related Chemicals Steve Montzka (NOAA, USA); Stefan Reimann (EMPA, Switzerland)

Chapter 2: Stratospheric Ozone and Surface Ultraviolet RadiationAnne Douglass (NASA, USA) ; Vitali Fioletov (Environment Canada, Canada)

Chapter 3: Future Ozone and Its Impact on Surface UVSlimane Bekki (CNRS, France); Greg Bodeker (Bodeker Scientific, New Zealand)

Chapter 4: Stratospheric Changes and ClimatePiers Forster (University of Leeds, UK); Dave Thompson (Colorado State University, USA)

Chapter 5: A Focus on Information and Options for PolicymakersJohn Daniel (NOAA, USA); Guus Velders (Netherlands Environmental Assessment Agency,

Netherlands)

Twenty Questions and Answers About the Ozone Layer: 2010 UpdateDavid W. Fahey (NOAA, USA); Michaela Hegglin (University of Toronto, Canada)

Assessment Report Contents

To aid decision makers, students, new users… More “user friendly”

Seventh Assessment: Details

Major Milestones:Executive Summary released September 16, 2010Report to the Parties November 11, 2010

Posting on the websites:WMO: http://www.wmo.int/pages/mediacentre/press_releases/documents/

898_ExecutiveSummary.pdfUNEP: http://ozone.unep.org/highlights.shtml

Full report available to Parties in January 2011; printed April 2011

Participants: Over 300 scientists from 34 countries

Roles: Cochairs; Coordinating Lead Authors; Lead Authors;Coauthors, Contributors, Reviewers

First-draftpreparation &

review

Second-draftpreparation &

review

Final chapter preparation & document editing

Third-draft preparation &

review

2009 2010 2011

We are here

Report of the Scientific Assessment Panel

2006

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Montreal Protocol is working!

2010

ODSs

Climate Change

Ozone hole

Global ozone

Global UV Change

Strengthened: Montreal Protocol is working!

Ozone-Depleting Substances (ODSs)

The abundances of ODSs in the atmosphere are responding as expected to the controls of the Montreal Protocol.

Total chlorine from ODSs continues to decline in both the lower atmosphere and the stratosphere.

CFCs (not methyl chloroform) now contributing most to the chlorine decline. Carbon tetrachloride (in troposphere) is declining more slowly than expected and

the exact cause is not certain. (Can provide more information at the end.) Total bromine from ODSs is declining in the lower atmosphere and is no longer

increasing in the stratosphere. For the first time, the global atmospheric abundance of bromine from halons

stopped increasing, and halon-1211 actually declined. Abundances of most HFCs and HCFCs are growing in the atmosphere. Some

HCFCs (e.g., HCFC-22, HCFC-142b) increased faster than expected during the past four years.

Increasing abundances of radiatively important gases, especially carbon dioxide(CO2) and methane (CH4), are expected to significantly affect future stratospheric ozone through effects on temperature, winds, and chemistry.

For the next few decades, the decline in ODSs will dominate the recovery of the ozone layer.

As ODSs decline, climate change and other factors are expected to become increasingly more important to the future ozone layer.

Ozone levels globally and at midlatitudes may even become larger than those before 1980.

The Ozone Layer and Climate Change

The ozone layer and climate change are intricately coupled, and climate change will become increasingly more important to the future ozone layer.

The ozone hole that occurs in austral springtime is projected to recover later in the century than any other region of the globe.

The Antarctic ozone hole is much less influenced by climate change than other areas of the globe.

ODSs primarily determine when the ozone hole will heal.

Antarctic Ozone Hole

Control of ODSs by the Montreal Protocol has protected the ozone layer from much higher levels of depletion.

Globally, the ozone layer is projected to recover to its 1980 level before the middle of this century.

The Global Ozone Layer

Global surface UV levels have not increased significantly because the global ozone loss has been limited.

If there were no MP, the surface UV levels would have been large

Factors other than stratospheric ozone will determine surface UV levels in the future.

Surface Ultraviolet Radiation

The ozone layer and surface ultraviolet (UV) radiation are responding as expected to the ODS reductions achieved under the Montreal Protocol.

Control of ODSs by the Montreal Protocol also has had co-benefits for climate.

The decrease in ODSs achieved under the Montreal Protocol is equivalent to a reduction of carbon dioxide (CO2) that is five times larger than the target of the first commitment period of the Kyoto Protocol.

Projections of HFC growth scenarios that assume no controls suggests that by 2050, GWP-weighted emissions of HFCs can be comparable to GWP-weighted emissions of CFCs at their peak in 1988.

Montreal Protocol and Climate

Other Information for You

The accelerated HCFC phase-out agreed to in 2007 is projected to reduce ozone depletion and to help reduce climate forcing.

New fluorocarbons, suggested as possible replacements for HCFC and HFC that are potent greenhouse gases, are less potent greenhouse gases.

Nitrous oxide (N2O) is known to both deplete global ozone and warm the climate. The current ODP-weighted anthropogenic emission is larger than that of any ODS.

Geo-engineering: Deliberate large injections of sulfur-containing compounds into the stratosphere would alter the radiative, dynamical, and chemical state of the stratosphere and could be expected to have substantial unintended effects on stratospheric ozone levels.

Ozone Hole and Surface Climate

The impact of ozone hole on surface climate has become more evident. There are many influences on climate from the ozone hole.

The Antarctic ozone hole has caused wind pattern changes in the Southern Hemisphere lower atmosphere.

Because of these changes, for example, the surface climate has warmed over the Antarctic Peninsula and cooled over the high plateau.

Options for further limiting future emissions of ODSs could advance recovery dates by a few years;

However, the impact these potential emission reductions on future ozone levels would be less than what has already been accomplished by the Montreal Protocol.

Options and Expected Gains

Thank you for

your attention

Backup Slides

16

Emission tonnage of CFCs, HCFCs, and HFCs

1950 1970 1990 2010 2030 2050

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Emissions derived from data reported to UNEP are highly variable and on average appear smaller than those inferred from observed trends. Although the size of this discrepancy is sensitive to uncertainties in our knowledge of how long CCl4 persists in the atmosphere (i.e., lifetime), the variability cannot be explained by lifetime uncertainties. Errors in reporting, errors in analysis of reported data, and/or unknown sources are likely responsible for the year-to-year discrepancies.

Carbon Tetrachloride

Options and Expected Gains