Report of the Scientific Assessment Panel24th Meeting of the Parties to theUnited Nations Montreal Protocol

12-16 November 2012Geneva, Switzerland

Cochairs:Ayité-Lo Ajavon (Togo)Paul A. Newman (USA)

John A. Pyle (UK)A.R. Ravishankara (USA)

Today’s Summary: status of the 2014 report of the Scientific Assessment Panel summary on carbon tetrachloride issues summary on new compound R316c

The 2014 Science Assessment

November 2011: Parties define terms of reference (23rd MOP [Bali], Decision XXIII/13)

Fall 2012: Preparatory work begins

October meeting of SAP Cochairs in Paris

Communication from SAP Cochairs and UNEP to the Parties, seeking nominations of participants

Replies requested by December 19

Previous participants need not be renominated; they will be considered again

Replies to be sent to UNEPcontact: Meg.Seki@unep.org

The 2014 Science Assessment

Science topics to be addressed (Decision XXIII/13):• assess the state of the ozone layer and its future evolution (including, e.g.,

effects of sudden stratospheric warmings, or Brewer-Dobson circulation changes)

• evaluate recent Antarctic ozone hole and Arctic ozone depletion behavior and predicted changes (especially focus on temperatures of the polar stratosphere)

• evaluate trends of ozone-depleting substances in the atmosphere and their consistency with reported production and consumption

• assess the interaction between the ozone layer and the atmosphere (esp. polar ozone depletion/tropospheric climate, ocean/atmosphere coupling)

• describe ozone and surface ultraviolet radiation observations, and future expectations

• further assessment of effects of ODSs and ozone-relevant substances, if any

• identification of any other threats to the ozone layer

The 2014 Science Assessment

Our Coming Steps:Parties to nominate experts to be authors or reviewers (by December 19, 2012)Co-chairs solicit comments from scientific community on draft Chapter structure, author suggestionsFinalize Chapter structure, Chapter LeadsChapter Teams form, Chapter preparation beginsLead Author meeting to discuss Chapter outlinesLead Author meeting to review Chapter first draftsMail review, in-person review (Le Diableret, CH), final Exec. summary in 2014Publication of assessment report in 2015

Nov-Dec ’12Parties’

Nominationof Experts

Dec ’12/Jan ’13Determine Chapter Structure and Leads

Feb-Oct ’13Form Chapter Teams

Prepare ChapterFirst Draft

Nov/Dec ’13Lead Author Meeting,

First Draft Review

20132012

Summary of new information on carbon tetrachloride (CCl4)

• A revision of the lifetime will reduce the “top-down” emission estimate by approximately 10-20 Gg/yr.

• Estimates of global emissions from contaminated sites and landfills are approximately 8-12 Gg/yr, revising upward the “bottom-up” emission estimate.

• The 40 Gg/yr emission budget gap between the “top-down” and “bottom-up” estimates has been narrowed, but not quite closed.

• The simple assumptions made in WMO/UNEP (2011) to estimate fugitive emissions suggest that those emissions alone cannot explain the 40 Gg/yr budget gap.

Summary of information on chlorofluorocarbon: R-316c

(C4F6Cl2)

• Mainly photolyzed in the stratosphere by solar UV radiation

• Lifetime of 81 years• A potent ODS with an ODP of

approximately 0.5• A powerful greenhouse gas with a 100-

y GWP of 4300

SAP report summary

• Preparatory work for the “Scientific Assessment of Ozone Depletion: 2014” has begun. The SAP co-chairs request that the Parties nominate expert participants.

• The carbon tetrachloride emissions budget gap has been narrowed, but not quite closed.

• The RC-316c is both a powerful ODS and greenhouse gas