# Presentation: 577745

## 2006 WMO/UNEP Scientific Assessment of Ozone Depletion and CCSP Product 2.4: Ozone-Depleting Substances

**A. Ravishankara**, NOAA

_*Two separate parts to the talk*_*:*
- The WMO/UNEP ozone assessment.
- The Development of CCSP Product 2.4 based on 			available International assessments.

- CCSP

## What are the major issues?

- 1. _Stratospheric ozone is a UV-shield_:
- •	 Its depletion will increase surface UV, with 		 consequences to health and composition of 		 troposphere.
-  This is not a theory to be tested - it is reality!
-  O3 hole, trends in O3 abundance, etc.: 					need predictions.
- 2. _Stratospheric ozone is an important “climate gas”:_
-    •	Its changes influence earth’s climate 			(circulation, temperatures and composition.)
- 3. _Ozone-depleting substances and the substitutes for __	__	__ODSs (even non-ozone-depleting ones) are __	__	__also “climate gases”:_
- 	– What is the net influence of changing 								stratospheric O3 and CFCs simultaneously?
- 	– What are the impacts of substitutes, CFCs, etc.?

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## Major issues, continued

_**Major issues, continued**_

- 4.	_Accountability phase of Montreal Protocol_:
-     	Now that we have phased out CFCs,
- 		–	 	Are CFCs decreasing in the lower atmosphere?
- 		–	  Are Halogens decreasing in the Stratosphere?
- 		–		Are the ozone-depleting components 								decreasing in the stratosphere?
- 		–		Is stratospheric ozone recovering?
- 					When will it be back to “normal”?
- 5.	_Climate is changing as we look for ∆O__3_:
- 		What is the influence of climate and its changes on ozone changes?
- 			–		How will this help/hinder the “recovery” of global 							stratospheric O3?
- 			–		How will this help/hinder the “recovery” of polar 							ozone depletion?
- 6.	_What are the influences of other compositional changes on stratospheric O__3_? 		e.g., ∆CH4, ∆N2O, ...
- 7. _Are our methods for developing good substitutes working well_?
- 		e.g., are the very short-lived compounds OK?

_***Stratospheric ∆O***__***3***__*** is a a key part of global climate change***_*** –***_*** ***_
_***both influence and impact.***_

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## WMO/UNEP 2006 Ozone Assessment

- _There have been many previous assessments_:
- 		•  Each builds on the previous one – 8 assessments since 1981.
- _Reference what’s new since the 2002 assessment_:
- •	The “this is an update” message from the previous assessments.
- _Chapter structure and length_:
- 		•	Easy-to-find information.
- 		•	Shorter than the previous assessment.
- _The Montreal Protocol Parties’ interests for the 2006 assessment_:
- 		•	Observed trends in ODS and their consistency with reported production;
- 		•	Ozone-depleting impacts of new (e.g., short-lived) halogen-containing substances;
- 		•	Methyl bromide sources and sinks & implications for the ozone layer;
- 		•	Relations between ozone depletion and climate change, including feedbacks;
- 		•	Changes in global and polar ozone and ultraviolet radiation;
- 		•	Future projections and scenarios for ozone & UV (climate impact?)

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## A Little Context:The International Assessment Process

- •	_What the assessments are_:
- 		>	_State of science_:  What we know & what we don’t, framed in _policy-useful terms_.
- 		>	_Scientific documents_, prepared & reviewed by the expert communities (scientists).
- 		>	_Assessed_ viewpoints, not _reviews_.
- 		>	“_One-stop_ shopping”:		>	Science of the ozone layer
- 									>	Impacts of ozone change
- 									>	Technology/economics of options
- 		>	Well-identified “_customers_”:	    	>	Governments, via the Montreal Protocol
- 												 >	Industry
- 												 >	Public
- 												 >	Scientific community
- •	_What the assessments are not_:
- 		>	They don’t make _policy_ recommendations.
- 		>	They are not _research-planning_ documents, nor do they “_push_” research
- 				projects or needs.
- 				(They _do_ identify gaps in information that may limit informed decision-making.)
- 		>	No one assessment report is the “_final word_”.
- 				(Both policy and research are endeavors that interact over the years.)

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## Description: WMO/UNEP Assessment of Stratospheric Ozone Depletion 2006 

_*	*__*Section I*_
- 		Chapter 1:  Long-Lived Compounds *(Cathy Clerbaux and Derek Cunnold)*
- 		Chapter 2:  Very Short-Lived Halogenated Compounds *(Kathy Law and Bill Sturges)*
_*	*__*Section II*_
- 		Chapter 3:  Global Ozone: Past and Present *(Martyn Chipperfield and Vitali Fioletov)*
- 		Chapter 4:  Polar Ozone: Past and Present *(Paul Newman and Markus Rex)*
_*	*__*Section III*_
- 		Chapter 5:  Climate-Ozone Connections *(Mark Baldwin and Martin Dameris)*
- 		Chapter 6:  The Ozone Layer in the 21st Century *(Greg Bodeker and Darryn Waugh)*
- 		Chapter 7:  Surface UV Radiation: Past, Present, and Future *(Alkis Bais and Daniel Lubin)*
- 		Chapter 8:  Projections and Impacts *(John Daniel and Guus Velders)*

_**Cochairs**_
- Ayité-Lô Ajavon (Togo);
- Daniel L. Albritton (USA)
- Robert T. Watson (USA)
_**Steering Committee**_
- Marie-Lise Chanin (France);
- Susana Diaz (Argentina);
- John Pyle (UK);
- A. R. Ravishankara (USA);
- Theodore Shepherd (Canada)

_**Description: **__**WMO/UNEP**__** Assessment of Stratospheric Ozone Depletion 2006**_

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**Notes:**
The 4 bullets are the key.
The bottom part shows how the SPARC reports and reviews map on to the Assessment chapters.

## Some of the key “new” emphasesfor the 2006 assessment

_**Multiple issues impact  future ozone**_:
- >	Ozone Depleting Substances –
- 		Montreal Protocol... Implications... Future Decisions?
- >	_Climate Change_ –
- 		natural and anthropogenic... GHGs... temperature, transport, H2O,...
- >	Other compositional changes –
- 		(due to climate change or other reasons)

** ****Influence of climate change on stratospheric changes to ****	****	****date and in the future.**
-  Influence of changes in the stratospheric ozone on 			climate – in the past and future.

**A longstanding issue...**
**	****Previous assessments.**

**Stand-alone ****	****	****chapter(s) on**
**	****this issue.**

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## Some of the key questions for this assessment

**  ****What is the interplay between changes in ODS and ****	****	****	****changes in climate?**
**  ****How does the changing composition and changing ****	****	****	****climate influence the stratospheric ozone levels in ****	****	****	****the future?**

_**Some of the key questions for this assessment**_

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## Overall Timetable & Major Milestones

_**January-April 2005**_**:  Draft assessment outline completed; **
**Lead Authors, Coauthors established; chapter planning and**
**writing commences.****	****	**
_**November 2005**_**: ****Chapter First Drafts**** completed and First Review Meeting held**
_**February-March 2006**_**: ****Chapter Second Drafts**** completed and peer-reviewed by mail**
_**May-June 2006**_**: ****Chapter Third Drafts**** completed and ****Panel Review Meeting**** held (19-23 June, Les Diablerets, Switzerland)**
** ****> Final decisions on chapters   > Completed Executive Summary**
_**30 December 2006**_**: Preprint volume to UNEP for government distribution.**
_**March 2007**_**: Final printed copies available.**

**2005**

**2006**

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**We **
**are **
**here**

## The Context for CCSP Product 2.4

- 	>	∆ UV
- 	>	∆ Climate
- 	>	∆ Tropospheric composition
_**International assessments provide one “scientifically vetted”, universally-accepted**_**, ****	****	****	**_**way to assess the state-of-understanding in this area.**_
- _	_>  There are (will be) multiple recent assessments available to draw upon:
- 		-	IPCC/TEAP “Special Report on Ozone and Climate  (SROC; 2005)
- 		-	WMO/UNEP O3 Assessment  (final copies in early 2007)
- 		-	IPCC Fourth Assessment Report (2007)
- _	__These are the assessments to which we have contributed science and assessment efforts_!
**Use the findings from assessments to figure out what is implied: S&AP  2.4**

_**The Context for CCSP Product 2.4**_

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## IPCC (2005)

- Joint IPCC WG1/WG3/TEAP Special Report published in 2005.
- Provides information on some key issues:
- >  Banking
- >  Combined effects of 	ODS and their O3.

- Thanks to Susan Solomon for the information and slides.

## Examples of some key findings from SROC

-  Direct radiative forcing

- Radiative Forcing

- (

- W m

- -2

- )

- Methyl chloroform

- HFCs

- PFCs

- Methyl bromide

- Halons

- Carbon tetrachloride

- HCFCs

- CFCs

-  Indirect radiative forcing

- >  Positive direct forcing due to ODSs only:
- 	0.32 ± 0.03 W/m2.
- >  Negative indirect forcing due to ozone depletion:
- 	-0.15 ± 0.10 W/m2.

**•**  _Different types of gases make_ _different contributions to_ _positive and negative_ _forcing_.

**•**  _Banking of ODSs is a major issue_.
**•**  _What are its manifestations and consequences_?

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## A few key findings from SROC report, continued

- ~7.5 Gt near 1990, about 33% of that year's CO2 emissions from global fossil fuel burning.
- ~2.5 Gt near 2000, about 10% of that year’s CO2 emissions from global fossil fuel burning.

- Combined CO2-equivalent emissions from halocarbons:

- •  _Cooling due to ozone depletion and warming due_ _to greenhouse effects of ODSs may not occur in_ _the same places and times_.

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- •  _The fraction of “CO__2__-equivalent emissions_”
-       _from ODSs is decreasing._

## What the WMO/UNEP 2006 report will provide

-   An assessment of the ODSs in the current and future 					stratosphere.
-   The expected levels of stratospheric ozone in the 21st century
-   An assessment of the impact of changes in climate on the future 			of the ozone layer.
-   An evaluation of the substitutes for ozone depleting gases and 				their impact on the radiative forcing of the atmosphere.
-   The efficacy of using short-lived substitutes for ODSs.

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## IPCC 2007 Climate Change Assessment

-   A broad report that addresses the science of climate change.
-   The assessment will place the stratospheric ozone changes in 			the broad context of climate change.
-   Expected to be available in 2007.

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## CCSP S&A Product 2.4: Stratospheric ozone – A plan

-  Prospectus: scope and details of the product- under development.
-  Assemble a collection of Federal Scientists to “crystallize” the 			findings of the 3 International reports (SROC, WMO/UNEP 			2006, and IPCC 2007) in policy-relevant terms and in the 			context of U.S. needs.
-  Write report  (mid-2007).
-  Review as a CCSP product (end of 2007).
-  Publish as a CCSP product (early 2008).

***A good example of how we can take advantage of the international assessments (for which we contribute science and assessment time!) for our needs.***

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